Red Blood Cell Distribution Width-to-Albumin Ratio (RAR) Is an Independent Predictor of Mortality in Non-Anemic Elderly with Hip Fractures

Taiguo Ning,* Zhenning Liu,* Liping Pan,* Hao Wang, Guanghua Liang, Ruowen Yu, Yongping Cao Orthopedic Department, Peking University First Hospital, Beijing, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yongping Cao, Orthopedic Department, Peking University First Hospital, Beijing, 100034, People’s Republic of China, Email [email protected]: Hip fractures in elderly patients are associated with high morbidity and mortality, and effective prognostic biomarkers to guide risk stratification remain scarce. The red blood cell distribution width-to-albumin ratio (RAR), reflecting both inflammatory and nutritional status, has shown predictive value in other diseases but has not been evaluated in hip fractures.Methods: This retrospective single-center study analyzed 622 elderly patients with hip fractures (aged ≥ 70 years) treated at Peking University First Hospital between 2015 and 2021. Patients were stratified into quartiles according to RAR (Q1–Q4), and mortality outcomes were assessed at 30 days, 3 months, 6 months, and 1 year after surgery. The prognostic significance of RAR was examined using Kaplan–Meier survival analysis, Cox proportional hazards models, and receiver operating characteristic (ROC) curves.Results: Mortality increased progressively across RAR quartiles, with patients in the highest quartile (Q4) showing a 1-year mortality rate of 21.13%, compared with 4.08% in the lowest quartile (Q1) (P< 0.001). Multivariable Cox regression analysis demonstrated that RAR was an independent predictor of mortality in non-anemic patients (Q4 vs. Q1: HR=12.52, 95% CI 3.18– 49.24, P< 0.001), whereas no significant association was observed in anemic patients (Q4 vs. Q1: HR=1.89, 95% CI 0.83– 4.30, P=0.129). ROC analysis further indicated that RAR provided superior discriminatory performance compared with red blood cell distribution width (RDW) alone.Conclusion: RAR represents a novel and independent predictor of postoperative mortality in elderly non-anemic patients with hip fractures, offering greater predictive accuracy than RDW alone. Incorporating RAR into clinical risk stratification models may improve prognostic assessment and support individualized treatment planning. Validation through multicenter prospective studies and further investigation of underlying mechanisms are warranted.Keywords: RDW/ALB, Hip fracture, mortality, older people