Association of red cell distribution width to albumin ratio with risk of all-cause and cause-specific mortality: two prospective cohort studies

BackgroundThe red cell distribution width to albumin ratio (RAR) has emerged as a reliable prognostic marker for mortality in various diseases. However, whether RAR is associated with mortality remains unknown in the general population. ObjectiveExplore whether RAR is associated with all-cause and cause-specific mortality, and to elucidate the dose-response relationship between them. MethodsThis study included 50622 participants aged 18+ years from US National Health and Nutrition Examination Survey (NHANES), and 418950 participants aged 37+ years from UK Biobank. The potential association between RAR and the risk of all-cause and cause-specific mortality was evaluated by Cox proportional hazard models. Restricted cubic spline regressions were applied to estimate the possible nonlinear relationships. ResultsNHANES documented 7590 deaths over a median follow-up of 9.4 years, and UK Biobank documented 36793 deaths over a median follow-up of 14.5 years. In multivariable analysis, elevated RAR were significantly associated with a higher risk of all-cause mortality (NHANES: hazard ratio [HR]: 1.86, 95% confidence interval [CI]: 1.81-1.93; UK Biobank: HR: 2.01, 95% CI: 1.96-2.06), as well as mortality due to malignant neoplasms, heart disease, cerebrovascular diseases, respiratory diseases, diabetes mellitus, and others in both the two cohorts (all P-value < 0.05). ConclusionsHigher baseline RAR was strongly and independently associated with increased risk of all-cause and cause-specific mortality in the general population. RAR was a promising indicator that simply, reliably, and inexpensively accessible for identifying high-risk of mortality in clinical practice.