Objective: Zinc (Zn) plays an important role in immune function. Several studies have identified an association between a Zn deficiency and infection. Infectious diseases are major complications of chronic kidney disease (CKD). We investigated whether serum Zn concentrations are associated with risk of infection in patients with advanced CKD.
Design and methods: We retrospectively analyzed data from 299 patients with CKD whose serum Zn values were measured to evaluate anemia between January 2013 and December 2016. Among them, 9 who were supplemented with Zn and 67 who had started urgent dialysis at the time of measurement were excluded. We analyzed infection events, length of infection-related hospitalization and infection-related and all-cause mortality in the remaining 223 patients during a median follow-up of 36 months. We assigned the patients to groups with low or high Zn values (≤50 and >50 μg/dL, respectively) based on a median value of 50 μg/dL. Data were analyzed using Kaplan-Meier curves and Cox hazards models.
Results: During a median follow-up of 36 months, 40 patients were hospitalized with infections. The rate of infection-related and long-term hospitalization (>10 days) due to infection was higher for patients with low, than high, Zn values (23.3% vs. 12.6%; P = .042 and 26.2% vs. 12.4%; P = .007, respectively). After adjustment in Cox hazards models, low serum Zn values remained an independent risk factor for infection-related hospitalization (Hazard ratio [HR], 1.93; 95% confidence interval [CI], 1.01-3.71; P = .048), especially for patients on proton pump inhibitor (PPI) medications (HR, 2.66, 95%; CI, 1.22-5.81; P = .014).
Conclusion: Patients with advanced CKD accompanied by low serum Zn concentration, and particularly those medicated with PPI, are at high risk of infection-related hospitalization, which results in long-term hospitalization.
Copyright © 2020 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.