The predictive role of serum calprotectin on mortality in hemodialysis patients with high phosphoremia

BACKGROUND: The inflammatory mediator calprotectin (CPT, myeloid-related protein 8/14) is known as an endogenous ligand contributing to pathophysiology in inflammatory diseases. Serum CPT reportedly became a potential biomarker in these conditions, though there is no report predicting the prognosis in hemodialysis patients. The aim of this study is to investigate the predictive role of serum CPT on mortality in hemodialysis patients. METHODS: We conducted a multicenter, observational cohort study of 388 Japanese subjects undergoing hemodialysis. Serum CPT were measured using an ELISA. The potential associations between serum CPT and clinical variables were cross-sectionally examined. Multivariate Cox regression was used to estimate the association between serum CPT, high-sensitivity C reactive protein (hs-CRP), white blood cell (WBC) count and mortality. Median follow-up was 6.6 years. RESULTS: The median CPT level was 6108 ng/ml (median in healthy subjects, 2800) at baseline. Serum CPT positively correlated with WBC count (ρ = 0.54, P < 0.001) and hs-CRP values (ρ = 0.35, P < 0.001). In multivariate analysis, hs-CRP was an independent predictor of all-cause mortality after adjusting confounding factors (middle vs. low: hazard ratio HR 2.09, 95% confidence interval CI 1.23-3.66; high vs. low: 2.47, 1.40-4.47). In the analysis by stratum of phosphate levels, elevated CPT levels were significantly associated with all-cause mortality in the highest tertile (18.1; 3.15-345.9) among the high-phosphate group, but not among the low-phosphate group. CONCLUSIONS: Serum CPT would become a potential predictive marker on mortality in hemodialysis patients with high-phosphate levels.