The Weekend Effect: Is Surgery on Friday Associated With a Greater Risk of Complications?

INTRODUCTION: Health-care systems routinely adjust operational workflows to accommodate changing demands throughout the week. In turn, quality of inpatient care may differ between weekends and weekdays. The objective of the current study was to characterize the association between the weekend effect and postoperative outcomes among patients undergoing a major surgical procedure. METHODS: Patients who underwent a major surgical procedure between 2016 and 2021 were identified from the Medicare database. Major surgery was defined as coronary artery bypass grafting, abdominal aortic aneurysm repair, pneumonectomy, pancreatectomy, and colectomy. Multivariable models were used to compare textbook outcome (TO) among patients who underwent surgery 1 day before (preweekend) versus 1 day after the weekend (postweekend). RESULTS: Among 232,504 Medicare beneficiaries, 101,568 (43.7%) underwent preweekend surgery. Patients who underwent preweekend surgery were less likely to achieve a TO (preweekend: 44.9% vs postweekend: 49.4%; P < 0.001). Notably, preweekend surgery was associated with higher rates of intensive care unit utilization (preweekend: 55.2% vs postweekend: 53.1%), complications (preweekend: 37.1% vs postweekend: 33.1%), readmission (preweekend: 23.0% vs postweekend: 22.2%), and mortality (preweekend: 9.6% vs postweekend: 8.8%) (all P < 0.001). On multivariable analysis, preweekend surgery was associated with 7% lower odds of TO (odds ratio 0.93; 95% confidence interval 0.92-0.95). CONCLUSIONS: Operational changes in hospitals over the weekend may introduce vulnerabilities in the delivery of surgical care. Patients undergoing preweekend surgery experienced worse surgical outcomes and were less likely to achieve TO across diverse procedures and hospital types.