The Association Between Revised Cardiac Risk Index and Postoperative Mortality Following Elective Colon Cancer Surgery: A Retrospective Nationwide Cohort Study

Introduction: Despite improvements in the perioperative care during the last decades for oncologic colon resection, there is still a substantial risk for postoperative complications and mortality. Opportunities exist for improvement in preoperative risk stratification in this patient population. We hypothesize that the Revised Cardiac Risk Index, a user-friendly tool, could better identify patients with high postoperative mortality risks. Methods: A retrospective analysis of operated patients between the years 2007 and 2017 was undertaken, using the prospectively recorded Swedish Colorectal Cancer Registry, which has a 99.5% national coverage for all cases of colon cancer. Patients were cross-referenced with the Swedish National Board of Health and Welfare dataset, a government registry of mortality and comorbidity data. Revised Cardiac Risk Index (RCRI) scores were calculated for each patient and stratified into four groups (RCRI 1, 2, 3, ⩾ 4). A Poisson regression model with robust standard errors of variance was employed to correlate the 90-day postoperative survival with each level of the Revised Cardiac Risk Index. Results: A total of 24,198 patients met the study inclusion criteria. 90-day postoperative mortality increased from 2.4% in patients with RCRI 1 to 10.1% in patients with RCRI ⩾ 4 ( p < 0.001). Adjusted 90-day postoperative mortality increased linearly with an increasing RCRI, where an RCRI of 2, 3, and ≥ 4 respectively led to a 46%, 80%, and 167% increased risk of mortality compared to RCRI 1 ( p < 0.001). Conclusions: A strong association between an increasing Revised Cardiac Risk Index score and increased 90-day postoperative mortality risk was detected. The Revised Cardiac Risk Index may facilitate risk stratification of patients undergoing elective colon cancer surgery.