Health in the Anthropocene Epoch—implications for epidemiology Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-16 Haines A.
Humanity has entered a new geological epoch during which dramatic environmental trends, on a range of scales from local to global, are transforming natural systems. The predominant influence of Homo sapiens on the global environment has led to the growing use of the term ‘Anthropocene Epoch’1 to distinguish it from the ‘Holocene Epoch’, a climatically generally benign period which lasted around 11 500 years, during which humanity developed from hunter-gatherer and agrarian societies to increasingly urbanized communities. This transformation has been accompanied by pronounced increases in energy and freshwater use to drive economic growth and satisfy the growing demands of humanity for food and natural resources.2,3 It has resulted in unprecedented human progress, including the ‘Escape from Poverty’4 of many millions of people, particularly in Asia and Latin America. Since 1900, the global average life expectancy has more than doubled and is now almost 70 years. All countries in the world have a higher life expectancy than the countries with the highest life expectancy in 1800.5
The history in epidemiology Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-16 Anderson W.
In thinking of the history of epidemiology, the map usually comes to mind before the calendar or the clock. During the nineteenth century, the study of the pattern and distribution of disease commonly suggested a terrain, a spatial ordering, that might align with environmental hazards, or later, with bacteriological threats. One thinks, for example, of John Snow’s mapping of the prevalence of cholera in London, which now seems static, fixed at a certain point in time.1 Of course, epidemiology always has been predicated on assumptions about change over time, or temporality—as the conventional triangulation of time, place and person indicates. And yet, whereas we talk freely of the ‘eras’ of epidemiology, conferring on the field a kind of historicity, rarely have we considered carefully and critically the various temporalities implicit in different styles of epidemiological investigation, the canon of chronological technique.2 The question here, then, is not what is the history of epidemiology, but rather what is the history in epidemiology?
Med4way: a Stata command to investigate mediating and interactive mechanisms using the four-way effect decomposition Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-16 Discacciati A, Bellavia A, Lee J, et al.
The overall effect of an exposure on an outcome, in the presence of a mediator with which the exposure may interact, can be decomposed into four components that correspond to the portion of the effect that is due: (i) to neither mediation nor interaction; (ii) to just interaction (but not mediation); (iii) to both mediation and interaction; and (iv) to just mediation (but not interaction). This four-way decomposition unifies methods to attribute effects to interactions and methods that assess mediation. We introduce the Stata command med4way to estimate the causal contrasts that arise in this decomposition. Med4way is implemented as a Stata stand-alone command requiring Stata version 10 or higher (StataCorp, College Station, TX, USA), and allows estimating the four-way decomposition using parametric regression models. Med4way can be used when the outcome is continuous, dichotomous, count or survival time, and the mediator is continuous or binary. The command accommodates cohort and case-control designs. We present two examples of application of the command to gain insight on important public health problems. In the first application, we employ med4way to investigate the role of birth outcomes in explaining the effect of maternal exposure to manganese on child neurodevelopment. In the second application, we investigate the role of stage at diagnosis in explaining income disparities in colorectal cancer survival. The command is freely available on GitHub [https://github.com/anddis/med4way] and has been published under General Public License (GPL) version 3.
How often can meta-analyses of individual-level data individualize treatment? A meta-epidemiologic study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-15 Schuit E, Li A, Ioannidis J.
BackgroundOne of the claimed main advantages of individual participant data meta-analysis (IPDMA) is that it allows assessment of subgroup effects based on individual-level participant characteristics, and eventually stratified medicine. In this study, we evaluated the conduct and results of subgroup analyses in IPDMA.MethodsWe searched PubMed, EMBASE and the Cochrane Library from inception to 31 December 2014. We included papers if they described an IPDMA based on randomized clinical trials that investigated a therapeutic intervention on human subjects and in which the meta-analysis was preceded by a systematic literature search. We extracted data items related to subgroup analysis and subgroup differences (subgroup–treatment interaction p < 0.05).ResultsOverall, 327 IPDMAs were eligible. A statistically significant subgroup–treatment interaction for the primary outcome was reported in 102 (36.6%) of 279 IPDMAs that reported at least one subgroup analysis. This corresponded to 187 different statistically significant subgroup–treatment interactions: 124 for an individual-level subgrouping variable (in 76 IPDMAs) and 63 for a group-level subgrouping variable (in 36 IPDMAs). Of the 187, only 7 (3.7%; 6 individual and 1 group-level subgrouping variables) had a large difference between strata (standardized effect difference d ≥ 0.8). Among the 124 individual-level statistically significant subgroup differences, the IPDMA authors claimed that 42 (in 21 IPDMAs) should lead to treating the subgroups differently. None of these 42 had d ≥ 0.8.ConclusionsAvailability of individual-level data provides statistically significant interactions for relative treatment effects in about a third of IPDMAs. A modest number of these interactions may offer opportunities for stratified medicine decisions.
Relative contributions of prenatal complications, perinatal characteristics, neonatal morbidities and socio-economic conditions of preterm infants on the occurrence of developmental disorders up to 7 years of age Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-13 Müller J, Hanf M, Flamant C, et al.
Background To investigate the relative contributions of prenatal complications, perinatal characteristics, neonatal morbidities and socio-economic conditions on the occurrence of motor, sensory, cognitive, language and psychological disorders in a large longitudinal preterm infant population during the first 7 years after birth. Methods The study population comprised 4122 infants born at <35 weeks of gestation who were followed for an average of 74.0 months after birth. Developmental disorders, including motor, sensory, cognitive, language and psychological, were assessed at each follow-up visit from 18 months to 7 years of age. The investigated determinants included prenatal complications (prolonged rupture of membranes >24 hours, intrauterine growth restriction, preterm labour and maternal hypertension), perinatal characteristics (gender, multiple pregnancies, gestational age, birth weight, APGAR score and intubation or ventilation in the delivery room), neonatal complications (low weight gain during hospitalization, respiratory assistance, severe neurological anomalies, nosocomial infections) and socio-economic characteristics (socio-economic level, parental separation, urbanicity). Based on hazard ratios determined using a propensity score matching approach, population-attributable fractions (PAF) were calculated for each of the four types of determinants and for each developmental disorder. Results The percentages of motor, sensory, cognitive, language and psychological disorders were 17.0, 13.4, 29.1, 25.9 and 26.1%, respectively. The PAF for the perinatal characteristics were the highest and they were similar for the different developmental disorders considered (around 60%). For the neonatal and socio-economic determinants, the PAF varied according to the disorder, with contributions of up to 17% for motor and 27% for language disorders, respectively. Finally, prenatal complications had the lowest contributions (between 6 and 13%). Conclusions This study illustrates the heterogeneity of risk factors on the risk of developmental disorder in preterm infants. These results suggest the importance of considering both medical and psycho-social follow-ups of preterm infants and their families.
Lipid metabolic networks, Mediterranean diet and cardiovascular disease in the PREDIMED trial Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-13 Wang D, Zheng Y, Toledo E, et al.
Background Perturbed lipid metabolic pathways may play important roles in the development of cardiovascular disease (CVD). However, existing epidemiological studies have focused more on discovering individual lipid metabolites for CVD risk prediction rather than assessing metabolic pathways. Methods This study included a subcohort of 787 participants and all 230 incident CVD cases from the PREDIMED trial. Applying a network-based analytical method, we identified lipid subnetworks and clusters from a global network of 200 lipid metabolites and linked these subnetworks/clusters to CVD risk. Results Lipid metabolites with more double bonds clustered within one subnetwork, whereas lipid metabolites with fewer double bonds clustered within other subnetworks. We identified 10 lipid clusters that were divergently associated with CVD risk. The hazard ratios [HRs, 95% confidence interval (CI)] of CVD per a 1-standard deviation (SD) increment in cluster score were 1.39 (1.17–1.66) for the hydroxylated phosphatidylcholine (HPC) cluster and 1.24 (1.11–1.37) for a cluster that included diglycerides and a monoglyceride with stearic acyl chain. Every 1-SD increase in the score of cluster that included highly unsaturated phospholipids and cholesterol esters was associated with an HR for CVD of 0.81 (95% CI, 0.67–0.98). Despite a suggestion that MedDiet modified the association between a subnetwork that included most lipids with a high degree of unsaturation and CVD, changes in lipid subnetworks/clusters during the first-year follow-up were not significantly different between intervention groups. Conclusions The degree of unsaturation was a major determinant of the architecture of lipid metabolic network. Lipid clusters that strongly predicted CVD risk, such as the HPC cluster, warrant further functional investigations.
Population-level mortality benefits of improved blood pressure control in Indonesia: a modelling study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-13 Sudharsanan N.
Background There are few estimates of the potential gains in adult mortality from population-level improvements in systolic blood pressure (SBP) in a major low-and-middle income country (LMIC). Using nationally representative cohort data from Indonesia—the third most populous LMIC— I estimated the gains in adult life expectancy from improving SBP control among adults ages 40 and above and assessed the benefits among richer and poorer subpopulations. Methods I used longitudinal data from 10 085 adults ages 40 and above (75 288 person-age observations) enrolled in the 2007 and 2014/15 waves of the Indonesian Family Life Survey. Next, I used Poisson-regression parametric g-formulas to directly estimate age-specific mortality rates under different blood pressure control strategies and constructed period life expectancies using the observed and counterfactual mortality rates. Results Fully controlling SBP to a population mean of under 125 mmHg was associated with a life expectancy gain at age 40 of 5.3 years [95% confidence interval (CI): 3.2, 7.4] for men and 6.0 years (95% CI: 3.6, 8.4) for women. The gains associated with blood pressure control were similar for both rich and poor subpopulations. The life expectancy gains under scenarios with imperfect blood pressure control and coverage were more modest in size and ranged between 1 and 2.5 years for a large fraction of the scenarios. Conclusions In Indonesia, elevated SBP carries a large mortality burden, though the results suggest that realistic efforts to address hypertension will likely produce more modest gains in life expectancy. Comparing improvements from different strategies and identifying the most cost-effective ways to introduce and scale up hypertension interventions is a critical focus for both research and policy.
Improving the visualization, interpretation and analysis of two-sample summary data Mendelian randomization via the Radial plot and Radial regression Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-13 Bowden J, Spiller W, Del Greco M F, et al.
