Frailty status is related to general and abdominal obesity in older adults

Abstract

The association between frailty and obesity may differ according to the heterogeneity of body mass index (BMI) and waist circumference (WC) phenotypes in older adults. We hypothesized that the use of simple indicators of general and abdominal obesity combined, may more accurately represent obesity and allow to further elucidate on how frailty status and its criteria are related to obesity. A sample of 1444 older adults, aged ≥65 years (Nutrition UP 65 study) was included in a cross-sectional analysis. General and abdominal obesity were defined according to World Health Organization BMI and WC cut-offs, and frailty by Fried et al. phenotype. A cluster analysis defined groups according to BMI and WC levels. Overweight (BMI between 25.0 and 29.9 kg/m²; 44.6%), general obesity (BMI ≥30.0 kg/m²; 39.0%), and abdominal obesity (WC >102 cm for men and >88 cm for women) were highly frequent (66.5%). Prefrailty (odds ratio [OR]: 2.33; 95% confidence interval [CI]: 1.52-3.57) and frailty (OR: 2.87; 95% CI: 1.58-5.22) were directly associated with the “general and abdominal obesity” cluster. Regarding frailty criteria, low handgrip strength (OR: 2.29; 95% CI: 1.55-3.38) and weight loss (OR: 0.27; 95% CI: 0.14-0.52) were also associated with this cluster. In this sample of older adults presenting a high frequency of overweight and obesity, prefrailty and frailty are linked to higher levels of adiposity, but only when both general and abdominal obesity are present. Present results emphasize the importance of the evaluation of both BMI and WC in the geriatric clinical practice and suggest that older adults presenting both general and abdominal obesity should be routinely screened for frailty.

Introduction

Obesity is considered one of the world's most problematic public health issues [1]. While body mass index (BMI) is the most widely used tool to estimate adiposity levels, the optimal level of adiposity in older adults is still a matter of discussion. Since aging is associated with considerable changes in body composition and fat distribution [2,3], waist circumference (WC), as an indicator of regional distribution of fat, has had an important role in the determination of health risks resulting from excess adiposity in older adults [3].

Research has been focused on the association of surrogate adiposity indicators with different outcomes. A higher risk of mortality in older adults with BMI <23 kg/m² and >33 kg/m² was observed in a meta-analysis [4]. Interestingly, increased mortality risk for high WC values was found across all BMI categories in other meta-analysis [5]. Furthermore, it was observed that older Americans presenting a BMI <18.5 kg/m² or >30 kg/m² at baseline were significantly more likely to experience disability during the follow-up period [6].

Frailty is a state of increased vulnerability to several adverse health outcomes with major implications for clinical practice and public health [7], [8], [9], but studies on the association between frailty and obesity have produced controversial results. A systematic review of longitudinal studies revealed a direct association between obesity and the incidence of frailty [10]. However, in frail community-dwelling older women, another study showed that those who were overweight or obese had reduced risk of clinical adverse events [11]. In fact, a U-shape relationship between frailty and BMI was also reported, with the lowest prevalence of frailty observed in individuals with a BMI between 25 and 29.9 kg/m² [12,13].

Obesity may exacerbate the age-related decline in health and physical function, resulting in a deterioration of overall health and quality of life [14]. Interestingly, the presence of obesity in frail older adults significantly contributed to a higher mortality rate [15], with both high BMI and WC being suggested as risk factors for frailty [16]. In a study that included Chinese older adults, it was found that WC was a better predictor of frailty than BMI [17].

The link between frailty and excess adiposity levels in older adults has been described in the literature, however, it merits further investigation. Despite BMI often being considered unsuitable for older adults, the use of sophisticated technologies that accurately measure body fat mass is not readily available in most clinical settings [2]. Therefore, it is important to explore the link between frailty and anthropometric measures, such as BMI and WC, which are easily assessed in clinical practice. Understanding this issue is relevant for developing strategies to target individuals with different levels of adiposity regarding their frailty status and to improve overall health and quality of life at an older age.

The described association between frailty and obesity may differ according to the heterogeneity of BMI and WC phenotypes. We hypothesized that the use of simple anthropometric measures of general and abdominal obesity combined, may more accurately represent obesity in older adults and allow to further elucidate on how frailty status and its criteria are related to obesity. Therefore, this study aims to explore the association between frailty status and indicators of body adiposity, such as BMI and WC. Moreover, the link between each frailty criterion, and these indicators will also be studied.