The red cell distribution width to albumin ratio (RAR) as an independent predictor of all-cause mortality and its incremental prognostic value in elderly patients with non-valvular atrial fibrillation

Background Atrial fibrillation (AF) is common among elderly populations and is associated with high mortality. Traditional thromboembolic risk scores do not adequately capture overall mortality risk in vulnerable patients. This study assessed the red cell distribution width to albumin ratio (RAR) as a predictor of all-cause mortality and its added prognostic value in elderly patients with non-valvular AF. Methods This retrospective cohort study enrolled 1,458 consecutive inpatients with AF admitted between December 2019 and December 2023. After exclusions and loss to follow-up, the primary analysis included 1,155 complete cases. Patients were stratified by RAR tertiles. Lasso regression was used for variable selection, with RAR mandatorily included in the multivariate Cox proportional hazards model. Survival analyses utilized Kaplan-Meier curves, time-dependent ROC analysis (DeLong test), and restricted cubic splines. Three sequential models assessed incremental predictive value. Missing data were handled using multiple imputation (MI). Sensitivity analysis compared the MI cohort (n = 1,300) with the complete-case analysis (CCA) cohort (n = 1,155). Results In the complete-case cohort (n = 1,155), 194 deaths occurred over a median follow-up of 1,099.5 days. RCS analysis revealed a significant nonlinear association between RAR and all-cause mortality risk (P for nonlinearity < 0.001). Compared with the lowest RAR tertile (T1), the highest tertile (T3) was associated with significantly elevated mortality risk (multivariate-adjusted HR = 4.44; 95% CI: 2.63–7.49; P < 0.001). Incorporating RAR into a clinical prognostic model increased the AUC for predicting 3-year mortality from 0.680 to 0.812 (P < 0.001). The calibration curve showed good agreement (C-statistic = 0.8283). Sensitivity analysis using multiple imputation confirmed the robust association between RAR and all-cause mortality. Conclusions Elevated baseline RAR independently predicted all-cause mortality and offered incremental prognostic value beyond traditional risk factors in elderly patients with non-valvular atrial fibrillation.