Comparison of red cell distribution width and red cell distribution to albumin ratio in predicting all-cause and cardiovascular mortality in a population 65 years or older

Backgrounds While global population health and life expectancy have shown steady progress, conditions such as cardiovascular diseases, malignant tumors, chronic respiratory diseases, diabetes, and accidental injuries continue to pose serious threats to the health and life of older adults. Consequently, identifying new biomarkers for the early detection of individuals aged ≥ 65 at high risk of mortality is imperative for mitigating the mortality rates associated with these conditions. However, evidence regarding associations of the RDW and RAR with all-cause and cardiovascular mortality risk in individuals aged ≥65 years is scarce. Purpose This study investigated the relationship of the RDW and RAR with all-cause and cardiovascular mortality risk in population aged 65 years and older. Methods Participants aged ≥65 years (n = 9993) from ten National Health and Nutrition Examination Survey (NHANES) cycles (1999–2018) were included in this study. Restricted cubic spline (RCS) was used to visualize the association of the RDW and RAR with mortality risk. Time-dependent receiver operating characteristic curve (ROC) analysis was conducted to evaluate the accuracy of the RDW and RAR in predicting survival outcomes. Results During a median follow-up of 76 months, 4,089 (40.9%) of the 9993 participants aged ≥65 years died, including 1,142 (11.4%) with cardiovascular deaths. The RCS regression analysis showed a positive nonlinear association of the RDW and RAR with all-cause and cardiovascular mortality (all p < 0.05 for nonlinearity) in individuals aged ≥65 years. The time-dependent ROC curve showed that the areas under the curve (AUC) of the RDW was was 0.7094, 0.7095, 0.7177, 0.7198 and 0.6931 for 2-year, 3-year, 4-year, 5-year and 6-year all-cause mortality, respectively. Also, the AUC of the RAR was 0.7262, 0.7347, 0.6958, 0.6774 and 0.6774 for 2-year, 3-year, 4-year, 5-year and 6-year all-cause mortality, respectively. Time-dependent ROC analysis showed the AUC of the RDW was 0.6835, 0.6793, 0.6736 and 0.6029 for 2-year, 3-year, 4-year and 5-year cardiovascular mortality, respectively. Also, the AUC of the RAR was 0.7071, 0.7094, 0.6662 and 0.6954 for 2-year, 3-year, 4-year and 5-year cardiovascular mortality, respectively. Conclusion RDW and RAR are independently associated with increased all-cause and cardiovascular mortality in participants aged ≥65 years. Importantly, the RAR shows a greater predictive capability for cardiovascular mortality over a 2 to 5-year period compared to RDW.Figure 1.Time Dependent ROC