First published online: 28 June 2018, Int J Epidemiol, doi: https://doi.org/10.1093/ije/dyy101
Using genetics to understand the causal influence of higher BMI on depression Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-13 Tyrrell J, Mulugeta A, Wood A, et al.
BackgroundDepression is more common in obese than non-obese individuals, especially in women, but the causal relationship between obesity and depression is complex and uncertain. Previous studies have used genetic variants associated with BMI to provide evidence that higher body mass index (BMI) causes depression, but have not tested whether this relationship is driven by the metabolic consequences of BMI nor for differences between men and women.MethodsWe performed a Mendelian randomization study using 48 791 individuals with depression and 291 995 controls in the UK Biobank, to test for causal effects of higher BMI on depression (defined using self-report and Hospital Episode data). We used two genetic instruments, both representing higher BMI, but one with and one without its adverse metabolic consequences, in an attempt to ‘uncouple’ the psychological component of obesity from the metabolic consequences. We further tested causal relationships in men and women separately, and using subsets of BMI variants from known physiological pathways.ResultsHigher BMI was strongly associated with higher odds of depression, especially in women. Mendelian randomization provided evidence that higher BMI partly causes depression. Using a 73-variant BMI genetic risk score, a genetically determined one standard deviation (1 SD) higher BMI (4.9 kg/m2) was associated with higher odds of depression in all individuals [odds ratio (OR): 1.18, 95% confidence interval (CI): 1.09, 1.28, P = 0.00007) and women only (OR: 1.24, 95% CI: 1.11, 1.39, P = 0.0001). Meta-analysis with 45 591 depression cases and 97 647 controls from the Psychiatric Genomics Consortium (PGC) strengthened the statistical confidence of the findings in all individuals. Similar effect size estimates were obtained using different Mendelian randomization methods, although not all reached P< 0.05. Using a metabolically favourable adiposity genetic risk score, and meta-analysing data from the UK biobank and PGC, a genetically determined 1 SD higher BMI (4.9 kg/m2) was associated with higher odds of depression in all individuals (OR: 1.26, 95% CI: 1.06, 1.50], P=0.010), but with weaker statistical confidence.ConclusionsHigher BMI, with and without its adverse metabolic consequences, is likely to have a causal role in determining the likelihood of an individual developing depression.
Intervention effect estimates in cluster randomized versus individually randomized trials: a meta-epidemiological study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-09 Leyrat C, Caille A, Eldridge S, et al.
Background Cluster (CRTs) and individually randomized trials (IRTs) are often pooled together in meta-analyses (MAs) of randomized trials. However, the potential systematic differences in intervention effect estimates between these two trial types has never been investigated. Therefore, we conducted a meta-epidemiological study comparing intervention effect estimates between CRTs and IRTs. Methods All Cochrane MAs including at least one CRT and one IRT, published between 1 January 2010 and 31 December 2014, were included. For each MA, we estimated a ratio of odds ratios (ROR) for binary outcomes or a difference of standardized differences (DSMD) for continuous outcomes, where less than 1 (or 0, respectively) indicated a greater intervention effect estimate with CRTs. Results Among 1301 screened reviews, we selected 121 MAs, of which 76 had a binary outcome and 45 had a continuous outcome. For binary outcomes, intervention effect estimates did not differ between CRTs and IRTs [ROR 1.00, 95% confidence interval (0.93 to 1.08)]. Subgroup and adjusted analyses led to consistent results. For continuous outcomes, the DSMD was 0.13 (0.06 to 0.19). It was lower for MAs with a pharmacological intervention [-0.03, (-0.12 to 0.07)], an objective outcome [0.05, (-0.08 to 0.17)] or after adjusting for trial size [0.06, (-0.01 to 0.15)]. Conclusion For binary outcomes, CRTs and IRTs can safely be pooled in MAs because of an absence of systematic differences between effect estimates. For continuous outcomes, the results were less clear although accounting for trial sample sizes led to a non-significant difference. More research is needed for continuous outcomes and, meanwhile, MAs should be completed with subgroup analyses (CRTs vs IRTs).
Foods, macronutrients and breast cancer risk in postmenopausal women: a large UK cohort Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-08 Key T, Angela B, Bradbury K, et al.
BackgroundThe role of diet in breast cancer aetiology is unclear; recent studies have suggested associations may differ by estrogen receptor status.MethodsBaseline diet was assessed in 2000–04 using a validated questionnaire in 691 571 postmenopausal UK women without previous cancer, who had not changed their diet recently. They were followed by record linkage to national cancer and death databases. Cox regression yielded adjusted relative risks for breast cancer for 10 food items and eight macronutrients, subdivided mostly into five categories of baseline intake. Trends in risk across the baseline categories were calculated, assigning re-measured intakes to allow for measurement error and changes in intake over time; P-values allowed for multiple testing.ResultsWomen aged 59.9 (standard deviation (SD 4.9)) years at baseline were followed for 12 (SD 3) years; 29 005 were diagnosed with invasive breast cancer. Alcohol intake had the strongest association with breast cancer incidence: relative risk (RR) 1.08 [99% confidence interval (CI) 1.05–1.11] per 10 g/day higher intake, P = 5.8 × 10−14. There were inverse associations with fruit: RR 0.94 (99% CI 0.92–0.97) per 100 g/day higher intake, P = 1.1 × 10−6, and dietary fibre: RR 0.91 (99% CI 0.87–0.96) per 5 g/day increase, P = 1.1 × 10−4. Fruit and fibre intakes were correlated (ρ = 0.62) and were greater among women who were not overweight, so residual confounding cannot be excluded. There was no heterogeneity for any association by estrogen receptor status.ConclusionsBy far the strongest association was between alcohol intake and an increased risk of breast cancer. Of the other 17 intakes examined, higher intakes of fruit and fibre were associated with lower risks of breast cancer, but it is unclear whether or not these associations are causal.
Adverse employment histories and health functioning: the CONSTANCES study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-11-06 Wahrendorf M, Hoven H, Goldberg M, et al.
Background With changing employment histories in European labour markets, occupational health research needs to be supplemented by an approach that integrates adverse characteristics of entire employment histories, in terms of precarious, discontinued and disadvantaged employment careers. We analyse associations of adverse employment histories and six measures of health functioning, including affective, physical and cognitive functioning. Methods We use baseline data from the CONSTANCES study with detailed retrospective data on previous employment histories that are linked to current health functioning among people aged 45–60 years (men = 15 134; women = 16 584). The following career characteristics are assessed (all referring to careers between ages 25 and 45 years): number of jobs with temporary contracts, number of job changes, number of unemployment periods, years out of work, mode occupational position and lack of job promotion. The measures of health functioning range from depressive symptoms, standing balance, walking speed, lung function, to verbal memory and semantic fluency. Results For both men and women, multilevel regressions (participant nested in health-examination centre) revealed that adverse employment histories are associated with poor health functioning later on, in particular persistent disadvantage in terms of low occupational position, repeated periods of unemployment and weak labour-market ties (years out of work). Findings remain consistent after excluding respondents who had a health-related career interruption or already retired before age 45 years and, additionally, after adjusting for age, partnership and education. Conclusion Findings call for increased intervention efforts among more disadvantaged groups of the labour market at early-career stages.
Statistical adjustment of culture-independent diagnostic tests for trend analysis in the Foodborne Diseases Active Surveillance Network (FoodNet), USA Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-03-19 Gu W, Dutta V, Patrick M, et al.
Background Culture-independent diagnostic tests (CIDTs) are increasingly used to diagnose Campylobacter infection in the Foodborne Diseases Active Surveillance Network (FoodNet). Because CIDTs have different performance characteristics compared with culture, which has been used historically and is still used to diagnose campylobacteriosis, adjustment of cases diagnosed by CIDT is needed to compare with culture-confirmed cases for monitoring incidence trends. Methods We identified the necessary parameters for CIDT adjustment using culture as the gold standard, and derived formulas to calculate positive predictive values (PPVs). We conducted a literature review and meta-analysis to examine the variability in CIDT performance and Campylobacter prevalence applicable to FoodNet sites. We then developed a Monte Carlo method to estimate test-type and site-specific PPVs with their associated uncertainties. Results The uncertainty in our estimated PPVs was largely derived from uncertainty about the specificity of CIDTs and low prevalence of Campylobacter in tested samples. Stable CIDT-adjusted incidences of Campylobacter cases from 2012 to 2015 were observed compared with a decline in culture-confirmed incidence. Conclusions We highlight the lack of data on the total numbers of tested samples as one of main limitations for CIDT adjustment. Our results demonstrate the importance of adjusting CIDTs for understanding trends in Campylobacter incidence in FoodNet.
Patterns of plant and animal protein intake are strongly associated with cardiovascular mortality: the Adventist Health Study-2 cohort Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-04-02 Tharrey M, Mariotti F, Mashchak A, et al.
Background Current evidence suggests that plant and animal proteins are intimately associated with specific large nutrient clusters that may explain part of their complex relation with cardiovascular health. We aimed at evaluating the association between specific patterns of protein intake with cardiovascular mortality. Methods We selected 81 337 men and women from the Adventist Health Study-2. Diet was assessed between 2002 and 2007, by using a validated food frequency questionnaire. Dietary patterns based on the participants’ protein consumption were derived by factor analysis. Cox regression analysis was used to estimate multivariate-adjusted hazard ratios (HRs) adjusted for sociodemographic and lifestyle factors and dietary components. Results There were 2276 cardiovascular deaths during a mean follow-up time of 9.4 years. The HRs for cardiovascular mortality were 1.61 [98.75% confidence interval (CI), 1.12 2.32; P-trend < 0.001] for the ‘Meat’ protein factor and 0.60 (98.75% CI, 0.42 0.86; P-trend < 0.001) for the ‘Nuts & Seeds’ protein factor (highest vs lowest quintile of factor scores). No significant associations were found for the ‘Grains’, ‘Processed Foods’ and ‘Legumes, Fruits & Vegetables’ protein factors. Additional adjustments for the participants’ vegetarian dietary pattern and nutrients related to cardiovascular disease outcomes did not change the results. Conclusions Associations between the ‘Meat’ and ‘Nuts & Seeds’ protein factors and cardiovascular outcomes were strong and could not be ascribed to other associated nutrients considered to be important for cardiovascular health. Healthy diets can be advocated based on protein sources, preferring low contributions of protein from meat and higher intakes of plant protein from nuts and seeds.
