Association between the red cell distribution width-to-platelet ratio and 30-day all-cause mortality among patients with acute respiratory failure: a retrospective analysis of the MIMIC-IV database.

BACKGROUND: The importance of the red cell distribution width (RDW)-to-platelet ratio (RPR) in clinical practice has been described in various diseases. However, the prognostic importance of the RPR in patients with acute respiratory failure (ARF) remains unclear. The aim of the present study was to investigate the association of the RPR with 30-day all-cause mortality among ARF patients in the intensive care unit (ICU). METHODS: Data were obtained from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database (version 3.1). The study population was divided into different groups based on RPR quartiles (Q1-Q4). The outcome of interest was all-cause mortality within 30 days. Cox proportional regression analysis was performed to determine the relationship between the RPR and 30-day mortality, and Kaplan‒Meier (K‒M) analysis was conducted to obtain survival curves. Additionally, restricted cubic spline (RCS) analysis was utilized to determine whether there was a nonlinear correlation between the RPR (as a continuous variable) and 30-day mortality in ARF patients. Subgroup analysis was subsequently performed to determine whether the association between the RPR and 30-day mortality in ARF patients was stable across the subgroups. RESULTS: A total of 10,912 ARF patients were enrolled in this study. The 30-day mortality rate was 27.2%. Cox proportional regression analysis revealed that an elevated RPR was associated with an increased risk of 30-day mortality in ARF patients. Furthermore, K‒M survival analyses revealed that patients with higher RPR levels demonstrated significantly higher all-cause mortality rates within 30 days of admission than patients with lower RPRs. The RCS model illustrated the linear relationship between a higher RPR and increased risk of mortality in this specific patient population. The final subgroup analysis indicated no significant interaction effect of the RPR in most of the subgroups. CONCLUSIONS: This study demonstrated that RPR levels were significantly associated with short-term prognosis in patients with ARF and that a high RPR could serve as an independent predictor of all-cause mortality at 30 days in patients with ARF.