The association between the Revised Cardiac Risk Index and short-term mortality after hip fracture surgery

PURPOSE: The post-operative mortality after hip fracture surgery is high and has remained largely unchanged during the last decades. The Revised Cardiac Risk Index (RCRI) is a tool used to evaluate the 30-day risk of, among other outcomes, post-operative mortality. The aim of this study is to determine the association between the RCRI score and post-operative mortality in patients undergoing hip fracture surgery. METHODS: Data was obtained from the national hip fracture register which was cross-referenced with patients’ electronic hospital records. All adults who underwent primary emergency hip fracture surgery in Orebro County, Sweden, between January 1, 2013 and December 31, 2017, were included. Patients were divided into two cohorts: low RCRI (score = 0–1) and high RCRI (score ≥ 2). A Poisson regression model was employed to investigate the association between a high RCRI score and 30- and 90-day post-operative mortality. RESULTS: A total of 2443 patients, of whom 446 (18%) had a high RCRI score, were included in the current study. When adjusting for age, sex, comorbidities and type of surgery, the incidence of 30-day mortality increased by 46% in the high RCRI cohort (adj. IRR 1.46, 95% CI, 1.10–1.94, p = 0.010). Similar results were observed for 90-day mortality (adj. IRR 1.50, 95% CI, 1.21–1.84, p < 0.001). CONCLUSION: The RCRI is applicable to patients that undergo surgery for traumatic hip fractures. A high RCRI score is associated with an increased incidence of both 30- and 90-day post-operative mortality. Future studies to evaluate these findings are needed.