Red cell distribution width and outcome in patients with septic shock

Red cell distribution width (RDW) is reflective of systemic inflammation. The objective of this study was to investigate the association between RDW (on day 1 of development of septic shock) and mortality.

A total of 279 patients with septic shock were included. We categorized the patients into quintiles based on RDW as follows: <13.5%, 13.5% to 15.5%, 15.6% to 17.5%, 17.5% to 19.4%, and >19.4%.

Red cell distribution width was a strong predictor of hospital mortality with a significant risk gradient across RDW quintiles after multivariable adjustment: RDW 13.5% to 15.5% (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.0-23.4; P = .06); RDW 15.6% to 17.5% (OR, 8.0; 95% CI, 1.5-41.6; P = .01); RDW 17.6% to 19.4% (OR, 25.3; 95% CI, 4.3-149.2; P < .001); and RDW >19.4% (OR, 12.3; 95% CI, 2.1-73.3; P = .006), all relative to patients with RDW <13.5%. Similar significant robust associations were present for intensive care unit mortality. Estimating the receiver-operating characteristic area under the curve (AUC) showed that RDW has very good discriminative power for hospital mortality (AUC = 0.74). The AUC was 0.69 for Acute Physiologic and Chronic Health Evaluation II (APACHE II) and 0.69 for sequential organ failure assessment (SOFA). When adding RDW to APACHE II, the AUC increased from 0.69 to 0.77.

Red cell distribution width on day 1 of septic shock is a robust predictor of mortality. The RDW is inexpensive and commonly measured. The RDW fared better than either APACHE II or SOFA, and the sum of RDW and APACHE II was a stronger predictor of mortality than either one alone.