Healthcare systems and hospitals operate differently on weekends than on weekdays. This leads to the “weekend effect,” where patient outcomes may worsen. This effect primarily impacts patients who underwent surgery just before the weekend and require post-operative care during non-working days. Some research studies focused on mortality across subspecialties showed conflicting findings.
The recent retrospective cohort study published in JAMA Network Open aimed to assess whether surgeries before the weekend period led to worse outcomes than those after the weekend.
This population-based study included adult patients in Ontario, Canada, who underwent one of 25 common surgeries between January 1, 2007, and December 31, 2019. All patients’ data were collected from various healthcare databases such as the Ontario Health Insurance Program database, Canadian Institute for Health Information Discharge Abstract Database, Same Day Surgery databases, Registered Persons Database, and ICES Physician Database. All the patients were followed for 30 days (Short term), 90 days (Intermediate term), and one year (Long term).
Patients aged <18 years, those with missing information, non-residents of Ontario, those who underwent multiple surgeries on the same day, and those who did not undergo the surgery on the day before or after the weekend were excluded from the study. The primary endpoints were included 30-day readmissions, complications, and mortality measured. Secondary endpoints were length of stay (LOS), duration of surgery, as well as complications, mortality, and readmission at 90 days and 1 year.
A total of 429,691 patients (mean age = 58.6±16.9 years, 62.8% female) were included in this study. Patients were divided into two groups preweekend (n = 199744) and postweekend (n = 229947) groups. Approximately 88.2% of patients were from urban areas. The results showed that patients in the preweekend group experienced higher composite primary outcomes compared to patients in the postweekend group (8.49% [95% Confidence Interval (CI), 7.61%-9.46%] vs 8.13% [95% CI, 7.27%-9.10%]) with adjusted odds ratio (aOR) of 1.05 (95% CI, 1.02-1.08) and risk-adjusted absolute difference of 0.36% (95% CI, 0.21%-0.49%).
The preweekend group was associated with enhanced odds of mortality (aOR, 1.09 [95% CI, 1.03-1.16]) and longer LOS (adjusted relative risk, 1.06 [95% CI, 1.04-1.08]) at the short-term follow-up period.
Patients in the preweekend group had higher rates of composite primary measures compared to patients in the post-weekend group at intermediate follow-up period (12.14% [95% CI, 11.28%-13.06%] vs. 11.58% [95% CI, 10.76%-12.45]; aOR, 1.06 [95% CI, 1.03-1.09]) with risk-adjusted absolute difference of 0.57% (95% CI, 0.39%-0.74%). Similarly observed at long-term follow-up period (22.64% [95% CI, 21.04%-24.38%] vs. 21.84% [95% CI, 20.49%-23.29%]; aOR, 1.05 [95% CI, 1.02-1.09]) with risk-adjusted absolute difference 0.81% (95% CI, 0.58%-1.04%).
Furthermore, odds of mortality were enhanced in the preweekend group compared to the post-weekend group at 90 days, with an aOR of 1.10 (95% CI, 1.03-1.17) and at 1 year, with an aOR of 1.12 (95% CI, 1.08-1.17).
This study had several limitations, mainly due to its observational type and administrative data use. These include the lack of preoperative data, the risk of immediate preoperative occurrences, and ecological bias affecting the long-term outcomes.
In conclusion, this study identified a small but significant weekend effect across all surgical specialties. However, a significant rise in perioperative complications and long-term mortality was reported among patients who underwent surgery just before the weekend. Healthcare systems must evaluate this phenomenon to ensure consistent, high-quality care of patients regardless of the day of the week.
Reference: Ranganathan S, Riveros C, Tsugawa Y, et al. Postoperative outcomes following preweekend surgery. JAMA Netw Open. 2025;8(3):e2458794. doi:10.1001/jamanetworkopen.2024.58794
