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.