The Risk Analysis Index is Superior to the Modified 5-Factor Frailty Index for Predicting 30-Day Mortality Following Arthroplasty for Femoral Neck Fractures

BACKGROUND Femoral neck fractures (FNFs) are common in the elderly and are typically treated operatively. Tools like frailty assessments may be critical for evaluating peri- and postoperative patient needs. Our study evaluated the utility of frailty, measured by the Risk Analysis Index (RAI) and the Modified 5-Item Frailty Index (mFI-5), in predicting 30-day mortality in patients undergoing hemiarthroplasty (HA) or total hip arthroplasty (THA) for FNFs. METHODS A national database was queried from 2015 to 2020 for patients 18 years of age or older undergoing HA or THA for FNFs. A total of 14,913 patients who had surgically managed FNFs were included. The primary outcome was 30-day mortality. Multivariate regressions were used to evaluate predictive value, and receiver operating characteristic curves assessed frailty accuracy. RESULTS Frailty as measured by the mFI-5 and RAI was predictive of increased odds of 30-day mortality in HA (RAI = odds ratio (OR): 1.46, 95% confidence interval (CI): 1.31 to 1.64; mFI-5 = OR: 1.10 (1.08 to 1.12, P < 0.001 for both)) and THA (RAI = OR: 1.15 (CI: 1.106 to 1.190, P < 0.001), mFI-5 = OR: 1.50 (CI: 1.167 to 1.923, P = 0.002)). The RAI demonstrated superior risk discrimination when compared to the mFI-5 for THA (RAI = C-statistic: 0.84, 95% CI: 0.45 to 0.83 versus mFI-5 = C-statistic: 0.69, 95% CI: 0.68 to 0.71) and HA (RAI = C-statistic: 0.74, 95% CI: 0.73 to 0.75 versus mFI-5 = C-statistic: 0.62, 95% CI: 0.61 to 0.63). CONCLUSION Frailty was found to be a predictor of mortality in patients who had FNFs undergoing THA and HA. Compared to the mFI-5, the RAI demonstrated superior predictive value for mortality across both operations. Thus, the RAI may be a powerful tool for assessing preoperative risk in patients undergoing arthroplasty for FNFs.