Ethnicity in Rheumatoid Arthritis Trials Not Reflective of Disease Burden

US demographics
US demographics
Researchers confront racial and ethnic disparity for minorities in RA randomized controlled trials.

Despite the high burden of rheumatoid arthritis (RA) in racial and ethnic minority groups, these groups are considerably underrepresented in RA randomized controlled trials, according to research published in JAMA Network Open. Researchers also indicated that randomized clinical trial (RCT) enrollment numbers were not reflective of the national prevalence of RA among men and the elderly, largely due to exclusion criteria.

Researchers conducted a large-scale analysis of the demographic and diversity characteristics of RA RCTs conducted between January 2008 and January 2018 to evaluate whether racial and ethnic minority groups, women, and elderly people were adequately represented.

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Researchers identified 240 RCTs inclusive of 77,701 participants. Of these, 52.5% of the trials (n=126) were conducted at a US-based site; among these, 94.4% were industry funded, 78.6% enrolled 200 or more participants, and 94.4% were focused on a biologic or synthetic disease-modifying antirheumatic drug. No statistically significant difference was noted in the percentage of trials within this subgroup that reported race or ethnicity, compared with the total sample (64.3% vs 54.2%). A total of 35.7% of trials did not report on race or ethnicity.

White participants were, by and large, the most represented group (ranging from 74.6% in 2010 to 97% in 2013). Over the 10-year review period, black patients were represented in 0.6% of trials in 2013 and 4.7% in 2012, whereas Hispanic representation fell from 14.4% in 2010 to 0% in 2014. Asian, Native Hawaiian, Pacific Islander, American Indian, and Alaska Native representation was also low.

In terms of sex, 96.3% of trials included both men and women. Over 10 years, the enrollment of men ranged from 17.3% to 27.3%, with no significant trend in the enrollment of men vs women over time. Investigators found that the representation of men in RCTs was “significantly lower” than the burden of men with RA nationally (20.4% vs 28.6%).

To assess the inclusion of elderly populations, researchers reviewed 99 RCTs and found that, most frequently, trials excluded adults older than 74 or 75 years of age (17.9% of trials). RCTs with at least 1 US-based site had a lower proportion of trials with an upper age limit compared with all included trials. Mean participant age across the 80.4% of trials that reported age was 52.6±11.4 years.

Study limitations include potential biases by excluding RCTs that did not report race or ethnicity information and the inclusion of only trials that focused on systemic, disease-modifying therapies compared with other types of estimates.

“Despite national efforts to increase diversity in [randomized controlled trial] participation, there was no trend toward improved representation of racial/ethnic minority groups … between 2008 and 2018,” the researchers concluded. “This review also found that the enrollment of men in RA [randomized controlled trials] … was significantly lower than the prevalence of RA in men nationally, and that elderly people were often excluded from RA [randomized controlled trials].”

They added, “Given the disproportionate burden of RA among racial/ethnic minority groups, it is imperative that policy makers better incentivize the inclusion of racial/ethnic minority populations in RA randomized controlled trials.”

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Strait A, Castillo F, Choden S, et al. Demographic characteristics of participants in rheumatoid arthritis randomized clinical trials. A systematic review. JAMA Netw Open. 2019;2(11):e1914745.