Red cell distribution width is associated with hospital mortality in unselected critically ill patients

Red cell distribution width (RDW) is a variability of red cell sizes and has been associated with outcomes in many clinical settings. Its prognostic value in intensive care unit (ICU) has been reported but requires confirmation. The study aimed to investigate the role of RDW in predicting hospital mortality in critically ill patients.

This is a retrospective study conducted in a 24-bed ICU of a tertiary teaching hospital. Data on demographic characteristics and laboratory measurements were collected from medical information database. Baseline variables were compared between survivors and nonsurvivors. The primary endpoint was hospital mortality; and ICU length of stays (LOS) were compared between patients with RDW >14.8% and ≤14.8%. The predictive value of RDW was also measured using receiver operating characteristic (ROC) curves. Two-sided P<0.05 was considered to be statistically significant.

A total of 1,539 patients were enrolled during study period, including 1,084 survivors and 455 nonsurvivors. In univariate analysis, variables such as age, sex, primary diagnosis, C-reactive protein (CRP), RDW and albumin were significantly associated with hospital mortality. RDW remained significantly associated with mortality after adjustment for sex, age, Charlson index albumin and CRP, with an odds ratio of 1.1 (95% CI: 1.03-1.16). Diagnostic performance of RDW in predicting mortality appeared to be suboptimal (AU-ROC: 0.62). Changes in RDW during a short follow up period were not associated with mortality.

RDW measured on ICU entry is associated with hospital mortality. Patients with higher RDW will have longer LOS in ICU. Repeated measurements of RDW provide no additional prognostic value in critically ill patients.