Variability of red blood cell size predicts all-cause mortality, but not progression to dialysis, in patients with chronic kidney disease: A 13-year pre-ESRD registry-based cohort

Abstract

BackgroundPrognostic role of red blood cell distribution width (RDW) in patients with chronic kidney disease (CKD) is unclear. Little evidence provides a comprehensive predictive analysis considering both baseline values and longitudinal trajectories of RDW along with mean corpuscular volume (MCV). MethodsWe conducted a comprehensive risk assessment of RDW and MCV in a registry-based cohort of 4621 patients with CKD (age, 20–90 y) receiving multidisciplinary care during 2003 to 2015. Both baseline and longitudinal trajectories of RDW and MCV were modeled as predictors for end-stage renal disease (ESRD) and mortality by using multiple Cox proportional hazards regression models, incorporating time-varying covariates and adjustments for imperative confounding variables. ResultsFully adjusted hazard ratio (HR; 95% CI) of progression to ESRD for each unit increase in RDW and MCV at baseline was 0.97 (0.93–1.02) and 1.00 (0.99–1.01), respectively. Longitudinally, neither RDW nor MCV trajectory was associated with progression to ESRD. For all-cause mortality, fully adjusted HRs (95%CI) were 1.09 (1.04–1.14) for each percent increase in RDW with a linear dose–response relationship and 1.95 (1.47–2.59) for a stable-high RDW trajectory compared with normal RDW trajectory. The effects of RDW on mortality were further augmented in patients with concomitantly high MCV status. Incorporating point-of-care RDW significantly improves the discrimination performance quantified using Harrell C statistics into the existing CKD mortality predictive equation (from 0.770 to 0.784, P = .018). ConclusionsWe support the clinical utility of RDW in predicting all-cause mortality among patients with CKD. The mechanism underlying our findings is critical for CKD risk assessment and management, particularly from malnutrition, inflammation, and atherosclerosis perspectives.