The role of recipient sex in the post-liver transplant prognosis of acute-on-chronic liver failure.

Background & aims: Limited data exists on the impact of recipient sex on the post-liver transplant (LT) outcomes in patients with acute-on-chronic liver failure (ACLF). This study aims to utilize a national transplant registry to evaluate the relationship between recipient sex and post-transplant outcomes, stratified by ACLF severity. Methods: The United Network for Organ Sharing Standard Transplant Analysis and Research (UNOS-STAR) database was queried to collect health information on 47,447 patients who underwent liver transplantation between 1987 and 2019. The cohort was stratified by biological sex, and further subdivided into groups based on ACLF severity: Grade 0 (without ACLF) and Grade 1-3 in increasing severity. The primary outcomes assessed were all-cause mortality and graft failure while secondary outcomes included specific causes of death. Results: No sex-based disparities were observed in the primary outcomes of all-cause mortality and graft failure across all grades of ACLF. However, females without ACLF exhibited a higher risk of mortality from recurrent graft disease compared to males. Time-point analyses revealed higher 180-day and 360-day mortality rates in females without ACLF. Among patients with ACLF Grade 1, females demonstrated higher 30-day mortality, but no significant differences were found at 90-, 180- or 360-days. Among patients with ACLF Grades 2 and 3, however, no sex-based differences in 30-day to 360-day mortality were identified. Conclusion: Factors other than sex appear to play a more critical role in determining the long-term transplant outcomes in ACLF. The increased short-term mortality observed in females with ACLF grade 1 warrants further investigation to elucidate potential contributing factors.