The risk-adjusted Charlson comorbidity index as a new predictor of one-year mortality rate in elderly Chinese patients who underwent hip fracture surgery

Abstract

IntroductionRecently, many studies used the Charlson comorbidity index (CCI) to predict the postoperative mortality rate of elderly patients with hip fractures. However, as a predictor, CCI did not include other preoperative risk factors, resulting in decreasing its predictive value. Therefore, we performed a study to focus on two questions as follows: (1) What is the one-year mortality rate of elderly Chinese patients who underwent surgery for hip fracture? (2) Could risk-adjusted CCI act as a new predictor to predict the one-year mortality rate? HypothesisThe risk-adjusted CCI could exhibit a good predictive value for one-year mortality of elderly Chinese patients who underwent surgery for hip fracture. Material and methodsThis retrospective observational cohort study is based on data collected from July 2012 to April 2016. Patients aged 65 years and older who underwent hip fracture surgery were included. The clinical patient data were obtained, including gender, age, BMI, types of fracture, smoking, injury side, time from injury to surgery, and CCI. Stepwise, multiple logistic regression analysis was used to identify risk factors contributed to the occurrence of postoperative death at one-year follow-up. The risk-adjusted CCI scores of patients were calculated by the formula based on the coefficient regression and independent variables. Receiver operating characteristic (ROC) curve analysis was used for determining the diagnostic value of different factors. ResultsA total of 445 elderly patients who underwent surgery for hip fracture, including 171 males and 274 females, were enrolled in the study cohort. The mean CCI scores of all enrolled patients were 1.20±1.62. Sixty-four patients died within one year, and the one-year mortality rate was 14.38%. The multivariate logistic regression analysis reported that age, time from injury to surgery, and CCI were associated with death after surgical treatment within one year. The risk-adjusted CCI scores of patients=0.099×age (years)+0.355×time from injury to surgery (days)+0.434×CCI scores. The predictive value of the risk-adjusted CCI was highest among these risk predictors, whose AUC value was 0.816. DiscussionThe risk-adjusted Charlson comorbidity index could be used as a guide to predict one-year mortality rate in elderly Chinese patients after the surgical treatment of hip fractures. Level of evidenceIII; cohort comparative study.