Abstract Body (Do not enter title and authors here): Background:
Sex-based disparities in heart failure and transplant outcomes are increasingly recognized. Although women represent a minority of heart transplant recipients, conflicting data exist on whether recipient sex impacts survival and rejection. We conducted a meta-analysis to assess the impact of recipient sex on post-transplant mortality and rejection outcomes.
Methods:
We systematically searched PubMed, Embase, and Scopus through February 2025, in accordance with PRISMA guidelines. Eligible observational cohort studies comparing male and female heart transplant recipients and reporting outcomes of mortality and/or rejection were included. Exclusion criteria included pediatric populations, second transplants, and non-original research. 16 studies involving 301,893 patients (228,493 male; 73,400 female) were included. Data extraction was independently performed by three reviewers; risk of bias was assessed using the Newcastle-Ottawa Scale. Statistical analyses were conducted using Review Manager (RevMan 5.4), with hazard ratios (HR) pooled using inverse variance random-effects models. Heterogeneity was evaluated with the I² statistic.
Results:
Meta-analysis of six studies evaluating post-transplant mortality showed no significant difference between male and female recipients (HR: 1.00 [95% CI: 0.88–1.15], p=0.96; I²=75%). Seven studies reported on rejection outcomes. Female recipients demonstrated no significant difference in rejection rates compared to males (HR: 0.99 [95% CI: 0.89–1.09], p=0.82; I²=53%). Across studies, baseline characteristics including age, comorbidities, and mechanical circulatory support usage were comparable. The overall quality of studies ranged from moderate to high.
Conclusion:
We found no statistically significant difference in post-transplant mortality or rejection rates between male and female heart transplant recipients. Despite moderate-to-high heterogeneity across studies, the direction and consistency of effect sizes support the conclusion that recipient sex alone does not independently affect major outcomes. These findings reinforce the importance of equitable candidate selection and highlight the need for future prospective studies exploring the biological and sociocultural mechanisms underlying outcome disparities.