White blood cell count predicts the odds of kidney function decline in a Chinese community-based population

BACKGROUND Inflammatory processes are very important in the development of kidney disease. Nevertheless, the association between white blood cell (WBC) count and the risk of renal dysfunction has not been well-established, especially in subjects without chronic kidney disease (CKD). Our study investigated the association between WBC count and kidney function decline in a Chinese community-based population with baseline estimated glomerular filtration rate (eGFR) ≥60 mL/min/1.73 m2. METHODS A total of 3768 subjects who were enrolled in an atherosclerosis cohort in Beijing were included in this study. EGFRs were calculated at baseline and follow-up using the CKD-EPI formula. The outcomes of this study were renal function decline (RFD) (a drop in eGFR stage along with a decline in eGFR of 25% or exceeding 5 mL/min/1.73 m2/year), rapid eGFR decline (an annual decrease in eGFR exceeding 3 mL/min/1.73 m2), and incident CKD (eGFR <60 min/1.73 m2 at follow-up). Multivariate logistic regression models were used to evaluate the associations between WBC count and each outcome. RESULTS On average, the subjects were 56.6 ± 8.5 years old, and 35.9% were male. Of the participants, 48.6% had hypertension and 17.4% had diabetes. The mean (SD) WBC count at baseline was 6.1 ± 1.5 × 109/L. The mean (SD) eGFR at baseline was 101.1 ± 10.6 mL/min/1.73 m2. After 2.3 years follow-up, the incidence rates of RFD, rapid eGFR decline and new CKD were 7.7, 20.9, and 0.8%, respectively. WBC count was significantly related to RFD, rapid eGFR decline and new CKD in the univariate analyses. Even after adjustment for demographic variables, comorbidities, medications and baseline eGFR, these associations remained. Moreover, similar trends in RFD were observed in nearly all subgroups stratified by each confounding variable. The increase in the odds of RFD associated with each 109/L increase in WBC count was significantly greater in subjects not undergoing treatment with lipid-lowering drugs than those not undergoing this treatment (P-interaction: 0.05). CONCLUSIONS In conclusion, elevated WBC count served as a predictor of the odds of kidney function decline in this population, which supports the hypothesis that systemic inflammation may serve as a risk factor for CKD development.