Does the addition of RDW improve current ICU scoring systems?

Background: The aim of this study was to evaluate whether the addition of red blood cell distribution width (RDW) improves the prognostic value of current intensive care unit (ICU) scoring systems, namely APACHE III. Design and Methods: All patients admitted to a mixed ICU in Brisbane between June 2013 and July 2014 for whom RDW was available were included in the study. Analyses included descriptive statistics, linear regression correlation, and receiver operating characteristic (ROC) curves. Results: The study included 708 patients for whom both ICU mortality prediction and RDW were available. In univariate analysis higher RDW values were associated with increased hospital mortality. Adding RDW to APACHE III increased the area under the ROC marginally (from 0.9586 to 0.9613). RDW was not correlated with C-reactive protein, white cell count, or patient's length of stay in ICU. Conclusion: RDW was an independent predictor of mortality. The addition of RDW to APACHE III improved its mortality prediction marginally. The underlying mechanism of RDW elevation warrants further investigation.