Background

In the context of co-morbid illness and increasing age, data on excess morbidity from pertussis in older adults is crucial for immunisation policy but has been largely limited to case-series.

Methods

We designed a matched case-control study nested within a population-based cohort of 267,153 adults aged ≥45 years in New South Wales, Australia (The 45 and Up Study cohort). Excess hospital bed days, emergency department (ED) admissions, general practitioner (GP) visits, and prescriptions were estimated using negative binomial regression models. An additional self-controlled analysis was also conducted to validate the main models, and to evaluate results for those with either asthma or a body mass index (BMI)$\ge$30 compared to those without these risk factors.

Results

Based on 524 pairs of PCR-confirmed pertussis cases and matched controls, we estimated an excess healthcare utilisation per case of 2.5 prescriptions (95% CI: 0.2–4.7), of which 1.1 (95% CI: 0.5–2.2) were antibiotics, 2.3 GP visits (95% CI: 2.0–2.6), and 0.1 ED admissions (95% CI: 0.1–0.2). Compared to those 45–64 years, cases ≥65 years had a significantly greater excess for all prescriptions (1.1 vs 4.7/case), antibiotic prescriptions (0.1 vs 2.2/case), and ED admissions (0.1 vs 0.2/case), but no significant excess of respiratory-related hospital bed days. An additional self-controlled analysis confirmed that cases with either asthma or BMI$\ge$30 had higher overall healthcare utilisation but this was not associated with pertussis infection.

Conclusion

We found a substantial excess outpatient healthcare burden among adults aged 65 years and over with PCR-confirmed pertussis, supporting further evaluation of preventive measures.

中文翻译：

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65岁及以上的澳大利亚成年人因百日咳而导致的医疗资源利用率高

背景

在合并症和年龄增长的背景下，老年人因百日咳而引起的额外发病率数据对免疫政策至关重要，但在很大程度上仅限于病例系列。

方法

我们设计了一个匹配的病例对照研究，该研究嵌套在澳大利亚新南威尔士州以人群为基础的267 153名≥45岁的成年人队列中（45岁及以上研究队列）。使用负二项式回归模型估算了多余的病床天数，急诊室（ED）入院，全科医生（GP）访视和处方。还进行了另一项自控分析，以验证主要模型并评估患有哮喘或体重指数（BMI）的结果$\ge$与没有这些危险因素的人相比，则为30。

结果

根据524对经PCR确诊的百日咳病例和相匹配的对照组，我们估计每例病例有2.5处方（95％CI：0.2–4.7），其中1.1（95％CI：0.5–2.2）是抗生素，导致医疗过度使用； 2.3 GP访视（95％CI：2.0-2.6）和0.1 ED入院率（95％CI：0.1-0.2）。与45-64岁相比，≥65岁的病例在所有处方（1.1比4.7 /例），抗生素处方（0.1比2.2 /例）和ED入院（0.1比0.2 /例）中都有明显更多的过量，但呼吸相关的医院病床天数没有明显增加。另一项自我控制分析证实，患有哮喘或BMI的患者$\ge$30例总体医疗保健利用率较高，但这与百日咳感染无关。

结论

我们发现在65岁及以上的成年人中，经PCR确诊的百日咳有相当大的门诊医疗负担，支持进一步评估预防措施。