Objective: To assess how and to what extent socioeconomic status and ethnicity/race of participants are reported in randomized controlled trials (RCTs) on systemic sclerosis (SSc), and to estimate the representativeness of different ethnic/racial groups in SSc RCTs.

Methods: We searched all published RCTs on SSc indexed in PubMed. We retrieved information on main features of RCTs published from 2000 onward and recorded for each study whether race/ethnicity was reported; how ethnicity/race was defined and assigned; and the number of patients included for each racial/ethnic group. Multivariable logistic regression was used to identify factors associated with race/ethnicity reporting. Proportion of races/ethnicities included in US-based RCTs on SSc was examined and compared with US demographic data.

Results: We included 106 studies, mostly conducted in Europe (42%) or North America (25%), published after 2010 (74%), and enrolling a total of 6,693 patients. About one-third of studies provided information about race/ethnicity, with no improved reporting over time. Only 2 papers reported patient's socioeconomic status. Study location (US or intercontinental) was the only significant factor associated with a better reporting of race/ethnicity in multivariable analysis. In studies where race/ethnicity was reported, White patients were mostly represented (79%), followed by Asian (7%), and African American (6%). In the sensitivity analysis limited to studies from the US, underrepresentation of African American patients was observed in the 2000-2010 time period, but not later.

Conclusion: Documentation of race/ethnicity and socioeconomic status is poor in RCTs on SSc. More effort should be made to document race/ethnicity and socioeconomic status and to promote diversity in SSc RCTs.