Association of red cell distribution width and its changes with the 30-day mortality in patients with acute respiratory failure: An analysis of MIMIC-IV database

BACKGROUND: Acute respiratory failure (ARF) is a common disease in the intensive care units (ICUs) with high risk of mortality. The red cell distribution width (RDW) is one of baseline ICU indicators which can be easily available, and has been used in the long-term prognostic analyses of diseases. However, no studies have explored the role of baseline RDW and its change during hospitalization in in-hospital mortality in ARF. Herein, this study aims to explore the association between RDW and its changes and the 30-day mortality in ARF patients. METHODS: Demographic and clinical data of 7,497 patients with ARF were extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database in 2012–2019 in this retrospective cohort study. Univariable and multivariable Cox regression analyses were used to explore the association between RDW and its changes and 30-day mortality with hazard ratios (HRs) and 95% confidence intervals (CIs). Subgroup analyses of different baseline RDW levels were also performed. We then assessed the predictive performance of RDW changes combined with the Sequential Organ Failure Assessment (SOFA) score on 30-day mortality using receiver operator characteristic curves (ROCs) with areas under curve (AUCs). RESULTS: Totally, 2,254 (30.07%) patients died in 30 days. After adjusting for covariates, we found that high baseline RDW [HR = 1.25, 95%CI: (1.15–1.37)] and RDW changes ≥0.3% [HR = 1.12, 95%CI: (1.01–1.24)] were both related to an increased risk of 30-day mortality. In patients whose baseline RDW level ≥14.9%, RDW changes ≥0.3% was also associated with an increased risk of 30-day mortality [HR = 1.19, 95%CI: (1.05–1.35)]. Moreover, the predictive value of RDW changes combined with SOFA on 30-day mortality was a little better than that of single SOFA score, with AUCs of 0.624 vs. 0.620. CONCLUSION: High baseline RDW level and its changes during hospitalization was relate to the increased risk of 30-day mortality in ARF, and the predictive value of RDW changes for ARF short-term mortality is still needed exploration.