The Impact of Out-of-Hours Liver Transplantation on Outcomes: A Swedish National Study.

OBJECTIVES: This national, multicenter retrospective study of 764 adult liver transplantations (LT) in Sweden (2019-2023) employed a data-driven approach to identify the out-of-hours (OOH) high-risk window and evaluate its impact on patient outcomes and health care costs. SUMMARY BACKGROUND DATA: LT logistics often necessitate OOH surgery, but the evidence for an impact on outcomes remains conflicting, partly due to arbitrary window definitions. METHODS: Using the mathematical principle of permutations and linear regression analysis of 1-hour start-time intervals across 552 temporal windows, we identified the period with the greatest impact on the primary endpoint: the 3-month Comprehensive Complication Index (CCI). Secondary outcomes included intensive care unit length of stay, Clavien-Dindo complications, reoperations, patient and graft survival, and health care costs. RESULTS: The 17:00 to 05:59 window was identified as having the greatest negative impact on CCI. After adjusting for covariates, procedures initiated during this timeframe were associated with significantly higher CCI (β=7.41, 95% CI: 4.27-10.56, P<0.01), increased Clavien-Dindo IIIb and IV complications, 1.16 days longer intensive care unit stay and a higher risk of LT-related reoperations (odds ratio: 1.61, 95% CI: 1.11-2.36). One-year graft and patient survival were comparable between groups. Health care costs were 169.629 SEK (€15,500) higher per patient operated OOH, during the 3-month follow-up. CONCLUSION: This data-driven analysis identified a high-risk OOH window beginning earlier than previously reported (17:00 vs. traditional nighttime definitions). LT starting in this interval is associated with significantly increased morbidity and health care costs. Further studies are needed to evaluate mitigating strategies to enable daytime transplantation.