Normal white blood cell counts predict long-term mortality of hemodialysis patients.

Purpose: It is unclear whether normal white blood cell (WBC) counts are predictive of subsequent mortality in hemodialysis patients.

Methods: All patients aged 17 years or more, who initiated hemodialysis at a tertiary Hospital from January 2000 to August 2017 with a dialysis vintage of greater than 90 days and normal median WBC count of their first dialysis year were included in the study. They were followed until they died, transferred to other dialysis facilities, switched to peritoneal dialysis, received a renal transplant or reached the end of the study (August 31, 2018). Cox regression was used to estimate hazard ratios for mortality of tertiles of WBC counts, adjusting for baseline demographic, clinical and laboratory variables.

Results: 611 patients [median (interquartile range) age 65.2 (53.3-72.6) years, 62.4% male] were studied. During a median follow-up of 3.9 (1.6-7.2) years, 270 participants died. Patients in the mid- (6.25-7.73 × 10/μL, n = 203) and top-tertile (7.73-10.50 × 10/μL, n = 203) of normal WBC counts had significantly higher mortality than patients in the bottom-tertile (3.50-6.25 × 10/μL, n = 205). The adjusted hazard ratio for mortality relative to the bottom-tertile was 1.54, 95% confidence interval (CI) 1.05-2.25 and 2.20, 95% CI 1.46-3.32, for the mid- and top-tertiles, respectively.

Conclusions: In hemodialysis patients, higher WBC count within the normal range is associated with increased long-term mortality. This finding is described for the first time and provides further insight into the clinical significance of a "normal" WBC count result in dialysis patients.