OBJECTIVE: The elderly (defined by an age of ≥65 years) are underrepresented in rheumatology trials, possibly due to investigator's concerns of increased premature discontinuations in higher age groups. We evaluated whether the proportion of included elderly individuals (PE) is independently associated with participant retention in rheumatology trials.
METHODS: MEDLINE was searched for randomized controlled trials (RCTs) in rheumatoid arthritis (RA) and osteoarthritis (OA) on any intervention (years 2016 and 2017). PE was either extracted from the research manuscript or estimated from an assumed (truncated) normal distribution. Mixed effects meta-regression models including several covariates assessed whether there is an independent association between PE and participant retention. Sensitivity analyses evaluated whether associations were connected to attrition due to lack of efficacy (LoE) or adverse events (AE).
RESULTS: 243 RCTs comprising over 48,000 participants were included. Pooled participant retention was 88%. PE was not associated with retention in the unadjusted (p = 0.97) or adjusted (all: p ≥ 0.14) models. Of all covariates, only study duration and type of intervention were associated with retention (both: p < 0.001). Post hoc analyses allowing for interaction revealed a small but statistically significant positive association between PE and retention in pharmacological and a negative association in physical/physiotherapeutic (overall p for interaction = 0.05) interventions. No associations were found for PE and attrition due to LoE or AE.
CONCLUSION: Participant retention in RA and OA trials is high and not associated with PE. These findings should stimulate investigators to include more elderly people in rheumatology trials. This article is protected by copyright. All rights reserved.