Physical activity and cause-specific mortality: the Rotterdam Study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-04-16 Koolhaas C, Dhana K, Schoufour J, et al.
BackgroundPhysical activity (PA) is associated with lower risk for all-cause mortality. However, in elderly people, it remains unknown which types of PA are associated with mortality and whether the association between PA and mortality differs by cause of death.MethodsWe assessed the association of total PA, walking, cycling, domestic work, sports and gardening with all-cause mortality, and the association of total PA with cause-specific mortality, using Cox proportional hazard models among 7225 older adults (mean age: 70 years) from the prospective population-based Rotterdam Study. Deaths were classified as due to cardiovascular diseases (CVDs), cancer, infections, external causes, dementia, chronic lung diseases or other causes. Activities were categorized into tertiles (lowest tertile as reference). To account for the possibility of reverse causation, we excluded the first 5 and 10 years of follow-up.ResultsOver a median of 13.1 years of follow-up (interquartile range: 8.4–14.6 years), 3261 participants died. The hazard ratios (HRs) and 95% confidence intervals (95% CIs) associated with high total PA compared with low were 0.69 (0.63, 0.75), 0.69 (0.58, 0.81), 0.44 (0.27, 0.71), 0.47 (0.32, 0.71) and 0.56 (0.46, 0.69) for mortality from all causes, CVDs, chronic lung diseases, infections and other causes, respectively. With longer exclusion times, the strength of these associations was attenuated. All PA types were associated with lower all-cause mortality risk.ConclusionsEngagement in higher PA levels was associated with lower risk of mortality from CVDs, chronic lung diseases, infections and other causes. Participating in any PA might reduce mortality risk in older adults.
Preterm infants have distinct microbiomes not explained by mode of delivery, breastfeeding duration or antibiotic exposure Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-04-20 Dahl C, Stigum H, Valeur J, et al.
BackgroundPreterm infants have low gut microbial diversity and few anaerobes. It is unclear whether the low diversity pertains to prematurity itself or is due to differences in delivery mode, feeding mode or exposure to antibiotics.MethodsThe Norwegian Microbiota Study (NoMIC) was established to examine the colonization of the infant gut and health outcomes. 16S rRNA gene Illumina amplicon-sequenced samples from 519 children (160 preterms), collected at 10 days, 4 months and 1 year postnatally, were used to calculate alpha diversity. Short-chain fatty acids (SCFA) were analysed with gas chromatography and quantified using flame ionization detection. We regressed alpha diversity on gestational age, taking into account possible confounding and mediating factors, such as breastfeeding and antibiotics. Taxonomic differences were tested using Analysis of Composition of Microbiomes (ANCOM) and SCFA profile (as a functional indicator of the microbiota) was tested by Wilcoxon rank-sum.ResultsPreterm infants had 0.45 Shannon units lower bacterial diversity at 10 days postnatally compared with infants born at term (95% confidence interval: –0.60, –0.32). Breastfeeding status and antibiotic exposure were not significant mediators of the gestational age–diversity association, although time spent in the neonatal intensive care unit was. Vaginally born, exclusively breastfed preterm infantss not exposed to antibiotics at 10 days postnatally had fewer Firmicutes and more Proteobacteria than children born at term and an SCFA profile indicating lower saccharolytic fermentation.ConclusionsPreterm infants had distinct gut microbiome composition and function in the early postnatal period, not explained by factors more common in preterms, such as shorter breastfeeding duration, more antibiotics or caesarean delivery.
Considerations of antiviral treatment to interrupt mother-to-child transmission of hepatitis B virus in China Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-05-10 Cui F, Woodring J, Chan P, et al.
Background Treating high-risk women with antivirals in their third trimester is a promising intervention to further reduce perinatal transmission in neonates born to hepatitis B surface antigen positive [HBsAg(+)] mothers. Methods We estimated the number of perinatal infections based on coverage and effectiveness of hepatitis B immunization. We compared cost-effectiveness of different approaches to identify high-risk women for antiviral treatment, by region and urban/rural residence. Results Of the 16.59 million live births in 2015, 1.04 million infants (6.3%) were born to HBsAg(+) mothers and 268 201 infants (1.6%) to HBsAg(+) and HBeAg(+) dual-positive mothers. Despite immunoprophylaxis, 51 478 perinatal hepatitis B virus (HBV) transmissions were estimated to have occurred from HBsAg and HBeAg dual-positive mothers in 2015. Using HBeAg or HBV viral load testing to identify high-risk pregnant women and to treat them with Tenofovir, the incremental cost ranged from US$68.2 million to US$90.3 million. Assuming HBV viral load testing is available and used to guide treatment and all women with HBV viral loads >200 000 IU/ml are treated, 25 912 infections would be averted at a projected cost of US$3500 per infection averted. Conclusions Identifying high-risk pregnant women and providing them with antiviral treatment is feasible and cost-effective to interrupt perinatal HBV transmissions. Policy options should be urgently explored in order for China to reach the HBV elimination goal of 0.1% prevalence among children by 2030.
The impact of multidimensional disadvantage over childhood on developmental outcomes in Australia Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-05-29 Goldfeld S, O’Connor M, Chong S, et al.
Background Understanding the relationship between different aspects of disadvantage over time and domains of child development will facilitate the formulation of more precise policy responses. We examined the association between exposure to aspects of disadvantage over the childhood period (from 0–9 years) and child development at 10–11 years. Methods We used data from the nationally representative birth cohort of the Longitudinal Study of Australian Children (n = 4979). Generalized linear models with log-Poisson link were used to estimate the association between previously derived disadvantage trajectories (in each of four lenses of sociodemographic, geographic environments, health conditions and risk factors, and a composite of these) and risk of poor child developmental outcomes. Population-attributable fractions were calculated to quantify the potential benefit of providing all children with optimal conditions for each developmental outcome. Results Trajectories of disadvantage were associated with developmental outcomes: children in the most disadvantaged composite trajectory had seven times higher risk of poor outcomes on two or more developmental domains, compared with those most advantaged. Trajectories of disadvantage in different lenses were varyingly associated with the child development domains of socio-emotional adjustment, physical functioning and learning competencies. Exposure to the most advantaged trajectory across all lenses could reduce poor developmental outcomes by as much as 70%. Conclusions Exposure to disadvantage over time is associated with adverse child development outcomes. Developmental outcomes varied with the aspects of disadvantage experienced, highlighting potential targets for more precise policy responses. The findings provide evidence to stimulate advocacy and action to reduce child inequities.
Maternal antibiotic exposure during pregnancy and hospitalization with infection in offspring: authors’ reply Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-05-30 Miller J, Wu C, Pedersen L, et al.
We thank Chandrakumar et al. for their interest in our work.1 We acknowledge some issues raised in the original manuscript and will address other points in detail that the manuscript word limit precluded.
Maternal antibiotic exposure during pregnancy and hospitalization with infection in offspring Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-05-31 Chandrakumar A, Bhardwaj A, Jong G.
The recently published study by Miller et al.1 reported that antibiotic exposure before or during pregnancy was associated with an increased risk of childhood infection-related hospitalizations. They attributed this risk to a complex interplay of perturbed maternal microbiota, environmental factors and immunogenetics. Although genetics and environmental factors are undeniably significant elements, the causative impact of maternal antibiotic exposure before and during pregnancy could be questioned.
Antibiotics, acetaminophen and infections during prenatal and early life in relation to type 1 diabetes Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-01 Tapia G, Størdal K, Mårild K, et al.
Background Infections in early life have been linked to type 1 diabetes (T1D) risk, but no previous study has comprehensively analysed exposure to antibiotics, acetaminophen and infections during pregnancy and early childhood in relation to offspring risk of T1D. Methods Participants in the Norwegian Mother and Child Cohort Study (n = 114 215 children, of whom 403 children were diagnosed with T1D) reported infections and medication use through repeated questionnaires from pregnancy until the children were 18 months old. Adjusted hazard ratios (aHR) for offspring T1D were estimated through Cox regression adjusted for child’s sex, maternal age and parity, maternal T1D, smoking in pregnancy, education level, pre-pregnancy body mass index (BMI) and birthweight. Antibiotic use was also analysed in a population-based register cohort of 541 036 children of whom 836 developed T1D. Results Hospitalization for gastroenteritis during the first 18 months of life was associated with increased risk (aHR 2.27, 95% CI 1.21 − 4.29, P = 0.01) of T1D. Childhood infections not requiring hospitalization, or any kind of maternal infection during pregnancy, did not predict offspring risk of T1D. Antibiotic or acetaminophen use in pregnancy, or child`s use in early childhood, was not associated with risk of T1D. Conclusions Our study, which is population-based and the largest of its kind, did not find support for general early life infections, infection frequency or use of antibiotics or acetaminophen to play a major role in childhood T1D. Hospital admission for gastroenteritis was associated with T1D risk, but must be interpreted cautiously due to scarcity of cases.
Comparison of cognitive and physical functioning of Europeans in 2004-05 and 2013 Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-01 Ahrenfeldt L, Lindahl-Jacobsen R, Rizzi S, et al.
Background Adult mortality has been postponed over time to increasingly high ages. However, evidence on past and current health trends has been mixed, and little is known about European disability trends. Methods In a cross-sectional setting, we compared cognitive and physical functioning in same-aged Europeans aged 50+ between 2004–05 (wave 1; n = 18 757) and 2013 (wave 5 refresher respondents; n = 16 696), sourced from the Survey of Health, Ageing and Retirement in Europe (SHARE). Results People in 2013 had better cognitive function compared with same-aged persons in 2004–05, with an average difference of approximately one-third standard deviation. The same level of cognitive function in 2004–05 at age 50 was found in 2013 for people who were 8 years older. There was an improvement in cognitive function in all European regions. Mean grip strength showed an improvement in Northern Europe of 1.00 kg [95% confidence interval (CI) 0.65; 1.35] and in Southern Europe of 1.68 kg (95% CI 1.14; 2.22), whereas a decrease was found in Central Europe (-0.80 kg; 95% CI −1.16; −0.44). We found no overall differences in activities of daily living (ADL), but small improvements in instrumental activities of daily living (IADL) in Northern and Southern Europe, with an improvement in both ADL and IADL from age 70 in Northern Europe. Conclusions Our results indicate that later-born Europeans have substantially better cognitive functioning than earlier-born cohorts. For physical functioning, improvements were less clear, but for Northern Europe there was an improvement in ADL and IADL in the oldest age groups.
