Race and ethnicity in the landmark hypertrophic cardiomyopathy trials: representation against population, site-catchment, and disease-referenced expectations

BACKGROUND: Hypertrophic cardiomyopathy (HCM) is a pan-ethnic disease, at least as common in Black as in White Americans, yet Black patients reach specialist care later, undergo septal reduction less often, and die sooner. Whether the defining trials enrolled representatively is unknown. We sought to measure Black participation in the landmark HCM trials against three expectations of increasing stringency, and to test whether trial site geography or quantitative eligibility thresholds account for the shortfall. METHODS: Of 197 registered interventional HCM trials, 32 met prespecified landmark tiers; demographics were extracted for 16 and 13 reported race. The Black share of Black plus White participants was pooled by random-effects meta-analysis and compared with the US adult population, with each trial?s own site counties, and with a disease-referenced echocardiographic expectation. Site geography and eligibility thresholds were tested using site addresses, census data, and NHANES. RESULTS: Across 13 trials, 70 of 1,780 Black or White participants were Black. The pooled Black share was 3.98% (95% CI 2.68-5.86), against a population expectation of 16.5%, giving a participation-to-prevalence ratio (PPR) of 0.24 (95% CI 0.16-0.36), the lowest of any racial and/or ethnic minority group. The clinical trial site network reached 63.7% of Black and 47.5% of White US adults, with geospatial analysis predicting 26.4% Black enrollment; however, every trial fell below this expectation. Quantitative eligibility thresholds closed only 2.0% of the enrollment gap. CONCLUSIONS: Black participation was about one quarter of the population expectation. Neither site geography nor eligibility thresholds explain it.