Red Cell Distribution Width Predicts Mortality in Critically Ill Patients with COPD and Atrial Fibrillation: A Retrospective Cohort Study.

BACKGROUND

Critically ill patients with COPD and atrial fibrillation (AF) face a substantially poor prognosis. Given the established prognostic value of red cell distribution width (RDW) in each condition alone, we sought to systematically evaluate its utility for mortality prediction in this population.

METHODS

This retrospective cohort study utilized data from the MIMIC-IV database. Adult ICU patients with concurrent COPD and AF were enrolled. The association between baseline RDW (analyzed both as a continuous variable and in quartiles) and the primary outcome of in-hospital mortality was assessed using multivariable logistic regression, with extensive adjustment for demographics, severity of illness, comorbidities, and treatments. Secondary outcomes included ICU, 28-day, 90-day, and 1-year all-cause mortality.

RESULTS

Among 1,252 eligible patients, a significant graded association was observed between RDW and in-hospital mortality (P for trend < 0.001). After full adjustment, each standard deviation increase in RDW was associated with a 13% rise in the odds of in-hospital death (adjusted OR 1.13, 95% CI 1.05-1.21). Patients in the highest RDW quartile had a 2.53-fold increased risk (adjusted OR 2.53, 95% CI 1.36-4.73) compared to the lowest quartile. This robust association was consistently observed for all secondary outcomes, with the risk of ICU, 28-day, 90-day, and 1-year mortality also showing significant, graded increases across RDW quartiles in the fully adjusted models (all P for trend < 0.01). Furthermore, the association remained stable across all predefined subgroup analyses.

CONCLUSION

In critically ill patients with COPD and AF, elevated baseline RDW at ICU admission is independently associated with increased short- and long-term mortality, with a graded risk increase across RDW quartiles. As a non-specific, routinely available hematologic parameter, RDW may serve as an adjunctive marker for risk stratification in this vulnerable population.