Periodontal treatment among mothers with mild to moderate periodontal disease and preterm birth: reanalysis of OPT trial data accounting for selective survival Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-02 Merchant A, Sutherland M, Liu J, et al.
Background The Obstetrics and Periodontal Therapy (OPT) study, a randomized controlled trial, reported no effect of periodontal treatment on preterm birth. Even though there were more spontaneous abortions or stillbirths in the control group, sensitivity analyses using conventional approaches did not change the results. The development of newer epidemiological methods to assess bias caused by the truncated outcome, and the availability of OPT study data in the public domain, allowed us to reanalyse these data. Methods We used the survivor average causal effect (SACE), also known as the principal strata effect, to correct potential bias resulting from unequal survival of fetuses in the treatment and control arms of the OPT study. Results The risks of preterm and spontaneous abortions or stillbirths were respectively 49/413 (11.86%) and 5/413 (1.21%) in the periodontal treatment group, and 52/410 (12.68%) and 14/410 (3.33%) respectively in the control group. The risk differences (%) comparing periodontal treatment and control groups were -0.82%: 95% confidence interval (CI) -5.30% to 3.67% for preterm birth, and -2.12%: 95% CI -4.14% to -0.11% for spontaneous abortions or stillbirths before correction. Risk differences for preterm birth comparing periodontal treatment and control groups increased in magnitude, reached statistical significance and showed a beneficial effect of periodontal treatment after correction for bias using SACE. Conclusions Periodontal treatment provided to mothers with mild to moderate periodontal disease before 21 weeks of gestation may prevent preterm births.
Medical journals should embrace preprints to address the reproducibility crisis Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-03 Oakden-Rayner L, Beam A, Palmer L.
Preprints can help detect flaws that might otherwise escape the notice of a conventional peer review process
Excessive daytime sleepiness, objective napping and 11-year risk of Parkinson’s disease in older men Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-04 Leng Y, Goldman S, Cawthon P, et al.
Background It is unknown whether subjective daytime sleepiness or objective napping could precede the risk of Parkinson’s disease (PD) in the long term. Methods We studied 2920 men (mean age 76 years) without a history of PD and followed them for 11 years. Excessive daytime sleepiness (EDS) was defined as having an Epworth Sleepiness Scale score >10. Objective naps were defined as ≥5 consecutive minutes of inactivity as measured by actigraphy, and napping duration was the accumulated time of naps outside the main sleep period. We used logistic regression to compare PD risk across four groups: no EDS& napping <1 h/day (N = 1739, 59.5%; referent group), EDS& napping <1 h/day (N = 215, 7.4%), no EDS& napping ≥ 1 h/day (N= 819, 28.1%) and EDS& napping ≥ 1 h/day (N = 147, 5.0%). Results We identified 106 incident PD cases over 11 years. After multivariable adjustment, men with napping ≥ 1h/day alone were twice as likely [odds ratio (OR) = 1.96, 95% confidence interval (CI) 1.25–3.08], and men with both EDS and napping ≥ 1 h/day were almost three times as likely to develop PD (2.52, 1.21–5.27), compared with the referent group. Compared with those with naps for <30 min, men who napped for ≥1 h/day had more than double the risk of PD. No association was found for EDS alone and PD risk. Further adjustment for chronotype and circadian stability, or excluding PD cases identified within 2 years after napping measurements, showed similar results. Conclusions Objective long napping rather than subjective EDS was prospectively associated with a higher risk of PD in older men. Objective measures of napping might be valuable as a preclinical marker for PD.
Impact of placebo arms on outcomes in antidepressant trials: systematic review and meta-regression analysis Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-06 Salanti G, Chaimani A, Furukawa T, et al.
Background There is debate in the literature as to whether inclusion of a placebo arm may alter characteristics of antidepressant trials. However, previous research has focused on response rates of various antidepressants on average only, ignoring potential differences among drugs or other aspects of trial findings. Little is known about the impact of a placebo arm on all-cause dropout and dropout due to adverse events. Methods We carried out a systematic review of published and unpublished double-blind randomized controlled trials (RCTs) for the acute treatment of unipolar major depression (update: January 2016). The probability of being allocated to placebo (π) was the exposure of interest, and we examined its influence on responders (efficacy), all-cause dropouts (acceptability) and dropouts due to adverse events (tolerability), while accounting for differences in drugs, trials and patient characteristics in multivariate random effects meta-regression. Results We included 421 studies (68 305 participants) comparing 16 antidepressants or placebo; π ranged from 20% to 50%. Response rate was lower [risk ratio (RR) 0.87; 95% confidence interval (CI) 0.83, 0.92] and all-cause dropout rate higher (RR 1.19; 95% CI 1.08, 1.31) for the same antidepressants in placebo-controlled trials compared with head-to-head trials. The probability of responding decreased by 3% (95% CI 2–5%) for every 10% increase in π, whereas the risk of all-cause dropout increased by 4% (95% CI 1–7%). Tolerability was unaffected by π. Response rate was inversely correlated with dropouts due to any cause (correlation coefficient −0.48; 95% CI −0.58, −0.36) and due to adverse events (−0.34; 95% CI −0.44, −0.23). Conclusions For the same antidepressant, response rate was on average smaller and dropouts higher when placebo was included; however, no association was found with dropouts due to adverse events. Decreased patient expectations, larger dropout rates and use of inappropriate statistical methods to impute missing data may explain this phenomenon. The findings call for caution in the integration of randomized evidence involving placebo arms.
The betaboost package—a software tool for modelling bounded outcome variables in potentially high-dimensional epidemiological data Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-13 Mayr A, Weinhold L, Hofner B, et al.
Motivation To provide an integrated software environment for model fitting and variable selection in regression models with a bounded outcome variable. Implementation The proposed modelling framework is implemented in the add-on package betaboost of the statistical software environment R. General features The betaboost methodology is based on beta-regression, which is a state-of-the-art method for modelling bounded outcome variables. By combining traditional model fitting techniques with recent advances in statistical learning and distributional regression, betaboost allows users to carry out data-driven variable and/or confounder selection in potentially high-dimensional epidemiological data. The software package implements a flexible routine to incorporate linear and non-linear predictor effects in both the mean and the precision parameter (relating inversely to the variance) of a beta-regression model. Availability The software is hosted publicly at [http://github.com/boost-R/betaboost] and has been published under General Public License (GPL) version 3 or newer.
A Bayesian approach to investigate life course hypotheses involving continuous exposures Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-14 Madathil S, Joseph L, Hardy R, et al.
Background Different hypotheses have been proposed in life course epidemiology on how a time-varying exposure can affect health or disease later in life. Researchers are often interested in investigating the probability of these hypotheses based on observed life course data. However, current techniques based on model/variable selection do not provide a direct estimate of this probability. We propose an alternative technique for a continuous exposure, using a Bayesian approach that has specific advantages, to investigate which life course hypotheses are supported by the observed data. Methods We demonstrate the technique, the relevant life course exposure model (RLM), using simulations. We also analyse data from a case-control study on risk factors of oral cancer, with repeated measurements of betel quid chewing across life. We investigate the relative importance of chewing one quid of betel per day, at three life periods: ≤20 years, 21–40 years and above 40 years of age, on the risk of developing oral cancer. Results RLM was able to correctly identify the life course hypothesis under which the data were simulated. Results from the case-control study showed that there was 74.3% probability that betel quid exposure earlier in life, compared with later, results in higher odds of developing oral cancer later in life. Conclusions RLM is a useful option to identify the life course hypothesis supported by the observed data prior to the estimation of a causal effect.
A Bayesian approach to synthesize estimates of the size of hidden populations: the Anchored Multiplier Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-21 Wesson P, Mirzazadeh A, McFarland W.
Background The multiplier method is one of the most frequently used population size estimation (PSE) methods for key populations, yet estimates from this method are often inconsistent with each other, other PSE methods and local knowledge. We developed a novel Bayesian approach, the ‘Anchored Multiplier’, which synthesizes estimates from multipliers coupled to an a priori estimate to arrive at a single consensus estimate and credible range. Methods Data for size estimation were collected from three cross-sectional bio-behavioural surveillance studies of people who inject drugs (PWID) in San Francisco, CA, USA (2005, 2009 and 2012). We demonstrate the application of the Anchored Multiplier and a Variance Adjusted-Anchored Multiplier using PSE produced by multipliers in the three surveys and the literature for the USA. Size estimates were compared with estimates from other available PSE methods. Results Using the Anchored Multiplier, we estimated the PWID population made up 2.41% [95% credible interval (CI): 1.9–2.85] of the adult population in 2005, 2.1% (95% CI: 1.8–2.48) in 2009 and 2.3% (95% CI: 2.03–2.61) in 2012. The Variance Adjusted-Anchored Multiplier calculated similar point estimates, with wider 95% credible intervals. Credible intervals from both approaches were substantially narrower than from other standard PSE methods and, unlike other methods, indicated that the prevalence of PWID was stable over time. Conclusions The Anchored Multiplier is a promising new approach to size estimation, which generates a single estimate to inform programmatic strategies to counter the HIV epidemic, and provides a robust denominator to quantify the burden of disease for key populations.
Atrial fibrillation: is there enough evidence to recommend opportunistic or systematic screening? Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-21 Orchard J, Lowres N, Neubeck L, et al.
Atrial fibrillation (AF) is the most common heart arrhythmia,1 the prevalence rising with age to 18% for those aged ≥85 years.2 It is associated with a 5-fold higher likelihood of stroke, a doubling of mortality and an increased likelihood of heart failure, myocardial infarction and dementia.3,4
Population mobility reductions associated with travel restrictions during the Ebola epidemic in Sierra Leone: use of mobile phone data Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-26 Peak C, Wesolowski A, zu Erbach-Schoenberg E, et al.
