The revised cardiac risk index and 90-day mortality after non-cardiac surgery: a retrospective cohort study.

Background: The Revised Cardiac Risk Index (RCRI) is widely used for predicting major cardiac complications after non-cardiac surgery, but its association with 90-day all-cause mortality is less well established. This study aimed to evaluate the independent association between RCRI scores and 90-day all-cause mortality in a large, diverse cohort of patients undergoing non-cardiac surgery. Methods: We conducted a retrospective cohort study using data from 54,933 adult patients who underwent non-cardiac surgery at a tertiary care center in Singapore between 2012 and 2016. RCRI scores were calculated based on six clinical variables and categorized into four classes. The primary outcome was 90-day all-cause mortality. Survival analysis was performed using Kaplan-Meier curves and multivariable Cox proportional hazards models, with adjustments for demographic and clinical covariates. Results: A total of 735 patients (1.3%) died within 90 days postoperatively. Kaplan-Meier analysis revealed significantly poorer survival in higher RCRI classes (log-rank Conclusion: Higher RCRI scores are independently associated with increased 90-day mortality after non-cardiac surgery, demonstrating a clear dose-response relationship. These findings support the use of RCRI as a practical and effective tool for preoperative risk stratification in diverse surgical populations.