Data published in Seminars in Arthritis and Rheumatism suggest that the elderly are underrepresented in randomized clinical trials in rheumatoid arthritis (RA) and osteoarthritis (OA), limiting the applicability of studied treatments in this population.

Investigators performed a systematic review of randomized controlled trials and population-based studies in RA and OA. The online MEDLINE database was searched for representative randomized controlled trials and population-based studies published between 2016 to 2017 and 2013 to 2017, respectively. Selected by 2 independent reviewers, studies were excluded if they did not report the mean or median age of participants at baseline. Random effects meta-analyses were conducted to estimate the pooled percentage of elderly people (≥65 years), the mean age of study participants, and the percentage of women stratified both by disease (RA and OA) and study type. Stratified estimates were subsequently compared in order to identify differences in representation between RA and OA research.

A total of 265 randomized controlled trials comprising 51,240 participants and 53 population-based studies comprising 523,630 participants were reviewed. In both RA and OA, randomized controlled trials included lower percentages of elderly people compared with population-based studies. Specifically, there were 18% (95% CI, −22 to −13) and 22% (95% CI, −30.0 to −9.0) fewer elderly participants in RA and OA trials, respectively. In addition, the mean patient age observed in randomized controlled trials was significantly lower than in population-based studies: RA, −5.2 years (95% CI, −6.8 to −3.5); OA, −4.7 years (95% CI, −7.5 to −2.0). Randomized controlled trials also had a smaller standard deviation in participant age: RA, −1.9 years (95% CI, −2.6 to −1.3); OA, −2.7 years (95% CI, −4.2 to −1.2). Each of these comparisons was found to be statistically significant (P ≤.001). The percentage of women included in both RA and OA studies was comparable across trial designs. The funding source did not appear to influence the underrepresentation of the elderly in randomized controlled trials. However, the type of intervention to which randomized control trial participants were assigned did appear to influence the deficit, although only in RA research (P =.02).

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These data suggest that intervention designs utilized in randomized controlled trials may not be typically applicable in the elderly population. Researchers described this as an “urgent” issue, given the high incidence of RA and OA in the elderly. Future research efforts should increase the percentage of elderly individuals in RA and OA clinical trials. In addition, age and sex should be studied as an outcome determinant, the researchers wrote.

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Palmowski A, Buttgereit T, Palmowski Y, et al. Applicability of trials in rheumatoid arthritis and osteoarthritis: A systematic review and meta-analysis of trial populations showing adequate proportion of women, but underrepresentation of elderly people [published online November 2, 2018]. Semin Arthritis Rheum. doi:10.1016/j.semarthrit.2018.10.017