The Red Cell Distribution Width Strongly Predicts Mortality Among Patients Evaluated by Pulmonary Function Testing

Abstract

Abstract SESSION TYPE: COPD Posters IIPRESENTED ON: Wednesday, October 24, 2012 at 01:30 PM - 02:30 PMPURPOSE: Historically, the red cell distribution width (RDW) was utilized after an anemia diagnosis to determine its etiology. In 2007, we first reported that RDW was a powerful predictor of mortality among cardiovascular patients, which was subsequently replicated in various heart and vascular disease populations. This study evaluated whether the RDW is associated with survival and hospital admission-free survival among patients undergoing pulmonary function testing (PFT).METHODS: Patients (N=2,629) evaluated by PFT between October, 2002, and October, 2011, were tested for RDW levels using the complete blood count (CBC) panel. All-cause mortality was determined using local, state, and national death registries in December, 2011. Admission to one of Intermountain Healthcare's 22 hospitals in Utah was determined by electronic query of a central electronic data warehouse. Cox regression was used to adjust for patient age, sex, body mass index, forced vital capacity, the other CBC components, and all independent variables in the basic metabolic profile.RESULTS: During a mean of 2.8 years of follow-up (max: 9.2 years), 363 patients (6.0%) died and 1,447 (55.0%) experienced a hospital admission following the PFT. Average age was 60.0 years and 54% were female. Mean RDW was significantly higher among decedents (16.3 vs. 15.0, palt;0.001). Modeled as a continuous variable, RDW strongly predicted mortality (adjusted hazard ratio [HR]=1.11 per mg/dL increase, 95% CI=1.07, 1.16; palt;0.001). Survival was 91.7%, 89.3%, 89.1%, 85.4%, and 74.0% in RDW quintiles 1-5 (≤13.3, 13.4-14.1, 14.2-15.0, 15.1-16.6, agt;16.6 mg/dl), respectively. In Cox regression, RDW quintile 5 vs. 1 had HR=2.68 (95% CI=1.80, 3.98; palt;0.001), with a graded association (HR=1.62, 1.30, and 1.47 for quintiles 4, 3, and 2 vs. 1, respectively). For hospital admission, RDW also significantly stratified risk (quintile 5 vs. 1: HR=1.91, 95% CI=1.56, 2.33; palt;0.001) with a graded association (HR=1.38, 1.59, and 1.35 for quintiles 4, 3, and 2 vs. 1).CONCLUSIONS: RDW was a powerful predictor of survival and hospital admission among patients initially evaluated by PFT. This is consistent with the reported role of RDW in risk among other populations and suggests that higher RDW indicates a generally lower level of health. Further study of the role of RDW in pulmonary patient risk is indicated.CLINICAL IMPLICATIONS: Elevated RDW may indicate a need for more intense preventive therapies or diagnostic testing to reduce future risk.DISCLOSURE: Benjamin Horne: Grant monies (from industry related sources): GlaxoSmithKline clinical research supportMatthew Hegewald: Grant monies (from industry related sources): GlaxoSmithKline clinical research supportJoseph Muhlestein: Grant monies (from industry related sources): GlaxoSmithKline clinical research supportElizabeth Huggins: Grant monies (from industry related sources): GlaxoSmithKline clinical research supportHeidi May: Grant monies (from industry related sources): GlaxoSmithKline clinical research supportTami Bair: Grant monies (from industry related sources): GlaxoSmithKline clinical research supportJeffrey Anderson: Grant monies (from industry related sources): GlaxoSmithKline clinical research supportNo Product/Research Disclosure InformationIntermountain Heart Institute, Salt Lake City, UT.