Representation of Older Adult Patients in Clinical Trials

Abstract

Older adults remain significantly underrepresented in clinical trials. This is concerning because age-associated physiological changes can alter drug pharmacokinetics and pharmacodynamics. This paper examines the status of older adult representation in clinical trials, analyzes contributing factors, and discusses initiatives to address gaps. Data were collected from studies completed between 2010 and 2025 using ClinicalTrials.gov to assess age-related inclusion/exclusion criteria. Further, two surveys of pharmaceutical companies were initially conducted to assess age ranges of randomized patients in pivotal trials, what clinical pharmacology approaches were applied to potentially support dosing in older adult patients, whether exclusion criteria disproportionally excluded older patients, reasons older adult patients were not randomized, and whether older patients more often discontinued trials prematurely. Exclusion criterion based on an age cut-off was rarely applied. Pharmacokinetic analyses were performed for most trials, but only one age-related dosing recommendation was reported out of 29 products. In a survey of 41 clinical studies, exclusion criteria showed no bias toward exclusion of patients > 80 years. Reasons for not randomizing older patients were diverse and trial dependent. Subjective reasons for non-randomization at higher frequencies in older patients were patient wish and doctor advice. Discontinuation rate did not reveal a clear age-related trend. When comparing trial age composition to disease prevalence by age, a mismatch was evident with fewer than expected older patients enrolled. This research identifies the gap between trial participation and disease prevalence by age groups, offering insights for sponsor companies to enhance older adults' inclusion in clinical research.