Background Travel restrictions were implemented on an unprecedented scale in 2015 in Sierra Leone to contain and eliminate Ebola virus disease. However, the impact of epidemic travel restrictions on mobility itself remains difficult to measure with traditional methods. New ‘big data’ approaches using mobile phone data can provide, in near real-time, the type of information needed to guide and evaluate control measures. Methods We analysed anonymous mobile phone call detail records (CDRs) from a leading operator in Sierra Leone between 20 March and 1 July in 2015. We used an anomaly detection algorithm to assess changes in travel during a national ‘stay at home’ lockdown from 27 to 29 March. To measure the magnitude of these changes and to assess effect modification by region and historical Ebola burden, we performed a time series analysis and a crossover analysis. Results Routinely collected mobile phone data revealed a dramatic reduction in human mobility during a 3-day lockdown in Sierra Leone. The number of individuals relocating between chiefdoms decreased by 31% within 15 km, by 46% for 15–30 km and by 76% for distances greater than 30 km. This effect was highly heterogeneous in space, with higher impact in regions with higher Ebola incidence. Travel quickly returned to normal patterns after the restrictions were lifted. Conclusions The effects of travel restrictions on mobility can be large, targeted and measurable in near real-time. With appropriate anonymization protocols, mobile phone data should play a central role in guiding and monitoring interventions for epidemic containment.
The impact of social housing on mental health: longitudinal analyses using marginal structural models and machine learning-generated weights Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-06-26 Bentley R, Baker E, Simons K, et al.
Background Social housing may provide an affordable and secure residential environment, but has also been associated with stigma, poor housing conditions and locational disadvantage. We examined the cumulative effect of additional years, and tenure security (number of transitions in/out), of social housing on mental health in a large cohort of lower-income Australians. Methods We analysed a longitudinal panel survey that annually collected information on tenure and health from 2001 to 2013. To address the time-varying effect of previous health on social housing occupancy, we used marginal structural models. Stabilized inverse probabilities of treatment weights were generated using ensemble learning to improve prediction. To address remaining residual imbalance across covariates, double adjustment was made by additionally including baseline covariates in models. Mental health was measured using the Mental Health Short-Form summary measure of the SF-36 (MH), and psychological distress was measured using the Kessler Psychological Distress Scale (K10). Results People who had continuous exposure to social housing had worse mental health on average than people continuously occupying other tenures. The worst mental health outcomes, however, were observed for people who made multiple transitions. Mental health deteriorated and psychological distress increased with number of transitions: MH −1.04 [95% confidence interval (CI) −2.16; 0.09) and K10 0.56 (95% CI 0.12; 1.00). Estimates are in the order of 6% (MH) and 9% (K10) of one standard deviation for each measure. Conclusions The more transitions people made in/out of social housing, the greater the impact on mental health and psychological distress, supporting the case for provision of more stable forms of social housing.
Longitudinal associations between having an adult child migrant and depressive symptoms among older adults in the Mexican Health and Aging Study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-02 Torres J, Rudolph K, Sofrygin O, et al.
Background Migration may impact the mental health of family members who remain in places of origin. We examined longitudinal associations between having an adult child migrant and mental health, for middle-aged and older Mexican adults accounting for complex time-varying confounding. Methods Mexican Health and Aging Study cohort (N = 11 806) respondents ≥50 years completed a 9-item past-week depressive symptoms scale; scores of ≥5 reflected elevated depressive symptoms. Expected risk differences (RD) for elevated depressive symptoms at each wave due to having at least one (versus no) adult child migrant in the US or in another Mexican city were estimated with longitudinal targeted maximum likelihood estimation. Results Women with at least one adult child in the US had a higher adjusted baseline prevalence of elevated depressive symptoms (RD: 0.063, 95% CI: 0.035, 0.091) compared to women with no adult children in the US. Men with at least one child in another Mexican city at all three study waves had a lower adjusted prevalence of elevated depressive symptoms at 11-year follow-up (RD: −0.042, 95% CI: −0.082, −0.003) compared to those with no internal migrant children over those waves. For men and women with ≤3 total children, adverse associations between having an adult child in the US and depressive symptoms persisted beyond baseline. Conclusions Associations between having an adult child migrant and depressive symptoms varied by respondent gender, family size, and the location of the child migrant. Trends in population aging and migration bring new urgency to examining associations with other outcomes and in other settings.
Reflection on modern methods: selection bias—a review of recent developments Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-03 Infante-Rivard C, Cusson A.
Selection bias remains a more difficult bias to understand than confounding or measurement error. Past definitions have not always been illuminating and a simple method (such as the change-in-estimate method for confounding) has not been available to determine its presence and magnitude in the study sample. A better understanding of the nature of the bias has led to the definition of endogenous selection bias. It is the result of conditioning on a collider variable, itself caused by two other variables; the latter variables become spuriously associated. Conditioning on a variable in the analysis that is a collider or on an indicator of sample selection has the same effect. Note that selection bias is possible even in the absence of a collider, but in the presence of endogenous selection bias, the concern is whether it is possible to identify a causal effect in the sample. Conditions have been outlined to determine that. However, even if conditions are met to identify a causal effect in the study sample, its generalization to a defined target population is not a given.We discuss the concept of endogeneity and the sources of endogenous selection bias in observational studies. We then briefly address the terms generalizability, target population (or alternative formulations) and transportability. We outline the explicit conditions to identify causal effects in studies affected by selection bias: they involve exchangeability between exposed and unexposed and exchangeability between sampled and unsampled. We briefly describe methods to generalize estimated causal effects to the target population. The latter usually require data from the target population. Finally we discuss sensitivity analyses; some are limited to providing an indication of the presence and direction of the bias and others can provide corrected estimates with user-supplied selection bias parameters.
Physical activity and generalized anxiety disorder: results from The Irish Longitudinal Study on Ageing (TILDA) Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-03 McDowell C, Dishman R, Vancampfort D, et al.
Background Generalized anxiety disorder (GAD) is prevalent and costly. Physical activity (PA) may protect against other mental health disorders, including depression, but its protective effect on GAD remains under-studied in the general population and unstudied among older adults. Therefore, the present study examines associations between meeting World Health Organization PA guidelines (i.e. ≥150 min of moderate PA, ≥75 min of vigorous PA or ≥600MET min of moderate and vigorous PA weekly) and the prevalence of probable GAD and incidence of GAD. Methods Participants (n = 3950; 56.2% female) aged ≥50 years completed the short-form International Physical Activity Questionnaire and the abbreviated Penn State Worry Questionnaire at baseline and the Composite International Diagnostic Interview – Short Form to clinically assess GAD 2 years later. Prospective analyses included participants without probable GAD at baseline (n = 3236). Results Prevalence and incidence of GAD were 18.1% (n = 714) and 0.9% (n = 29), respectively. More respondents with GAD were female (72.2% vs 52.7%), aged 50–59 years (51.7% vs 38.7%), had normal waist circumference (52.7% vs 47.8) and smoked (20.4% vs 13.3%; all P<0.05). Meeting PA guidelines was associated with 25% and 63% lower odds of prevalent [odds ratio (OR) = 0.75, 95% confidence interval: 0.64 to 0.88] and incident (OR = 0.37, 0.17 to 0.85) GAD, respectively, in crude models, and 17% and 57% lower odds of prevalent (OR = 0.83, 0.70 to 0.98) and incident (OR = 0.43, 0.19 to 0.99) GAD, respectively, following adjustment for age, sex, waist circumference, social class and smoking. Conclusions In addition to established physical health benefits of PA, the present findings support the importance of increasing PA at the population-level for mental health.
Do employment factors reduce the effect of low education on mental health? A causal mediation analysis using a national panel study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-09 Milner A, Blakely T, Disney G, et al.
Background Young people with low education have worse health than those with higher education. This paper examined the extent to which employment and income reduced the adverse effects of low education on mental health among people aged 20–35 years. Methods We used causal mediation analyses to estimate the total causal effect (TCE) of low education on mental health and to decompose the effect into the natural direct effect (NDE) and the natural indirect effect (NIE) through two mediators examined sequentially: employment (labour-force participation/occupation skill level) and income. Three waves of the Household, Income and Labour Dynamics in Australia (HILDA) survey (2012–14) were used to establish a temporal sequence between low education (not completing high school), mediators and mental health [the Mental Health Inventory (MHI-5)] among participants aged 20–35 years. Among those who were employed, we conducted further analyses examining the effect of job characteristics as a mediator of the relationship between low education and mental health. Results The TCE of low education on the MHI-5 was –3.61 [95% confidence interval (CI) –5.30 to –1.92]. The NIE through labour force status and occupational skill level was –1.09 (95% CI –2.29 to 0.10) and –1.49 (95% CI –2.79 to –0.19) through both labour-force status/occupational skill level and income, corresponding to a percentage mediated of 41%. Among the employed, education had a much smaller effect on the MHI-5. Conclusions Improving employment opportunities could reduce nearly half of the adverse effects of low education on the mental health of young people.
Development and validation of alternative cardiovascular risk prediction equations for population health planning: a routine health data linkage study of 1.7 million New Zealanders Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-12 Mehta S, Jackson R, Pylypchuk R, et al.
Background Cardiovascular disease (CVD) risk prediction equations are primarily used in clinical settings to inform individual risk management decisions. We sought to develop and validate alternative equations derived solely from linked routinely collected national health data that could be applied countrywide to inform population health planning. Methods Individual-level linkage of eight administrative health datasets identified all New Zealand residents aged 30–74 years in contact with publicly funded health services during 2006 with no previous hospitalizations for CVD or heart failure, and with complete data on eight pre-specified predictors. The linked health datasets encompassed demographic characteristics, hospitalizations, outpatient visits, primary care enrolment, primary care reimbursement, community laboratory requests, community pharmaceutical dispensing and mortality. Sex-specific Cox models were developed to estimate the risk of CVD death or hospitalization within 5 years and included sex, age, ethnicity, level of deprivation, diabetes, previous hospitalization for atrial fibrillation and baseline preventive pharmacotherapy (blood-pressure-lowering, lipid-lowering and antiplatelet/anticoagulant medications) as predictors. Calibration and discrimination were assessed in the whole cohort, in 15-year age bands, in different ethnic groups, in quintiles of deprivation, according to baseline dispensing of pharmacotherapy, and in regional sub-populations. Results First CVD events occurred in 62 031 of the 1 746 695 people during 8 526 024 person-years of follow-up (mean = 4.8 years). Median 5-year CVD risk was 1.1% in women and 2.6% in men. In both sexes, the risk equations were well calibrated throughout the risk range and had good risk discrimination in the national, regional and ethnic populations, within 15-year age bands, in deprivation quintiles and according to baseline medication dispensing. Conclusions Robust policy-focused CVD risk equations can be developed solely from administrative health data to inform population health planning, and will complement CVD primary prevention at the individual level using clinical risk tools. Similar policy-focused equations could be replicated in countries and regions with linked administrative health datasets.
