Prevalence and Characteristics of Interventional Trials Conducted Exclusively in Elderly Persons: A Cross-Sectional Analysis of Registered Clinical Trials

Background
Elderly patients represent the greatest consumers of healthcare per capita but have historically been underrepresented in clinical trials. It is unknown how many trials are designed to focus exclusively on elderly patients.
Objective
To define the prevalence of interventional trials that study exclusively elderly persons and describe the characteristics of these trials, including their distribution across conditions most prevalent in the elderly.
Design
All interventional clinical trials enrolling exclusively elderly patients (≥65 years), conducted primarily in high-income countries, and initiated between 2006 and 2014, identified through ClincialTrials.gov.
Main Measures
Trials were identified and characterized according to design features and disease categories studied. Across disease categories we examined the burden of disease in the elderly in high-income countries (measured in disability-adjusted life years [DALYs]) and compared to the number of trials conducted exclusively in the elderly.
Results
Among 80,965 interventional trials, 1,112 (1.4%) focused on elderly patients. Diverse types of interventions were studied in these trials (medications 33%, behavioral interventions 18%, and dietary supplements 10%) and the majority was funded by non-profit organizations (81%). Studies tended to be small (median sample size 122 participants [IQR 58, 305]), single-center studies (67%). Only 43% of 126 disease categories affecting elderly persons were studied in trials focused on the elderly. Among these disease categories, there was a 5162-fold range in the ratio of DALYs per trial. Across 5 conditions where over 80% of DALYs are in the elderly, there were a total of only 117 trials done exclusively in the elderly.
Conclusions
Very few and mostly small studies are conducted exclusively in elderly persons, even for conditions that affect almost exclusively the elderly.

背景
老年患者是人均医疗保健消费最高的群体，但历来在临床试验中的代表性严重不足。目前尚不明确有多少项试验专门以老年患者为研究焦点。

研究目的
本研究旨在明确专门针对老年人群的干预性临床试验的患病率，并描述此类试验的特征，包括其在老年人群高发疾病中的分布情况。

研究设计
通过ClinicalTrials.gov数据库检索得到的所有仅纳入≥65岁老年患者、主要在高收入国家开展、且于2006年至2014年间启动的干预性临床试验。

主要测量指标
根据试验设计特征与所研究的疾病类别对试验进行识别与特征描述。在各疾病类别中，我们分析了高收入国家老年人群的疾病负担（以伤残调整寿命年（disability-adjusted life years, DALYs）衡量），并与专门针对老年人群开展的试验数量进行对比。

研究结果
在80965项干预性临床试验中，有1112项（1.4%）以老年患者为核心研究对象。此类试验涵盖多种干预类型：药物治疗占33%、行为干预占18%、膳食补充剂占10%，且绝大多数由非营利组织资助（81%）。试验规模普遍偏小（中位样本量为122名受试者，四分位间距（Interquartile Range, IQR）为58~305），且多为单中心试验（67%）。在影响老年人群的126种疾病类别中，仅有43%的类别被纳入专门针对老年人群的试验研究。在这些疾病类别中，每例试验对应的DALYs比值差异可达5162倍。在5种老年人群贡献超过80%疾病负担的疾病中，专门针对老年人群开展的试验总计仅117项。

研究结论
即便对于几乎仅影响老年人群的疾病，专门以老年患者为对象开展的试验也极为稀少，且大多规模较小。