Investigator Gender Influence on Female Enrollment in Multicenter Vascular Trials: A Site-Level Analysis

This study aimed to determine whether the proportion of female patients enrolled at individual clinical trial sites differed according to site principal investigator (PI) gender in industry-sponsored multicenter vascular trials.

A retrospective, secondary, site-level analysis of seven completed Penumbra, Inc. (Alameda, CA, USA)-sponsored trials across neurovascular, peripheral, and coronary interventions was conducted. Sites were categorized as led by a female PI, a male PI with ≥1 female sub-investigator, or a male PI with no female investigators. Nonparametric tests, linear regression with trial-level fixed effects, and resampling-based sensitivity analyses were used to assess the association between PI gender and female enrollment. Given the small number of female-led sites, all findings were treated as exploratory.

Across 230 sites (N = 3114 patients), trial-level female enrollment ranged from 23.8% to 72.5%. Female site PIs were rare, representing approximately 3% of all site PIs. Female-led sites (n = 7) enrolled a higher proportion of female patients than male-led sites (median 73.9% [interquartile range (IQR) 64.1-77.5] versus 51.2% [IQR 33.3-69.0], p = 0.03). In adjusted regression analysis, female PI sites enrolled an average of +15.7 percentage points more women (95% bootstrap CI, +7.1 to +23.4; permutation p = 0.074). The presence of female sub-investigators alone was not associated with higher female enrollment (50.0% versus 52.2%, p = 0.606).

Sites led by female PIs enrolled a higher proportion of female patients in vascular clinical trials than sites led by male PIs. Although causality cannot be inferred, these exploratory findings suggest that increasing female representation in site PI leadership may be one actionable strategy to improve enrollment representativeness in vascular clinical trials.