Outcome domains measured in randomized controlled trials of physical activity for older adults: a rapid review

Toward development of a core outcome set for randomized controlled trials (RCTs) of physical activity (PA) interventions for older adults, the purpose of this study was to identify outcome domains and subdomains ('what' was measured) in previously published RCTs of PA for older adults.

We conducted a rapid review and searched Ovid MEDLINE for recently- published (2015-2021), English-language, RCTs of PA interventions for older adults (mean age 60+ yrs). We limited to articles published in Web of Science top-10 journals in general and internal medicine, geriatrics and gerontology, rehabilitation, and sports science. Two reviewers independently completed eligibility screening; two other reviewers abstracted trial descriptors and study outcomes. We classified study outcomes according to the standard outcome classification taxonomy endorsed by the Core Outcome Measures in Effectiveness Trials Initiative.

Our search yielded 548 articles; 67 articles were eligible to be included. Of these, 82% were efficacy/effectiveness trials, 85% included both male and female participants, and 84% recruited community-dwelling older adults. Forty percent of articles reported on interventions that involved a combination of group and individual PAs, and 60% involved a combination of PA modes (e.g., aerobic, resistance). Trial sample size ranged from 14 to 2157 participants, with median (IQR) of 94 (57-517); 28,649 participants were included across all trials. We identified 21 unique outcome domains, spanning 4/5 possible core areas (physiological/clinical; life impact; resource use; adverse events). The five most commonly reported outcome domains were physical functioning (included in n=51 articles), musculoskeletal and connective tissue (n=30), general (n=26), cognitive functioning (n=16), and emotional functioning/wellbeing (n=14). Under these five outcome domains, we further identified 10 unique outcome subdomains (e.g., fall-related; body composition; quality of life). No outcome domains or subdomains were reported consistently in all RCTs.

We found extensive variability in outcome domains and subdomains used in RCTs of PA for older adults, reflecting the broad range of potential health benefits derived from PA and also investigator interest to monitor a range of safety parameters related to adverse events. This study will inform development of a core outcome set to improve outcome reporting consistency and evidence quality.