Background: Different accessible and low-cost biomarkers have been investigated to stratify patients with acute heart failure (AHF). One of them is the red cell distribution width (RDW), which proved to be a greater prognostic marker of mortality than other conventional markers. Objective: Therefore, the objective of our study is to determine whether the anemic status modifies the magnitude of association between high RDW and 1-year mortality in patients with AHF. Design: Observational, analytical, retrospective cohort study. Methods: We included participants ⩾18 years old hospitalized with a diagnosis of AHF. As an association measure, a crude and adjusted generalized linear model of the Poisson family calculated the risk ratio (RR) with a 95% confidence interval (95% CI). Results: In all, 709 participants with an average age of 73.48 years were included. At 1 year, the risk of ...