Association between red blood cell distribution width-to-albumin ratio and depression: a cross-sectional analysis among US adults, 2011-2018.

Background: Red blood cell distribution width (RDW)-to-albumin ratio (RAR) is a novel index. Its relationship with depression, a common and complex psychiatric disorder, remains unclear. This study utilized the National Health and Nutrition Examination Survey (NHANES) database to investigate this relationship.

Methods: Multivariate logistic regression, restricted cubic spline (RCS) regression, receiver operating characteristic (ROC) analysis, and sensitivity analyses were used to examine the relationship between RAR and depression based on NHANES data from 2011-2018. The study also used subgroup analyses and interaction tests to explore whether the relationship was stable across populations.

Results: RAR was positively associated with depression in 18,150 participants aged ≥ 20 years. In fully adjusted models, each one-unit increase in RAR was associated with a 22% increase in the likelihood of depression [1.22 (1.05, 1.41)]. Participants in the highest quartile of RAR had a 30% higher risk of depression than those in the lowest quartile of RAR [1.30 (1.04, 1.63)]. Subgroup analyses revealed that the association between RAR and depression was significantly stronger among men, alcohol-drinking and high-income groups.

Conclusions: Higher baseline RAR was associated with an increased risk of depression in US adults and was more informative than RDW, albumin, and hemoglobin-to-RDW ratio (HRR). Further large-scale prospective studies are needed to analyze the role of RAR in depression. These findings emphasize that RAR can be a simple, reliable and cost-effective predictor of depression in clinical practice.