The weekend effect in internal medicine admissions: A limited impact at a large tertiary-care center

Background: This study was conducted to examine whether a “weekend effect” exists in internal medicine departments of a large tertiary medical center in Israel. Methods: We conducted a retrospective cohort study of patients > 18 admitted to internal medicine wards at Tel Aviv Sourasky Medical center from 2015 to 2023. Admissions were classified as weekday (Sunday-Thursday) or weekend (Friday-Saturday) based on admission day. The primary outcome was in-hospital mortality. Multivariable logistic regression models were used to adjust for age, sex, and comorbidity burden. Subgroup analyses were performed by diagnostic category. Results: A total of 155,713 admissions were examined, out of which 35,512 (22.8%) occurred on weekends and 120,201 (77.2%) on weekdays. Weekend admissions were associated with a small increase in unadjusted risk of mortality (8.5% versus 8%, P = 0.003). However, after adjustment for covariates the association diminished and did not reach statistical significance (aOR 1.03 CI 0.99-1.08, P = .1). The only diagnosis group with higher weekend-associated mortality was the hematologic/oncologic group (aOR 1.42, 95% CI 1.07-1.82; P = .005), driven predominantly by patients presenting with severe thrombocytopenia. Conclusions: In a well-resourced tertiary-care setting in Israel, weekend admission to internal medicine wards was not independently associated with short-term mortality. However, diagnostic subgroup analyses suggest certain patient populations may remain at increased risk during weekend admissions.