Commentary: The pros of plurality for tuberculosis burden estimates Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-12 Dodd P.
Tuberculosis (TB) is now reckoned to be the leading infectious cause of death.1 That multiple people die every minute from a cheaply curable disease, which has been reduced to incidence rates of below 0.01% per year in many rich countries, is plainly unacceptable. The evidence to support statements on the extent of the TB pandemic most often comes from the burden estimates released annually by the Global TB Programme at the World Health Organization (WHO).1 The other set of global TB disease burden estimates are those of the Global Burden of Disease studies from the Institute of Health Metrics and Evaluation (IHME), which include TB as part of a large range of causes of deaths and disability.2 Both sets of estimates for mortality rely on high quality vital registration systems in countries where these exist; unfortunately, in many high-TB-burden countries such systems are lacking, and differences in the modelling approaches used to leverage other data sources (and to some extent, the inclusion of additional mortality data such as verbal autopsy by IHME) lead to differences between the WHO and IHME estimates, particularly at the country level.
What is the true tuberculosis mortality burden? Differences in estimates by the World Health Organization and the Global Burden of Disease study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-12 García-Basteiro A, Brew J, Williams B, et al.
Background The World Health Organization (WHO) and the Global Burden of Disease (GBD) study at the Institute for Health Metrics and Evaluation (IHME) periodically provide global estimates of tuberculosis (TB) mortality. We compared the 2015 WHO and GBD TB mortality estimates and explored which factors might drive the differences. Methods We extracted the number of estimated TB-attributable deaths, disaggregated by age, HIV status, sex and country from publicly available WHO and GBD datasets for the year 2015. We ‘standardized’ differences between sources by adjusting each country’s difference in absolute number of deaths by the average number of deaths estimated by both sources. Results For 195 countries with estimates from both institutions, WHO estimated 1 768 482 deaths attributable to TB, whereas GBD estimated 1 322 916 deaths, a difference of 445 566 deaths or 29% of the average of the two estimates. The countries with the largest absolute differences in deaths were Nigeria (216 621), Bangladesh (49 863) and Tanzania (38 272). The standardized difference was not associated with HIV prevalence, prevalence of multidrug resistance or global region, but did show correlation with the case detection rate as estimated by WHO [r = −0.37, 95% confidence interval (CI): −049; −0.24] or, inversely, with case detection rate based on GBD data (r = 0.44, 95% CI: 0.31; 0.54). Countries with a recent national prevalence survey had higher standardized differences (higher estimates by WHO) than those without (P = 0.006). After exclusion of countries with recent prevalence surveys, the overall correlation between both estimates was r = 0.991. Conclusions A few countries account for the large global discrepancy in TB mortality estimates. The differences are due to the methodological approaches used by WHO and GBD. The use and interpretation of prevalence survey data and case detection rates seem to play a role in the observed differences.
Does selective survival before study enrolment attenuate estimated effects of education on rate of cognitive decline in older adults? A simulation approach for quantifying survival bias in life course epidemiology Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-13 Mayeda E, Filshtein T, Tripodis Y, et al.
Background The relationship between education and late-life cognitive decline is controversial. Selective survival between early life, when education is typically completed, and late life, when cognitive ageing studies take place, could attenuate effect estimates. Methods We quantified potential survival bias (collider-stratification bias) in estimation of the effect of education on late-life cognitive decline by simulating hypothetical cohorts of 20-year-olds and applying cumulative mortality from US life tables. For each of four causal scenarios (2000 replications each), we compared the estimated versus causal effect of education on cognitive decline over 9 years, starting at age 60, 75 or 90 in random samples of n = 2000 people who survived to each age. Results Effects of education on cognitive decline were underestimated when both education and U, another determinant of cognitive decline, influenced mortality (collider-stratification bias). The magnitude of bias was sensitive to the magnitude of the effect of U on cognitive decline and whether there was a multiplicative interaction between education and U on mortality. For example, when there was a multiplicative interaction between education and U on mortality, 95% confidence interval coverage of the causal effect ranged from 83.4% to 50.4% at age 60 and 25.8% to 0.2% at age 90. Conclusions Selective survival could lead to underestimation of effects of education on late-life cognitive decline. Our simulations map survival bias to testable assumptions about underlying causal structures.
Patterns of multimorbid health conditions: a systematic review of analytical methods and comparison analysis Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-16 Ng S, Tawiah R, Sawyer M, et al.
Background The latest review of studies on multimorbidity patterns showed high heterogeneity in the methodology for identifying groups of multimorbid conditions. However, it is unclear how analytical methods used influence the identified multimorbidity patterns. Methods We undertook a systematic review of analytical methods used to identify multimorbidity patterns in PubMed and EMBASE from their inception to January 2017. We conducted a comparison analysis to assess the effect the analytical methods had on the multimorbidity patterns identified, using the Australian National Health Survey (NHS) 2007–08 data. Results We identified 13 194 studies and excluded 13 091 based on titles/abstracts. From the full-text reviews of the 103 remaining publications, we identified 41 studies that used five different analytical methods to identify multimorbid conditions in the studies. Thirty-seven studies (90%) adopted either the factor-analysis or hierarchical-clustering methods, but heterogeneity arises for the use of different proximity measures within each method to form clusters. Our comparison analysis showed the variation in identified groups of multimorbid conditions when applying the methods to the same NHS data. We extracted main similarities among the groupings obtained by the five methods: (i) cardiovascular and metabolic diseases, (ii) mental health problems and (iii) allergic diseases. Conclusion We showed the extent of effects for heterogeneous analytical methods on identification of multimorbidity patterns. However, more work is needed to guide investigators for choosing the best analytical method to improve the validity and generalizability of findings. Investigators should also attempt to compare results obtained by various methods for a consensus grouping of multimorbid conditions.
Primary prevention of rheumatic fever in the 21st century: evaluation of a national programme Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-27 Jack S, Williamson D, Galloway Y, et al.
Background Acute rheumatic fever (ARF) has largely disappeared from high-income countries. However, in New Zealand (NZ) rates remain high in indigenous (Māori) and Pacific populations. In 2011, NZ launched an intensive and unparalleled primary Rheumatic Fever Prevention Programme (RFPP). We evaluated the impact of the school-based sore throat service component of the RFPP. Methods The evaluation used national trends of all-age first episode ARF hospitalisation rates before (2009–11) and after (2012–16) implementation of the RFPP. A retrospective cohort study compared first-episode ARF incidence during time-not-exposed (23 093 207 person-days) and time-exposed (68 465 350 person-days) with a school-based sore throat service among children aged 5–12 years from 2012 to 2016. Results Following implementation of the RFPP, the national ARF incidence rate declined by 28% from 4.0 per 100 000 [95% confidence interval (CI) 3.5–4.6] at baseline (2009–11) to 2.9 per 100 000 by 2016 (95% CI 2.4–3.4, P <0.01). The school-based sore throat service effectiveness overall was 23% [95% CI -6%–44%; rate ratio (RR) 0.77, 95% CI 0.56–1.06]. Effectiveness was greater in one high-risk region with high coverage (46%, 95% CI 16%–66%; RR 0.54, 95% CI 0.34–0.84). Conclusions Population-based primary prevention of ARF through sore throat management may be effective in well-resourced settings like NZ where high-risk populations are geographically concentrated. Where high-risk populations are dispersed, a school-based primary prevention approach appears ineffective and is expensive.
Investigating the relationship between fetal growth and academic attainment: secondary analysis of the Born in Bradford (BiB) cohort Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-07-27 Norris T, Johnson W, Petherick E, et al.
Background The relationship between ultrasongraphically derived estimates of fetal growth and educational attainment in the postnatal period is unknown. Results from previous studies focusing on cognitive ability, however, suggest there may be gestation-specific associations. Our objective was to model growth in fetal weight (EFW) and head circumference (HC) and identify whether growth variation in different periods was related to academic attainment in middle childhood. Methods Data come from the Born in Bradford (BiB) cohort study, which has performed data linkage to both routine antenatal scans and national academic attainment tests at age 6–7 years. Multilevel linear spline models were used to model EFW and HC. Random effects from these were related to Key Stage 1 (KS1) results in reading, writing, mathematics, science and a composite of all four (age 6–7 years), using ordinal logistic and logistic regression. Associations were adjusted for potential confounders, facilitated by directed acyclic graphs. Missing covariate data were imputed using multiple imputation. Results In all, 6995 and 8438 children had complete KS1, and EFW and HC data, respectively. Positive associations were observed between both fetal weight in early pregnancy (14 weeks) and EFW growth in mid-pregnancy (14-26 weeks) and the individual KS1 outcomes. Furthermore, after adjustment for previous size and confounders, a 1-z score increase in growth in mid-pregnancy was associated with an 8% increased odds of achieving the expected standard for all KS1 outcomes [odds ratio (OR): 1.08, 95% confidence interval (CI): 1.02; 1.13]. Similar results were observed for HC, with generally larger effect sizes. Smaller associations were observed with growth in the early-third trimester, with no associations observed with growth in the later-third trimester. Conclusions We observed consistent positive associations between fetal size and growth in early and mid-gestation and academic attainment in childhood. The smaller and null associations with growth in the early-third and later-third trimester, respectively, suggests that early-mid gestation may be a sensitive period for future cognitive development.
Reducing geographic inequalities in access times for acute treatment of myocardial infarction in a large country: the example of Russia Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-08-01 Timonin S, Kontsevaya A, McKee M, et al.
Background Russia has the largest area of any country in the world and has one of the highest cardiovascular mortality rates. Over the past decade, the number of facilities able to perform percutaneous coronary interventions (PCIs) has increased substantially. We quantify the extent to which the constraints of geography make equitable access to this effective technology difficult to achieve. Methods Hospitals performing PCIs in 2010 and 2015 were identified and combined with data on the population of districts throughout the country. A network analysis tool was used to calculate road-travel times to the nearest PCI facility for those aged 40+ years. Results The number of PCI facilities increased from 144 to 260 between 2010 and 2015. Overall, the median travel time to the closest PCI facility was 48 minutes in 2015, down from 73 minutes in 2010. Two-thirds of the urban population were within 60 minutes’ travel time to a PCI facility in 2015, but only one-fifth of the rural population. Creating 67 new PCI facilities in currently underserved urban districts would increase the population share within 60 minutes’ travel to 62% of the population, benefiting an additional 5.7 million people currently lacking adequate access. Conclusions There have been considerable but uneven improvements in timely access to PCI facilities in Russia between 2010 and 2015. Russia has not achieved the level of access seen in other large countries with dispersed populations, such as Australian and Canada. However, creating a relatively small number of further PCI facilities could improve access substantially, thereby reducing inequality.
