This national, multicenter retrospective study examined whether the timing of liver transplantation (LT) start time influences postoperative outcomes and costs. LT logistics frequently necessitate procedures outside routine hours, but previous evidence on the impact of out-of-hours (OOH) surgery has been inconsistent, in part because many studies use arbitrary definitions of nighttime. To address this, the authors used a data-driven approach to identify an empiric high-risk OOH window and to quantify its association with morbidity, resource use and costs.
The study included 764 adult liver transplantations performed in Sweden from 2019 through 2023. The investigators applied the mathematical principle of permutations combined with linear regression to test 1-hour start-time intervals across 552 candidate temporal windows. The primary endpoint was the 3-month Comprehensive Complication Index (CCI), a continuous measure that captures cumulative postoperative morbidity. Secondary endpoints included intensive care unit (ICU) length of stay, Clavien-Dindo complication grades, reoperations related to LT, patient and graft survival, and health care costs during a 3-month follow-up.
The analytic strategy was designed to avoid predefining daytime versus nighttime and instead to identify the contiguous time interval with the strongest association with the primary endpoint.
Using the permutation and regression framework, the authors identified the 17:00 to 05:59 interval as the temporal window most strongly associated with worse early postoperative morbidity. After adjustment for covariates, LT procedures initiated during this 17:00–05:59 window were associated with a significantly higher 3-month CCI (β = 7.41; 95% CI: 4.27–10.56; P < 0.01). This finding indicates a measurable and statistically significant increase in aggregated complications when transplantation began in that empirically defined OOH period.
Compared with transplants started outside the identified OOH window, procedures begun between 17:00 and 05:59 had higher rates of serious complications categorized as Clavien-Dindo IIIb and IV. There was also an increased likelihood of liver-transplant–related reoperations, with an odds ratio of 1.61 (95% CI: 1.11–2.36). In addition, ICU length of stay was longer by 1.16 days on average for patients whose procedures started in the OOH window. Despite these increases in morbidity and resource use during the early postoperative period, one-year graft survival and patient survival were reported as comparable between OOH and non-OOH groups.
The investigators evaluated health care costs during the 3-month follow-up and found higher expenditures associated with OOH transplants. Specifically, costs were 169,629 Swedish kronor higher per patient operated during the 17:00–05:59 window, reported in the abstract with an equivalent of approximately €15,500. The reported increase in costs aligns with the observed increases in complication burden, reoperations and ICU utilization.
This study uses a reproducible, data-driven approach to define an empiric high-risk OOH period for liver transplantation and documents an association between LT start time within 17:00–05:59 and increased early morbidity, reoperation risk and short-term resource use and costs. Notably, the identified window begins earlier (17:00) than many conventional definitions of nighttime, suggesting that risk associated with off-hours LT may commence in the evening rather than at later night hours.
Clinical implications include consideration of operational strategies to reduce OOH transplantation when feasible or to implement targeted mitigation measures (staffing models, fatigue countermeasures, standardized protocols) for procedures that must occur during the higher-risk interval. The authors highlight the need for further studies to evaluate such mitigating strategies and to determine whether shifting more transplants to daytime hours reduces morbidity and costs without compromising access to organs.
The report summarized here is a retrospective, observational analysis and thus can demonstrate association but not definitive causation. The abstract does not provide full details about patient-level covariates, specific adjustments included in the multivariable models, or center-level factors; those details were not reported in the abstract. The authors state no conflicts of interest. Further peer-reviewed publication of the full data and analyses would be required to assess residual confounding, generalizability to other health systems, and the potential effects of specific mitigation policies.
In this national Swedish cohort of 764 adult liver transplantations (2019–2023), a data-driven analysis identified 17:00 to 05:59 as an out-of-hours window associated with a significantly higher 3-month Comprehensive Complication Index, increased serious Clavien-Dindo complications, higher reoperation rates, longer ICU stays and greater short-term health care costs. One-year graft and patient survival were similar between groups. The authors recommend further research to test strategies that could permit more daytime transplantation or otherwise mitigate the increased morbidity and costs observed when LT starts in the identified OOH interval.