Red cell distribution width and survival in patients hospitalized on a medical ICU.

Objectives: Red cell distribution width was shown to reliably predict mortality and morbidity in numerous clinical settings, including patients hospitalized on surgical intensive care units (ICU). Patients hospitalized on an ICU usually comprise a very heterogeneous patient population. The aim of this analysis was to investigate whether (1) RDW is related to survival outcomes in patients hospitalized on a medical ICU and (2) the prognostic value of RDW is dependent on the diagnosis that led to ICU admission.

Methods: 829 patients hospitalized on the medical ICU of a tertiary care hospital were retrospectively investigated. Patients were divided in two groups according to the main diagnosis that led to ICU admission. Group 1: non-infectious cardiac disease and group 2: other. The prognostic value of RDW for ICU- and long-term mortality was investigated for the entire patient cohort as well as for the two subgroups.

Results: The median RDW of the whole study population was 16.1%. Patients with an RDW above this threshold were exposed to an increased risk for ICU mortality (34.4% vs. 17.2%, p<0.001) and long-term mortality (log-rank p<0.001). Similarly, this cut-off was able to distinguish patients with an elevated risk for death in subgroup 2 (ICU mortality: 37.9% vs. 19.2%, p<0.001; long-term mortality: log-rank p<0.001). In subgroup 1, this value was not able to identify patients with an increased risk for ICU-mortality (17.6% vs. 11.8%, p=0.26) as well as long-term mortality (log-rank p=0.3).

Conclusions: Data of this analysis revealed that (1) RDW is a powerful predictor for ICU- and long-term mortality in patients hospitalized on a medical ICU and (2) RDW cut-offs to assess risk for death differ according to the main diagnosis that led to ICU admission.