Elective, major noncardiac surgery on the weekend: a population-based cohort study of 30-day mortality

Importance — Previous research has demonstrated that patients undergoing elective surgery on the weekend had an adjusted risk of 30-day mortality that was significantly higher than that of patients operated upon during the week. The generalizability of this association and effect size is unknown.

Objectives — The aim of this study was to investigate the generalizability of the association between elective weekend surgery and increased 30-day postoperative mortality.

Research Design — A retrospective, propensity score-matched cohort analysis of linked population-based health administrative data was carried out.

Subjects — Individuals undergoing elective, intermediate, intermediate-risk to high-risk all describe the noncardiac surgery exposure at all acute care hospitals in Ontario, Canada, between 2002 and 2012 were included.

Exposure — Elective surgery was performed on the weekends.

Measures — All-cause mortality was measured within 30 days of the operation.

Results — A total of 333,344 patients were studied, of whom 2826 died within 30 days of surgery (overall crude mortality rate 8.5 deaths per 1000). Weekend elective surgery was performed on 2520 patients, of whom 2518 were successfully propensity score matched to weekday surgical patients. Undergoing elective surgery on the weekend was associated with a 1.96 times higher odds of 30-day mortality than weekday surgery (95% confidence interval, 1.36-2.84) in a propensity-matched analysis. This significant increase in the odds of postoperative mortality was confirmed using a multivariable logistic regression analysis (odds ratio 1.51; 95% confidence interval, 1.19-1.92).

Conclusions — Similar to previous studies in distinct healthcare systems, patients in Ontario undergoing elective surgery on the weekend experienced an increased risk of 30-day postoperative mortality. Mechanisms underlying this effect require further study.