Red blood cell distribution width and mortality and hospitalizations in peritoneal dialysis patients

Abstract

Background: Red blood cell distribution width (RDW) is found to be associated with different types of anemia and has recently been studied as a prognostic marker of mortality in hemodialysis patients. However, the relationship of RDW with mortality and hospitalization rate in peritoneal dialysis (PD) patients is less known.

Methods: Among 14 323 incident PD patients between 2007 and 2011 in the USA, we examined the relationship of baseline and time-varying RDW with the risk of mortality and time to first hospitalization using adjusted Cox models. In addition, we examined the relationship of baseline RDW and hospitalization rate using an adjusted negative-binomial regression model. Sensitivity analyses included competing risk models and subgroup analyses.

Results: The study population comprised patients 56 ± 16 years of age, including 43% females, 23% African Americans and 62% diabetics, with a mean RDW of 15.3 ± 1.6%. In models adjusted for clinical characteristics and laboratory parameters, RDW exhibited an incremental relationship with the mortality risk, where RDW ≥16.5% had a 40% and 69% higher risk of death in baseline and time-varying analyses, respectively, compared with an RDW of 14.5-15.5%. Moreover, higher baseline RDW ≥16.5% was also associated with a higher risk of time to first hospitalization {hazard ratio 1.22 [95% confidence interval (CI) 1.14-1.29]} and a higher rate of hospitalizations [incidence rate ratio 1.16 (95% CI 1.09-1.23)]. These results were consistent across numerous sensitivity analyses.

Conclusions: Higher RDW is associated with a higher risk of mortality and hospitalizations among incident PD patients. Further studies are needed to examine the mechanism behind RDW and adverse outcomes.

Keywords: hospitalization; mortality; peritoneal dialysis; red blood cell distribution width.