Association of red cell distribution width-to-albumin ratio with mortality in adults with low muscle mass: A retrospective cohort study.

BackgroundThe red cell distribution width-to-albumin ratio (RAR) is a novel composite biomarker that reflects both inflammatory and nutritional status. Although the RAR has been associated with various chronic disease outcomes, its relationship with mortality risk in adults with reduced muscle mass has not been systematically evaluated.MethodsWe analyzed data from 1494 adults with reduced muscle mass enrolled in 6 cycles of the US National Health and Nutrition Examination Survey (2003-2006 and 2011-2018). Kaplan-Meier survival analysis, Cox proportional hazards regression, restricted cubic spline models, and time-dependent receiver operating characteristic curves were used to comprehensively assess the association between RAR and mortality risk. Subgroup and interaction analyses were conducted to evaluate the robustness of the findings.ResultsDuring a median follow-up of 104 months, a higher RAR was linearly associated with increased risks of all-cause and cardiovascular mortality. Compared with Q1, Q4 was associated with a 154% and 216% higher risk of all-cause and cardiovascular mortality, respectively. These associations were generally consistent across subgroups, with a significant interaction by sex indicating stronger associations among men. Time-dependent area under the curve analyses demonstrated that the RAR outperformed the neutrophil-to-lymphocyte ratio, systemic immune-inflammation index, and neutrophil-to-albumin ratio at most time points, with the exception that the neutrophil-to-lymphocyte ratio slightly exceeded RAR for 5-year cardiovascular mortality.ConclusionRAR is positively associated with mortality risk in adults with reduced muscle mass. RAR may serve as a practical biomarker for risk stratification in this population.