Low white blood cell count is independently associated with chronic kidney disease progression in the elderly: the CKD-ROUTE study.

Abstract

Elevated white blood cell (WBC) count is a well-known predictor of chronic kidney disease (CKD) progression. However, elderly patients commonly fail to develop a high WBC count in response to several diseased states and may instead present a low WBC count. Therefore, we hypothesized that low WBC count, in addition to high WBC count, is associated with CKD progression in the elderly. We conducted a prospective cohort study using 3-year follow-up data from the CKD Research of Outcomes in Treatment and Epidemiology study. In the present study, participants aged over 60years with pre-dialysis CKD stages G2-G5 were eligible. Patients were stratified into three groups according to WBC count using tertiles (T). The primary outcome was a composite of end-stage renal disease and a 50% reduction in estimated glomerular filtration rate. Data were analyzed using Cox proportional hazard models with adjustments for covariates. We enrolled 697 patients (males, 69%). The median WBC count was 6100cells/µl (T1, <5400, n= 222; T2, 5400-6900, n= 235; T3, ≥6900, n=240). During a median follow-up of 868days, the primary outcome was observed in 170 patients, whereas 54 patients died. T1 and T3 had significantly higher hazard ratios (HR) than T2 (T1, HR 1.69, 95% confidence interval 1.14-2.51; T3, HR 1.63, 95% confidence interval 1.10-2.41). Moreover, T1 had a significantly higher adjusted HR (1.54, 95% confidence interval 1.00-2.37). Low WBC count is independently associated with CKD progression in the elderly.