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.

BACKGROUND

Prognostic 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).

METHODS

We 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.

RESULTS

Fully 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).

CONCLUSIONS

We 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.