To what extent is the association between disability and mental health in adolescents mediated by bullying? A causal mediation analysis Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-08-03 King T, Aitken Z, Milner A, et al.
Background Disability among adolescents is associated with both poorer mental health (MH) and higher levels of bullying-victimization. Bullying, therefore, conceivably mediates the association between disability and MH. Quantifying this pathway is challenging as the exposure (disability), mediator (bullying) and outcome (MH) are subjective, and subject to dependent measurement error if the same respondent reports on two or more variables. Methods Utilizing the counterfactual and potential outcomes approaches to causal mediation, we decomposed the total effect of disability on MH into natural indirect effects (through bullying) and natural direct effects (not through bullying) using a sample of 3409 adolescents. As the study included data from multiple informants (teacher, parent, adolescent) on the outcome (MH, as measured on the Strengths and Difficulties Questionnaire) and two informants (adolescent, parent) on the mediator (bullying), we assessed the influence of dependent measurement error. Results For preferred analysis (using parent-reported bullying and adolescent-reported MH), the total effect was a 2.18 [95% confidence interval (CI): 0.66–3.40] lower MH score for adolescents with a disability, compared with those with no disability (strength of association equivalent to 37% of the standard deviation for MH). Bullying explained 46% of the total effect. Use of adolescent-reported bullying with adolescent-reported MH produced similar results (37% mediation, 95% CI: 12–74%). Conclusions Disability exerts a detrimental effect on adolescent MH, and a large proportion of this appears to operate through bullying. This finding does not appear to be spurious due to dependent measurement error.
Significant cognitive delay among 3- to 4-year old children in low- and middle-income countries: prevalence estimates and potential impact of preventative interventions Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-08-06 Emerson E, Savage A, Llewellyn G.
Background We sought to: (i) estimate the prevalence of significant cognitive delay (a marked delay in the development of general cognitive functioning) among nationally representative samples of young children in middle- and low-income countries; (ii) estimate the total number of children under 5 years of age with significant cognitive delay living in low- and middle-income countries; and (iii) estimate the potential impact of five preventative interventions. Methods Secondary analysis of data collected in Rounds 4 and 5 of UNICEF’s Multiple Cluster Indicators Surveys in 51 countries involving 163 293 3- to 4-year-old children. Adjusted population-attributable fractions were used to estimate the potential impact of five interventions based on Sustainable Development Goals (SDGs). Results The prevalence of significant cognitive delay in 3- to 4-year-old children in middle- and low-income countries was 10.1% (95% confidence interval 9.7–10.4%). Prevalence was strongly inversely related to country economic wealth. The estimated total number of children under 5 with significant cognitive delay living in low- and middle-income countries was just under 55 million. This number could be reduced by over 60% if three separate SDGs were achieved; every mother had secondary-level education, every household had access to improved water and sanitation, and every child had an acceptable level of home stimulation. Conclusions Our results provide additional evidence in support of a range of specific preventative interventions in early childhood to reduce the loss of developmental potential among children in low- and middle-income countries.
Early childhood antibiotics use and autism spectrum disorders: a population-based cohort study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-08-07 Hamad A, Alessi-Severini S, Mahmud S, et al.
Background Changes in microbiota composition as a result of antibiotics use in early life has been proposed as a possible contributor in the aetiology of autism spectrum disorders (ASD). We aimed to examine the association between early life antibiotic exposure and risk of ASD. Methods This was a population-based cohort study which included all live births in Manitoba, Canada, between 1 April 1998 and 31 March 2016. We used administrative health data from the Manitoba Population Research Data Repository. Exposure was defined as having filled one or more antibiotic prescription during the first year of life. The main outcome was ASD diagnosis. Cox proportional hazards regression models were used to estimate the risk of developing ASD in the overall population and in a sibling cohort. Results Of all subjects in the cohort (n = 214 834), 94 024 (43.8%) filled an antibiotic prescription during the first year of life. During follow-up, 2965 children received an ASD diagnosis. Compared with children who did not use antibiotics during the first year of life, those who received antibiotics had a reduced risk of ASD [adjusted hazardz ratio (HR) 0.91, 95% confidence interval (CI) 0.84–0.99). Number of treatment courses and cumulative duration of antibiotic exposure were not associated with ASD. In the sibling-controlled analysis, early life antibiotic exposure was not associated with ASD (adjusted HR 1.03, 95% CI 0.86–1.23). Conclusions Our findings suggested no clinically significant association between early life antibiotics exposure and risk of autism spectrum disorders, and should provide reassurance to concerned prescribers and parents.
Development and validation of a predictive ecological model for TB prevalence Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-08-16 Alba S, Rood E, Bakker M, et al.
Background Nationally representative tuberculosis (TB) prevalence surveys provide invaluable empirical measurements of TB burden but are a massive and complex undertaking. Therefore, methods that capitalize on data from these surveys are both attractive and imperative. The aim of this study was to use existing TB prevalence estimates to develop and validate an ecological predictive statistical model to indirectly estimate TB prevalence in low- and middle-income countries without survey data. Methods We included national and subnational estimates from 30 nationally representative surveys and 2 district-level surveys in India, resulting in 50 data points for model development (training set). Ecological predictors included TB notification and programmatic data, co-morbidities and socio-environmental factors extracted from online data repositories. A random-effects multivariable binomial regression model was developed using the training set and was used to predict bacteriologically confirmed TB prevalence in 63 low- and middle-income countries across Africa and Asia in 2015. Results Out of the 111 ecological predictors considered, 14 were retained for model building (due to incompleteness or collinearity). The final model retained for predictions included five predictors: continent, percentage retreated cases out of all notified, all forms TB notification rates per 100 000 population, population density and proportion of the population under the age of 15. Cross-fold validations in the training set showed very good average fit (R-sq = 0.92). Conclusion Predictive ecological modelling is a useful complementary approach to indirectly estimating TB burden and can be considered alongside other methods in countries with limited robust empirical measurements of TB among the general population.
Reducing the global burden of poor oral health through school-based programmes Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-08-29 Macnab A, Mukisa R.
Globally, dental caries and gingivitis negatively impact upon the health and quality of life of countless children.1,2 Caries is the commonest preventable infectious disease affecting children worldwide.3 The causal agent, Streptococcus mutans, thrives in an acidic environment where sugar is available.4 Bacteria are trapped in deposits of plaque on the gum line and cause gum inflammation and chronic periodontal disease.
Response to: Antiviral treatment in pregnant women with chronic hepatitis B infection Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-31 Cui F, Xu F.
We are happy to respond to the questions raised by Peng and Du. As we described in our Methods,1 we had to estimate the prevalence of hepatitis B virus (HBV) infection of various serostatuses [e.g. proportion with hepatitis B surface antigen (HBsAg) and hepatitis B e-antigen (HBeAg) dual-positive serostatus] in order to estimate the number of pregnant women at high risk of perinatal HBV transmission. The prevalence of HBsAg and HBeAg dual-positive serostatus was estimated by age groups. For women aged 15–29 years, the estimate was based on the 2014 serosurvey2; for women 30 years of age or older, the prevalence was based on the calculated age in 2014 by shifting 8 years of the participant’s age from the 2006 survey to reflect age-related changes over the 8-year period from 2006 to 2014.1–3 The differences in percentages of those who were HBeAg-positive among 22–41 versus 30–49-year-olds in 2006 were assumed to be wholly due to seroconversion. In this reconstructed survey, the loss of HBeAg over time with ageing of the 2006 survey participants, as Peng and Du correctly point out, should be accounted for.
Antiviral treatment in pregnant women with chronic hepatitis B infection Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-31 Peng S, Du Y.
We read with interest the article by Cui et al.1 regarding antiviral treatment to interrupt mother-to-child transmission of hepatitis B virus (HBV) in China. Their study found that identifying high-risk pregnant women and providing them with antiviral treatment is advisable and cost-effective to interrupt mother-to-child transmission of HBV. Their results add value to the efforts to develop national and regional treatment programmes that will help to achieve the WHO global elimination goal of 0.1% hepatitis B surface antigen (HBsAg) prevalence among children by 2030.
Reducing contamination risk in cluster-randomized infectious disease-intervention trials Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-29 McCann R, van den Berg H, Takken W, et al.
Background Infectious disease interventions are increasingly tested using cluster-randomized trials (CRTs). These trial settings tend to involve a set of sampling units, such as villages, whose geographic arrangement may present a contamination risk in treatment exposure. The most widely used approach for reducing contamination in these settings is the so-called fried-egg design, which excludes the outer portion of all available clusters from the primary trial analysis. However, the fried-egg design ignores potential intra-cluster spatial heterogeneity and makes the outcome measure inherently less precise. Whereas the fried-egg design may be appropriate in specific settings, alternative methods to optimize the design of CRTs in other settings are lacking. Methods We present a novel approach for CRT design that either fully includes or fully excludes available clusters in a defined study region, recognizing the potential for intra-cluster spatial heterogeneity. The approach includes an algorithm that allows investigators to identify the maximum number of clusters that could be included for a defined study region and maintain randomness in both the selection of included clusters and the allocation of clusters to either the treatment group or control group. The approach was applied to the design of a CRT testing the effectiveness of malaria vector-control interventions in southern Malawi. Conclusions Those planning CRTs to evaluate interventions should consider the approach presented here during trial design. The approach provides a novel framework for reducing the risk of contamination among the CRT randomization units in settings where investigators determine the reduction of contamination risk as a high priority and where intra-cluster spatial heterogeneity is likely. By maintaining randomness in the allocation of clusters to either the treatment group or control group, the approach also permits a randomization-valid test of the primary trial hypothesis.
Body mass index trajectories across adulthood and smoking in relation to prostate cancer risks: the NIH-AARP Diet and Health Study Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-29 Kelly S, Lennon H, Sperrin M, et al.
