In-hospital changes in the red blood cell distribution width and mortality in critically ill patients with heart failure

Aims A high red blood cell distribution width (RDW) at admission or discharge is associated with a worse prognosis in hospitalized patients with heart failure (HF), and the prognostic value of the in-hospital change in RDW (?RDW) remains debatable.Methods and results We included 5514 patients with critical illness and HF from the MIMIC-IV database. The ?RDW was calculated by the RDW at discharge minus that at admission. Clinical outcomes included all-cause mortality at 90 day, 180 day, and 1 year after discharge. The median age of the patients was 73.91 years, and 46.37% were women. Kaplan-Meier curve and Cox regression analyses were used to examine the association between the ?RDW and all-cause mortality at different time points. A multivariable Cox proportional hazard model showed that the ?RDW (per 1% increase) was independently associated with all-cause mortality at 90 day, 180 day, and 1 year after adjusting for confounding factors (hazard ratio [HR] = 1.17, 95% confidence interval [CI] = 1.13-1.21, P < 0.001; HR = 1.17, 95% CI = 1.14-1.20, P < 0.001; and HR = 1.18, 95% CI = 1.15-1.20, P < 0.001, respectively). Restricted cubic splines showed a non-linear relationship between the ?RDW and the risk of clinical outcomes. High ?RDW was associated with a high risk of mortality at different time points. A subgroup analysis showed that this positive association remained consistent in pre-specified subgroups.Conclusions Our study suggests that an increased RDW during hospitalization is independently associated with short-or long-term all-cause mortality in critical-ill patients with HF.