SAN DIEGO—Hemodialysis (HD) patients with higher red cell distribution width (RDW), a measure of red blood cell size and variability indicating iron-deficiency anemia, had greater risks of early mortality, according to a new study presented at Kidney Week. Whether RDW is a marker or an actual risk factor for mortality remains to be seen.

A team led by Tania Vashistha, MD, and Kamyar Kalantar-Zadeh, MD, MPH, PhD, nephrology faculty investigators at the University of California Irvine School of Medicine, examined all-cause mortality in 109,675 HD patients from a single organization from 2007–2011. Average patient age was 63 and 58% were diabetic, 44% were female, and 31% were African American.

Looking at RDW measurements in 5 ascending categories (less than 14.5%; 14.5% to less than 15.5%; 15.5% to less than 16.5%; 16.5% to less than 17.5%; and 17.5% and greater) the researchers discovered higher RDW was linearly associated with higher risk of mortality from all causes. The results held in models adjusted for factors such as comorbidities, malnutrition, and inflammation.

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These data suggest that RDW, which can reflect iron status, can be used as an important predictor of dialysis patient outcomes, according to investigators. Future studies need to confirm the findings and determine the mechanisms behind the association of RDW with mortality. Whether RDW can serve as a better iron metric and better predictor of survival in dialysis patients than conventional iron and anemia indices warrants additional studies, they stated.