# Social Determinants of Health and 30-Day Mortality After Inpatient Elective Surgery

## TL;DR

Lower neighborhood income is linked to higher post-surgery death rates in a universal healthcare system, even after adjusting for patient and hospital factors.

## Contribution

Demonstrates that social determinants like neighborhood income affect surgical outcomes in universal healthcare systems.

## Key findings

- Patients from lowest-income areas had 52% higher odds of 30-day mortality compared to highest-income areas.
- The association between income and mortality showed a dose-response pattern across income quintiles.
- Immigration-related factors were not significantly associated with mortality after risk adjustment.

## Abstract

This cohort study examines the association of neighborhood-level income, immigration status, and migration recency with 30-day mortality among adults in Ontario, Canada, who underwent inpatient elective surgical procedures between 2017 and 2023.

How are social determinants of health (neighborhood income, immigration status, and migration recency) associated with 30-day mortality after inpatient elective surgery in a universal health care system?

In this cohort study including 1 036 759 patients who underwent scheduled surgical procedures, patients from the lowest-income neighborhoods had higher odds of 30-day mortality than those from the highest-income areas, even after adjusting for patient, procedure, and hospital factors. The association showed a dose-response pattern and persisted across study periods; immigration-related factors were not associated with mortality.

In this study, lower neighborhood income was associated with higher postoperative mortality, suggesting that improving surgical outcomes may require addressing disparities in social determinants of health.

Prior research conducted in private for-profit health care systems has suggested that social determinants of health (SDOH) play a role in adverse postoperative outcomes. Whether these findings translate to universal health care systems is unknown.

To quantify the association of SDOH with risk of 30-day mortality after scheduled inpatient surgery.

This cohort study was conducted in Ontario, Canada’s most populous province. The cohort included consecutive adult patients (aged ≥18 years) who were eligible for Ontario’s universal health insurance and underwent a scheduled inpatient surgical procedure between January 1, 2017, and December 31, 2023. Diagnostic and procedural, demographic, vital statistics, and other data were obtained from linked health administrative databases.

SDOH including neighborhood income, immigration status, and migration recency.

Death within 30 days of index surgery. Logistic regression models were used to estimate the adjusted and unadjusted odds ratios (AORs and ORs) of the association of each SDOH with 30-day mortality.

Overall, 1 036 759 patients (median [IQR] age, 66 [56-74] years; 526 158 females [50.8%]) who underwent a range of scheduled inpatient surgical procedures were included. Of these patients, 1780 (0.9%) from the lowest-income areas died, as did 1307 (0.6%) from the highest-income areas. Patients from the lowest-income areas were at 52.0% increased odds of death (OR, 1.52; 95% CI, 1.42-1.64) compared with those from the highest-income areas. This association persisted with models partially adjusted for demographic and procedural factors (AOR, 1.54; 95% CI, 1.44-1.66) and fully adjusted for comorbidities (AOR, 1.43; 95% CI, 1.33-1.54). A dose-response association was demonstrated between neighborhood income and mortality, with odds of death increasing with diminishing income (eg, quintile 3 vs quintile 5: AOR, 1.18 [95% CI, 1.10-1.27]; quintile 2 vs quintile 5: AOR, 1.32 [95% CI, 1.22-1.42]). There was evidence of effect modification of the association between neighborhood income and mortality by procedure complexity (eg, effect estimate for quintile 4 and high complexity: –0.0776 [95% CI, –0.2722 to 0.1169]; P = .002). Immigrant and refugee status and recent migration (<5 years) demonstrated reduced odds of mortality in unadjusted analyses, but these associations diminished with risk adjustment.

In this cohort study, residency in lowest-income neighborhood was associated with increased risk of postoperative mortality despite adjustment for patient, procedure, and hospital factors. Improving postoperative outcomes likely requires addressing underlying SDOH disparities.