Postoperative outcomes among Northern versus Southern Ontario patients undergoing common intermediate- to high-risk elective surgeries: a population-based cohort study

PURPOSE: Northern Ontario residents experience multiple health disparities compared with those in Southern Ontario. It is unknown whether this leads to differences in surgical outcomes. We sought to compare postoperative outcomes of patients from Northern and Southern Ontario. METHODS: We conducted a retrospective population-based cohort study using linked administrative health care data to identify all adult patients undergoing selected elective intermediate- to high-risk noncardiac surgeries in Ontario, Canada between 2009 and 2022. The primary outcome was 30-day mortality following surgery. The secondary outcomes were number of days alive at home, hospital length of stay, total health care system costs, discharge disposition, and readmissions. We used regression models to estimate the adjusted association between the exposure and outcomes. RESULTS: This study identified 562,115 patients, including 41,191 (7.3%) from Northern Ontario. We did not find strong evidence that mortality rates were higher for Northern vs Southern Ontario residents (adjusted odds ratio, 1.04; 95% confidence interval CI, 0.85 to 1.27). Health system costs were lower for Northern Ontario residents at 30 days adjusted ratio of mean (RoM), 0.92; 95% CI, 0.89 to 0.96 and at 365 days (adjusted RoM, 0.93; 95% CI, 0.90 to 0.96). Hospital length of stay was longer for Northern Ontario residents (adjusted RoM, 1.06; 95% CI, 1.01 to 1.11). The number of days alive at home and rate of readmission were not statistically different between the two groups. CONCLUSION: Northern Ontario residency was not associated with increased odds of mortality after intermediate- to high-risk elective noncardiac surgery. Overall, we found no clinically meaningful differences in postoperative outcomes between patients from Northern and Southern Ontario.