Sex Disparity in Extracorporeal Membrane Oxygenation Clinical Trial Enrollment.

Objectives: Multiple studies have shown that extracorporeal membrane oxygenation (ECMO) is used clinically more often in men than women. Because clinical trials provide the basis for identifying patients who are likely to benefit from medical therapies, we hypothesized that sex-based imbalances in ECMO trial enrollment may both reflect and perpetuate these observed disparities. Our objective was to determine whether sex-based enrollment imbalances exist within the published ECMO clinical trial literature.

Design: Cross-sectional analysis.

Setting: Randomized controlled trials published between 2003 and 2023 that either tested ECMO as a treatment modality or tested another intervention among patients receiving ECMO.

Patients: Not applicable.

Interventions: None.

Measurements And Main Results: We used the Cochrane Highly Sensitive Search Strategy to search PubMed for eligible trials. Data on participant demographics, trial characteristics, and journal information were abstracted for each publication. The primary outcome of interest was the proportion of male and female participants in each published trial. The initial literature search identified 774 articles. Of these, 31 were eligible for inclusion, and 28 provided data on the sex of study participants. Twenty-six of these 28 trials (93%) enrolled more men than women, and in aggregate women comprised 28% (95% CI, 26-30%) of all trial participants (551/1956 subjects). Trials involving extracorporeal cardiopulmonary resuscitation (ECPR) exhibited the largest sex-based enrollment differences (83% men) followed by venoarterial ECMO for cardiogenic shock (73% men). Among trials published in journals with impact factors of ten or higher 74% (95% CI, 72-76%) of participants were men. Only two trials (7%) provided data on the race or ethnicity of study participants.

Conclusions: Substantial sex-based disparity exists in published ECMO clinical trials. Underrepresentation of women relative to disease prevalence is most significant among trials utilizing venoarterial ECMO for cardiogenic shock and ECPR for cardiac arrest, limiting the applicability of findings from these trials for women.