Association of red blood cell distribution width-to-albumin ratio with all-cause and cardiovascular mortality in adults with hyperuricemia: A cohort study from NHANES 1999 to 2018

The red blood cell distribution width-to-albumin ratio (RAR) reflects the combined impact of inflammation, oxidative stress, and nutritional status. However, its prognostic value for all-cause and cardiovascular disease (CVD) mortality in individuals with hyperuricemia (HUA) remains unclear. This study aimed to investigate the association between RAR and mortality risk in this particular population. Adult participants diagnosed with HUA from the National Health and Nutrition Examination Survey conducted between 1999 and 2018 were enrolled in this research. Multivariable Cox regression models and smooth curve fitting were used to investigate the associations between RAR and the risks of all-cause and CVD mortality. Kaplan-Meier survival analysis was utilized to compare survival probabilities across the different RAR quartiles (Q1-Q4). Stratified analyses were conducted to assess potential effect modification and identify subgroups at elevated risk. A total of 5735 participants with HUA were enrolled in this study. After adjusting for covariates, elevated RAR was independently associated with increased risks of both all-cause mortality (hazard ratio for Q4 vs Q1 = 3.45; 95% confidence interval: 2.58-4.61; P < .001) and CVD mortality (hazard ratio for Q4 vs Q1 = 3.31; 95% confidence interval: 1.90-5.76; P < .001). The associations exhibited nonlinear, threshold-dependent characteristics, with inflection points identified at RAR values of 3.87 for all-cause mortality and 3.71 for CVD mortality. Stratified analyses revealed significant effect modification by age for both outcomes (P for interaction < .001) and by gender, specifically for CVD mortality (P for interaction = .028). Increased RAR is independently correlated with heightened risks of all-cause and CVD mortality among American adults with HUA. These findings underscore the potential utility of RAR in stratifying mortality risk within this demographic.