Validated Risk-Stratification System for Prediction of Early Adverse Events Following Open Reduction and Internal Fixation of Closed Ankle Fractures.

Abstract

As orthopaedic surgery moves toward bundled payments, there is growing interest in identifying patients at high risk of early postoperative adverse events. The purpose of this study was to develop and validate a risk-stratification system for the occurrence of early adverse events among patients treated with open reduction and internal fixation (ORIF) for a closed fracture of the ankle. Patients undergoing ORIF for a closed ankle fracture during the period of 2006 to 2017, as documented by the American College of Surgeons National Surgical Quality Improvement Program, were identified. For the 60% of patients randomly selected as the development cohort, multivariate Cox proportional hazards modeling was used to identify factors that were independently associated with the occurrence of adverse events (including events such as reoperation, surgical site infection, and pulmonary embolism). On the basis of these results, a nomogram analysis was used to generate a point-based risk-stratification system. To evaluate the validity of the point-based system, the system was applied to the remaining 40% of patients constituting the validation cohort and tested for its ability to predict adverse events. Of the 7,582 patients in the development cohort, 455 developed an adverse event (estimated adverse event risk of 6%). On the basis of Cox proportional-hazards regression, patients were assigned points for each of the following significant risk factors: +1 point for age of 40 to 59 years, +3 points for age of 60 to 79 years, +5 points for age of ≥80 years, +1 point for female sex, +2 points for chronic obstructive pulmonary disease (COPD), +2 points for insulin-dependent diabetes, +3 points for anemia, and +4 points for end-stage renal disease. The validation cohort included 5,263 patients. Among this second cohort, the risk-stratification system predicted the risk of early adverse events (p < 0.001; Harrell C = 0.697). The occurrence of early adverse events following ORIF for closed ankle fractures was associated with greater age, female sex, COPD, insulin-dependent diabetes, anemia, and end-stage renal disease. We present and validate a simple point-based risk-stratification system to predict the risk of early adverse events. Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.