Enrollment of Historically Underrepresented Groups in Peripheral Arterial Disease Trials: A Systematic Review

Older adults, women, and members of underrepresented racial and ethnic groups are substantially underrepresented in cardiovascular clinical trials. This limits the generalizability of trials' findings, access to new treatments, and trust in medical research. Here, we report the state of representativeness in lower extremity peripheral arterial disease (PAD) trials.

All clinical trials published between 2000 and 2023 studying treatments for lower extremity PAD that enrolled ≥100 patients with at least some patients in North America were included. Temporal trends regarding representation of older adults, women, and members of underrepresented racial and ethnic groups were identified.

A total of 110 trials enrolling 57,451 patients were identified. Of these trials, 78 (71%) were randomized controlled trials, 88 (80%) received industry funding, 24 (22%) received government funding, and 66 (60%) enrolled in North America only. Overall, the weighted mean age was 66.8 ± 2.1 years, and 28% of trial patients were women. In terms of race, 0.03% of participants were American Indian/Alaska Natives, 2.4% were Asian, 5.0% were Black or African American, and 0.01% were Native Hawaiian or Pacific Islanders. Of the trial participants, 1.3% were Hispanic. Among all trials, there were significant increases in mean age and proportion of women but not of non-White patients over time. Among government-funded North American trials, there were significant increases in proportions of women and non-White patients (driven by enrollment of Black patients) over time.

Underenrollment of older adults, women, and members of historically underrepresented ethnic/racial groups continues to improve but remains a significant problem in clinical trials evaluating therapies for lower extremity PAD.