Red cell distribution width (RDW), RDW to albumin ratio (RAR), and long-term mortality in diabetic neuropathy: A NHANES analysis, 1999-2019.

Aims: We aimed to explore associations between Red cell distribution width (RDW), RDW to albumin ratio (RAR), and long-term all-cause and cardiovascular disease (CVD) mortality in adults with diabetes and DN.

Methods: This study included adults aged ≥40 years with DN from the National Health and Nutrition Examination Survey from 1999 to 2004, followed through 2019. Cox proportional hazards models were used to assess associations between RDW, RAR, and all-cause and CVD mortality. Predictive accuracy was determined using area under the curve (AUC) by receiver operating characteristic analyses.

Results: Data of a total of 624 participants with DN were analyzed. Each unit increase in RDW significantly increased all-cause mortality by 12% (adjusted hazard ratio (aHR) = 1.12, 95% CI: 1.05-1.20) and CVD mortality by 15% (aHR = 1.15, 95% CI: 1.02-1.31), while each unit increase in RAR increased all-cause mortality by 73% (aHR = 1.73) and CVD mortality by 93% (aHR = 1.93). In the highest versus lowest quartiles, RDW (aHR = 1.89) and RAR (aHR = 2.91) were associated with higher all-cause mortality risk, and even higher risk for CVD mortality (RDW: aHR = 2.86; RAR: aHR = 4.84). The AUC for 5-year predictions was RDW 0.825 and RAR 0.846 for all-cause mortality, and RDW 0.811 and RAR 0.814 for CVD mortality.

Conclusions: RDW and RAR are strong predictors of long-term mortality in individuals with DN. RAR demonstrates stronger associations and higher predictive accuracy than RDW, particularly in predicting CVD mortality.