Off-hour admission and mortality in acute type A aortic dissection: A nationwide cohort of 25,608 surgically treated cases: Secondary data analysis of German hospital episode statistics from 2010 to 2023.

Objectives: Whether admission timing influences outcomes after surgery for acute Stanford type A aortic dissection (TAAD) remains uncertain. This study examined the association between off-hour admission and in-hospital mortality in a nationwide cohort, including seasonal, weekday, and time-of-day variation. Methods: All surgically or hybrid-treated TAAD cases were identified in the German Diagnosis Related Groups database from 2010 to 2023. Multilevel logistic regression was used to evaluate factors associated with in-hospital mortality, adjusting for age, sex, comorbidity burden (Elixhauser score), annual hospital volume, and temporal variables (season, weekday, and time of admission). Results: Among 25,608 patients (median age 65 years; 62.4% male), overall in-hospital mortality was 19.0%. Mortality showed no seasonal variation after adjustment. In contrast, significant off-hour effects were observed. Weekend admissions were associated with greater mortality compared with Monday (Saturday: adjusted odds ratio [aOR], 1.20; 95% CI ,1.05-1.36; Conclusions: Seasonal patterns are not related with outcomes, but weekend and nighttime admissions were independently associated with increased in-hospital mortality after TAAD repair, adding further population-level evidence to an ongoing debate. These findings support centralized 24/7 aortic emergency care, consistent team availability, and optimized regional transfer pathways to mitigate temporal disparities and improve survival.