New 5-Factor Modified Frailty Index Predicts Morbidity and Mortality in Primary Hip and Knee Arthroplasty

Background: While the 11-factor modified frailty index (mFI) has been shown to predict adverse outcomes in patients undergoing total joint arthroplasty, the 5-factor index has not been evaluated in this patient population. The goal of this study was to evaluate the utility of the mFI-5 as a predictor of morbidity and mortality in patients undergoing primary total hip and knee arthroplasty. Methods: A retrospective analysis of the American College of Surgeons National Surgical Quality Improvement Program's database for patients undergoing total hip arthroplasty and total knee arthroplasty between the years 2005 and 2016 was conducted. The 5-factor score, which includes the presence of comorbid diabetes, hypertension, congestive heart failure, chronic obstructive pulmonary disease, and functional status, was calculated for each patient. Multivariate logistic regression models were used to assess the relationship between the mFI-5 and postoperative complications while controlling for demographic variables. Results: One hundred forty thousand one hundred fifty-eight patients undergoing total hip arthroplasty and 226,398 patients undergoing total knee arthroplasty were identified. After adjusting for demographic variables and comorbid conditions, logistic regression analyses revealed that the mFI-5 was a strong predictor for total complications, Clavien-Dindo grade IV complications (cardiac arrest, myocardial infarction, septic shock, pulmonary embolism, postoperative dialysis, reintubation, and prolonged ventilator requirement), surgical site infections, readmission, and 30-day mortality (P < .001). Conclusions: The mFI-5 is an independent predictor of postoperative complications including lifethreatening medical complications, surgical site infections, hospital readmission, and 30-day mortality after primary hip and knee arthroplasty. This clinical tool can be used to identify high-risk surgical patients and guide preoperative counseling to optimize outcomes. Level of Evidence: III. (C) 2018 Elsevier Inc. All rights reserved.