Risk Analysis Index for Estimation of 30-Day Postoperative Mortality in Hip Fractures

Importance: Hip fractures present a substantial public health challenge, with projections of more than 500 000 per year by 2040. As such, frailty indices such as the Revised Risk Analysis Index (RAI) and the Modified Five-Item Frailty Index (mFI-5) have been recently investigated as metrics for preoperative risk stratification for these patients. Objective: To understand the accuracy of frailty, as measured by the RAI and the mFI-5, for estimating 30-day mortality following surgically managed hip fractures. Design, Setting, and Participants: This retrospective cross-sectional analysis used the American College of Surgeons' National Surgical Quality Improvement database. Patients aged 65 years old with surgically managed traumatic hip fracture from 2015 to 2019 were included. Frailty was evaluated using the RAI, a 5-domain scale with 14 weighted variables graded from 0 to 81, and the mFI-5, a 2-domain scale with 5 unweighted variables graded from 0 to 5; for both, a higher score denotes worse frailty. Data collection occurred from May to June 2024. Exposure: Diagnosis of hip fracture and undergoing surgical fixation, hemiarthroplasty, or total hip arthroplasty. Main Outcomes and Measures: The primary outcome was 30-day mortality. Multivariable regression was conducted to assess the estimating value of frailty scales. Discriminatory accuracy was assessed using a receiver operating characteristic curve and quantified using a C-statistic. Results: The cohort consisted of 114 359 patients (70 038 female 69.9%; median IQR age, 84 77-89 years) with 51 071 prefrail patients (44.7%) according to the mFI-5 and 31 883 very frail patients (27.9%) according to the RAI comprising the largest frailty groups. Increasing frailty status was associated with greater odds ratio (OR) for 30-day mortality for both the mFI-5 (prefrail OR, 1.35 95% CI, 1.24-1.47; frail OR, 2.11 95% CI, 1.94-2.30; severely frail OR, 3.53 95% CI, 3.20-3.90; P < .001 for all) and RAI (normal OR, 1.55 95% CI, 1.35-1.79; frail OR, 2.97 95% CI, 2.59-3.42; very frail OR, 6.17 95% CI, 5.38-7.08; P < .001 for all). The RAI demonstrated superior discriminatory accuracy for 30-day mortality compared with the mFI-5 (area under the receiver operating characteristic curve, 0.73 95% CI, 0.72-0.73 vs 0.61 95% CI, 0.60-0.62; P < .001). Conclusions and Relevance: In this cross-sectional study of 114 359 patients, the RAI demonstrated superior odds and discriminatory accuracy for estimating 30-day mortality following surgical management of hip fractures. The RAI may be considered as a risk stratification tool for orthopedic surgeons to adjunct surgical planning, thereby reducing postoperative mortality.