Red Blood Cell Distribution Width-to-Albumin Ratio as Novel Biomarker Predicting Mortality in Cardiovascular Disease: A Systematic Review and Dose-Response Meta-Analysis

Red blood cell distribution width (RDW) and albumin separately have been used as mortality predictors for people with cardiovascular disease (CVD). This study aims to explore whether the RDW-to-albumin ratio (RAR) could provide a better prognostication in the CVD population. A systematic search of suitable studies was conducted in PubMed, Web of Science, Scopus, and ProQuest until February 1, 2024. Mortality and length of stay outcomes of the highest vs lowest RAR tertile were pooled using hazard ratio (HR) and standardized mean difference (SMD), respectively. Additionally, a dose-response meta-analysis was performed. Publication bias, subgroup, and sensitivity analyses were conducted to address the causes of heterogeneity. Sixteen studies with 30,933 participants were included in the meta-analysis. Pooled results showed that patients with higher RAR faced a significantly higher risk of mortality (HR 1.88, 95%CI 1.59–2.23). Nonlinearity was observed in the dose-response relationship. Using a reference value of 3 ml/g, each 1 ml/g increase in RAR corresponded to a 27% rise in the mortality HR (HR 1.27, 95%CI 1.16–1.39). Our study demonstrated that elevated RAR values were significantly associated with higher mortality in CVD and exhibited a positive dose-response relationship, suggesting its potential as a novel prognostic biomarker for CVD.