Background Previously we showed that adulthood body mass index (BMI) trajectories that result in obesity were associated with elevated risks of fatal prostate cancer (PCA). To further explore this relationship, we conducted a study within the NIH-AARP Diet and Health Study. Methods Among 153 730 eligible men enrolled in the NIH-AARP cohort from 1995 to 1996 (median follow-up = 15.1 years), we identified 630 fatal PCA cases and 16 896 incident cases. BMI was assessed for ages 18, 35 and 50 and at study entry, enabling examination of latent class-identified BMI trajectories. Hazard ratios (HRs) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression. Results BMI at study entry (mean age = 63, HR = 1.12; 95% CI = 1.01, 1.24, per 5-unit increase) and maximum BMI during adulthood (HR = 1.12; 95% CI = 1.02, 1.24, per 5-unit increase) shared modest associations with increased risk of fatal PCA. Smoking status likely modified the relationship between BMI trajectories and fatal PCA (Pinteraction = 0.035 via change-in-estimate variable section, P=0.065 via full a priori model). Among never-smokers, BMI trajectory of normal weight to obesity was associated with increased risk of fatal disease (HR = 2.37; 95% CI = 1.38, 4.09), compared with the maintained normal weight trajectory, whereas there was no association among former or current-smokers. Total and non-aggressive PCA exhibited modest inverse associations with BMI at all ages, whereas no association was observed for aggressive PCA. Conclusions Increased BMI was positively associated with fatal PCA, especially among never-smokers. Future studies that examine PCA survival will provide additional insight as to whether these associations are the result of biology or confounding.
Methods to assess the contribution of diseases to disability using cross-sectional studies: comparison of different versions of the attributable fraction and the attribution method Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-29 Palazzo C, Yokota R, Ferguson J, et al.
Background This study aims to illustrate the differences between approaches proposed for apportioning disability to different diseases in a multicausal situation, i.e. the unadjusted attributable fraction (AF), the adjusted AF, the average AF and the attribution method (AM). This information is useful to better interpret results obtained from cross-sectional data and help policy makers decide on public health strategies. Methods Data for 29 931 individuals, representative of the French household population, who participated in the 2008–09 cross-sectional Disability-Health Survey, were included. Disability was defined as any limitation reported with the Global Activity Limitation Indicator. Unadjusted AFs were calculated using Levin’s formula. Adjusted AFs were estimated for each disease by calculating predicted probabilities of disability for each individual in the dataset, under the assumption that the individual is unexposed to this specific disease (logistic model). Average AFs are based on the same methodology, but have the additional advantage that the average AFs for different diseases sum to the total AF associated with eliminating all diseases. AM accounts for competing risks and partitions total disability prevalence into additive contributions of different diseases and background disability (additive model). Results All methods obtained similar results with respect to the estimates of the disease contribution to disability prevalences and to ranking of the diseases, except unadjusted AFs, as the method ignores multimorbidity. Confounders other than diseases, such as age and gender, should be accurately taken into account. Conclusions Conceptual differences, strengths and limitations of the different approaches were discussed.
Rapidly increasing body mass index among children, adolescents and young adults in a transitioning population, South Africa, 2008–15 Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-29 Sartorius B, Sartorius K, Taylor M, et al.
First published online: 14 December 2017, Int J Epidemiol, 2018, 47(3), 942–952, doi: https://doi.org/10.1093/ije/dyx263.
HIV testing and counselling couples together for affordable HIV prevention in Africa Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-24 Wall K, Inambao M, Kilembe W, et al.
Background The impact and cost-effectiveness of couples’ voluntary HIV counselling and testing (CVCT) has not been quantified in real-world settings. We quantify cost-per-HIV-infection averted by CVCT in Zambia from the donor’s perspective. Methods From 2010 to 2016, CVCT was established in 73 Zambian government clinics. The cost-per-HIV-infection averted (CHIA) of CVCT was calculated using observed expenditures and effectiveness over longitudinal follow-up. These observed measures parameterized hypothetical 5-year nationwide implementations of: ‘CVCT’; ‘treatment-as-prevention (TasP) for discordant couples’ identified by CVCT; and ‘population TasP’ for all HIV+ cohabiting persons identified by individual testing. Results In all, 207 428 couples were tested (US $52/couple). Among discordant couples in which HIV+ partners self-reported antiretroviral therapy (ART), HIV incidence was 8.5/100 person-years before and 1.8/100 person-years after CVCT (79% reduction). Corresponding reductions for non-ART-using discordant and concordant negative couples were 63% and 47%, respectively. CVCT averted an estimated 58% of new infections at US $659 CHIA. In nationwide implementation models, CVCT would prevent 17 times the number of infections vs ‘TasP for discordant couples’ at 86% of the cost, and nine times the infections vs ‘population TasP’ at 28% of the cost. Conclusions CVCT is a cost-effective, feasible prevention strategy in Zambia. We demonstrate the novel, added effectiveness of providing CVCT to ART users, for whom ART use alone only partially mitigated transmission risk. Our results indicate a major policy shift (supporting development of CVCT indicators, budgets and targets) and have clinical implications (suggesting promotion of CVCT in ART clinics as a high-impact prevention strategy).
Habitual sleep quality, plasma metabolites and risk of coronary heart disease in post-menopausal women Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-26 Huang T, Zeleznik O, Poole E, et al.
Background Epidemiologic studies suggest a strong link between poor habitual sleep quality and increased cardiovascular disease risk. However, the underlying mechanisms are not entirely clear. Metabolomic profiling may elucidate systemic differences associated with sleep quality that influence cardiometabolic health. Methods We explored cross-sectional associations between sleep quality and plasma metabolites in a nested case–control study of coronary heart disease (CHD) in the Women’s Health Initiative (WHI; n = 1956) and attempted to replicate the results in an independent sample from the Nurses’ Health Study II (NHSII; n = 209). A sleep-quality score (SQS) was derived from self-reported sleep problems asked in both populations. Plasma metabolomics were assayed using LC–MS with 347 known metabolites. General linear regression was used to identify individual metabolites associated with continuous SQS (false-discovery rate <0.05). Using least absolute shrinkage and selection operator (LASSO) algorithms, a metabolite score was created from replicated metabolites and evaluated with CHD risk in the WHI. Results After adjusting for age, race/ethnicity, body mass index (BMI) and smoking, we identified 69 metabolites associated with SQS in the WHI (59 were lipids). Of these, 16 were replicated in NHSII (15 were lipids), including 6 triglycerides (TAGs), 4 phosphatidylethanolamines (PEs), 3 phosphatidylcholines (PCs), 1 diglyceride (DAG), 1 lysophosphatidylcholine and N6-acetyl-L-lysine (a product of histone acetylation). These metabolites were consistently higher among women with poorer sleep quality. The LASSO selection resulted in a nine-metabolite score (TAGs 45: 1, 48: 1, 50: 4; DAG 32: 1; PEs 36: 4, 38: 5; PCs 30: 1, 40: 6; N6-acetyl-L-lysine), which was positively associated with CHD risk (odds ratio per SD increase in the score: 1.16; 95% confidence interval: 1.05, 1.28; p = 0.0003) in the WHI after adjustment for matching factors and conventional CHD risk factors. Conclusions Differences in lipid metabolites may be an important pathogenic pathway linking poor habitual sleep quality and CHD risk.
Causal models adjusting for time-varying confounding—a systematic review of the literature Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-24 Clare P, Dobbins T, Mattick R.
Background Obtaining unbiased causal estimates from longitudinal observational data can be difficult due to exposure-affected time-varying confounding. The past decade has seen considerable development in methods for analysing such complex longitudinal data. However, the extent to which those methods have been implemented is unclear. This study describes and characterizes the state of the field in methods adjusting for exposure-affected time-varying confounding, and examines their use in the literature. Methods We systematically reviewed the literature from 2000 to 2016 for studies adjusting for time-dependent confounding, including use of specific methods like inverse probability of treatment weighting (IPTW). Articles were coded based on the methods used and, for applied articles, the topic areas covered. Results We screened 4239 abstracts, and subsequently reviewed 1100 articles, leaving 542 relevant articles in the analyses. The number of published articles increased from two in 2000, to 112 in 2016. This increase was primarily in applied articles using IPTW, which increased from one study in 2000, to 90 in 2016. Of the 432 studies with applications to observed data, 60.9% were on at least one of: HIV (30.6%), cardiopulmonary health (13.2%), kidney disease (11.8%) or mental health (10.0%). Conclusions There has been marked growth in reports addressing exposure-affected time-varying confounding. This was driven by work in a small number of topic areas, with other areas showing relatively little uptake. In addition, despite developments in more advanced methods such doubly robust techniques and estimation via machine learning, implementation has been largely concentrated on the simpler, yet potentially less robust, IPTW.
A test of the epidemiological paradox in a context of forced migration: low birthweight among Syrian newborns in Lebanon Int. J. Epidemiol. (IF 8.36) Pub Date : 2018-10-23 Abdulrahim S, El Rafei R, Beydoun Z, et al.
Background Studies on immigrants revealed an epidemiological paradox whereby low-socioeconomic status (SES) immigrant mothers exhibit favourable birth outcomes compared with native-born mothers. We tested the epidemiological paradox in a context of forced migration, comparing associations of low birthweight (LBW) and maternal SES between Syrian and Lebanese newborns in Lebanon. Methods We used data from the National Collaborative Perinatal Neonatal Network (NCPNN) of 31 Lebanese hospitals, including 45 442 Lebanese and 4910 Syrian neonates born 2011–13. We assessed associations between LBW and maternal SES for both groups. Logistic regression models examined interactions between maternal origin and SES. Results Syrian births increased exponentially between 2011 and 2013, along with the group’s forced migration into Lebanon. Although Syrian mothers are more socioeconomically disadvantaged compared with Lebanese mothers, Syrian LBW (6.2%) was only marginally higher than Lebanese LBW (5.6%; P = 0.059). Only 20–24-years-old Syrian women [odds ratio (OR) = 2.02 (0.98–4.16)] and those with ≥ university education [OR = 1.70 (1.22–2.36)] exhibited higher odds of delivering an LBW baby compared with Lebanese women of the same age and education. Conclusions The findings do not provide strong evidence for the epidemiological paradox in a forced migration context. However, the relatively advantageous LBW profile among Syrian neonates, despite their mothers’ low SES and exposure to acute and chronic psychological stress, points to protective mechanisms. One of these mechanisms may be a collective response by the displaced population to improve neonatal outcomes as a way of recovering from loss and death.
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