Superior Predictive Performance of a Composite Frailty-Risk Index in Hispanic Patients Undergoing Proximal Humerus Fracture Surgery

Background Proximal humerus fractures represent a significant clinical challenge, particularly in minority patients, where accurate risk stratification remains inadequate. While individual frailty indices like the Risk Analysis Index (RAI) and modified Frailty Index-5 (mFI-5) have shown promise in predicting postoperative outcomes, no composite scoring system combining multiple validated risk assessment tools has been developed for this population. Methods This retrospective cohort study analyzed 1,259 patients who underwent proximal humerus fracture surgery from the ACS NSQIP database (2015–2021). We calculated RAI, mFI-5, Geriatric Nutritional Risk Index (GNRI), Preoperative Acute Severe Condition (PACS) scores, and ASA classification for all patients. A novel Combined ASA-RAI-Preoperative Acute Severe Condition (CARP) score was derived using multivariable regression coefficients. Primary outcomes included 30-day mortality, major complications, readmissions, reoperations, extended length of stay, and non-home discharge. Results The cohort had mean age 67.4 ± 12.1 years with 62.3% female patients. Thirty-day mortality was 0%, major complications occurred in 0.9%, and extended length of stay affected 20.1% of patients. CARP demonstrated superior or comparable predictive performance across outcomes with AUROC values ranging from 0.546–0.755. In multivariable analysis, PACS score independently predicted major complications (OR 2.96, 95% CI 1.03–8.52, p = 0.045), while GNRI independently predicted readmissions (OR 0.94, 95% CI 0.88-1.00, p = 0.038) and reoperations (OR 0.90, 95% CI 0.82–0.99, p = 0.036). Bootstrap validation confirmed robust internal validity with minimal optimism bias. Conclusions The novel CARP score provides enhanced risk stratification for proximal humerus fracture surgery patients, demonstrating superior predictive performance compared to individual indices and offering clinicians a comprehensive tool for preoperative decision-making and patient counseling.