Characteristics of included patients.

Background
Red blood cell distribution width/albumin ratio (RAR) has been reported as an independent risk factor for diabetic retinopathy (DR), while its association and predictive value in the prognosis of DR patients has not been reported. This study aims to explore the association and predictive value of RAR in the prognosis of DR patients.
Methods
This was a retrospective cohort study based on the National Health and Nutrition Examination Survey (NHANES). The independent variable was RAR, and dependent variables were all-cause mortality and cardiovascular diseases (CVD) mortality. The association between RAR and the risk of all-cause mortality and CVD mortality was assessed using univariate and multivariate cox regression models. The results were shown as HR (hazard ratio) with 95% confidence intervals (CIs). Subgroup analysis based on age or hyperlipidemia was performed. The discrimination of the prediction model was assessed using concordance index (C-index).
Results
A total of 725 eligible patients were finally included in this study. The increase of RAR was associated with increased risk of all-cause mortality (HR: 1.15, 95%CI: 1.01–1.31) and CVD mortality (HR: 1.35, 95%CI: 1.12–1.63) after adjusting the covariates. We also found the significant association between higher RAR and higher risk of CVD mortality in DR patients with age < 65 years (HR: 1.35, 95%CI: 1.09–1.67) and with hyperlipidemia (HR: 1.34, 95%CI: 1.10–1.64). C-index of RAR for all-cause mortality and CVD mortality was 0.63 (95%CI: 0.59–0.67) and 0.65 (95%CI: 0.59–0.71), respectively.
Conclusions
Higher RAR was associated with the higher risk of all-cause mortality and CVD mortality in DR patients, and RAR may be a useful predictor for the prognosis of DR patients.