Prognostic significance of changes in red cell distribution width in an internal medicine ward

• Changes in RDW are common during hospitalization in internal medicine wards.
• RDW changes could be a marker for the severity of underlying illness/comorbidities.
• Repeated RDW assessment may improve risk stratification in internal medicine wards.

BackgroundThe prognostic significance of red cell distribution width (RDW) during hospitalization in internal medicine wards was not sufficiently investigated.MethodsDemographic, clinical and laboratory characteristics were collected from 586 internal medicine inpatients. Following discharge, all-cause mortality was recorded. The data were compared according to ΔRDW during hospitalization (primary endpoint), and to normal (≤ 14.7%) vs. high (> 14.7%) RDW values on admission/discharge (secondary endpoint).ResultsGroup A (rise in RDW, ΔRDW + 0.4%), group B (nonsignificant RDW changes, ΔRDW up to 0.4%) and group C (drop in RDW, ΔRDW − 0.4%) comprised 20.3%, 60.6% and 19.1% of the patients, respectively. High RDW on admission and discharge was found in 31.7% and 31.4% of patients, respectively. In-hospital mortality rates were higher in group A than in groups B and C (14.3% vs. 2.8% and 4.5%, p < 0.001), whereas increased long-term (median follow-up 43 months) mortality rates were observed in group C (35.7%), compared to groups A (17.6%) and B (23.4%), p = 0.009. Mortality rates were significantly higher (p < 0.001) in patients with high than normal RDW on admission (51.1% vs. 20.3%) and on discharge (50.5% vs. 20.6%). Every 1% increment of RDW on admission and discharge strongly predicted mortality (relative risks 1.21 and 1.21; 95% confidence intervals 1.12–1.31 and 1.13–1.32, respectively).ConclusionsHigh RDW on admission and discharge predicted poor prognosis. Rising RDW throughout hospitalization was associated with higher in-hospital mortality, while an elevated long-term mortality rate was observed in patients with declining RDW. Repeated RDW measurements may improve risk stratification for internal medicine inpatients.