Association of weekend admission on immediate postoperative outcomes following non-elective cardiac operations

Background The "weekend effect" refers to inferior outcomes among patients admitted during weekends. Although documented across multiple medical specialties, studies evaluating weekend admission for cardiac surgery have yielded conflicting results. We assessed immediate postoperative outcomes following weekend cardiac admissions using a contemporary national database. Methods Adults (≥18 years) undergoing non-elective major cardiac operations, including coronary artery bypass grafting, valvular, and aortic procedures, were identified from the 2016–2022 National Inpatient Sample. Patients were stratified by weekend versus weekday admission, defined as operative intervention within a day of admission. The primary outcome was in-hospital mortality. Secondary outcomes included length of stay (LOS), hospitalization costs, and non-home discharge. Multivariable regression models adjusted for demographics, comorbidity burden, operative type, hospital volume, and year. Results Among an estimated 99,865 patients, 14,565 were admitted over the weekend. Compared to others, weekend patients were younger, more commonly female, and were more frequently insured by Medicaid (all p < 0.001). Following risk adjustment, weekend admission was associated with higher odds of in-hospital mortality (AOR 1.37, 95% CI 1.18–1.60), increased hospitalization costs (β +$5,831), and prolonged LOS (β +0.86 days, all p < 0.001). Mortality risk was attenuated at higher-volume centers. Conclusion Weekend admission for non-elective major cardiac surgery is associated with worse clinical outcomes and increased resource utilization nationwide, highlighting a persistent weekend care disparity which warrants further investigation into underlying drivers.