The incremental prognostic effect of red blood cell distribution width in 28-day mortality among critically ill patients with HFpEF.

Background: The prognostic impact of red blood cell distribution width (RDW) on adverse outcomes in patients with heart failure with preserved ejection fraction (HFpEF) has been established. However, its non-linear relationship and incremental prognostic value in critically ill HFpEF patients remain insufficiently explored. Methods: A retrospective cohort study was conducted involving 3802 HFpEF patients from the Medical Information Mart for Intensive Care IV (MIMIC-IV, v3.1) database. Multivariable Cox regression and restricted cubic spline (RCS) analyses were performed to evaluate the association between RDW and 28-day mortality, adjusting for potential confounders. A prediction model was constructed by the least absolute shrinkage and selection operator (Lasso)-Cox regression, and receiver operating characteristic (ROC) curve was utilized to assessed the incremental prognostic effect of RDW on 28-day mortality prediction. Results: Within the final cohort of 1962 HFpEF patients, the incidence of 28-day mortality showed a significant increase across RDW tertiles (T1 9.4% vs T2 13.1% vs T3 22.9%, Conclusions: This study established a significant linear association between RDW at admission and poor prognosis in critically ill patients with HFpEF. Higher RDW levels were associated with increased 28-day mortality risk, suggesting that it may be a relevant biomarker for mortality risk stratification in HFpEF patients.