Fetuin-A as a risk factor for mortality in hemodialysis patients
OBJECTIVES: Fetuin A, a circulating inhibitor of calcification, is regulated as a negative acute-phase protein. However, its relationship with outcomes of patients undergoing hemodialysis has not been well evaluated. The aim of our study was to determine the association between fetuin-A and some factors of metabolism and their impact on all-cause mortality in hemodialysis patients.
PATIENTS AND METHODS: The study comprised 106 hemodialysis patients, 45 of whom were women. Levels of serum fetuin-A were measured by ELISA and serum intact parathyroid hormone (iPTH) by immunoassay in each patient. Serum Ca, serum P, Ca × P product, alkaline phosphatase, cholesterol, triglycerides, bicarbonate, albumin, homocysteine and C-reactive protein (CRP) were measured using routine laboratory methods. Survival rates were analyzed using Kaplan–Meier survival curves. A Cox regression model was used to access the possible influence of variables on all-cause mortality.
RESULTS: The mean value of fetuin-A was 15.3 ± 3.8 g/l, range 5.5–23.7 g/l. Significant correlations were found between serum fetuin-A and serum iPTH (r = –0.239; P = 0.014), alkaline phosphatase (r = –0.240; P = 0.013), triglycerides (r = +0.236; P = 0.015) and serum albumin level (r = +0.286; P = 0.003). Patients were followed-up prospectively from the first day of the laboratory measurement for a maximum of 752 days or until death. A total of 24 patients died. Surviving patients had higher levels of fetuin-A (P = 0.005), serum cholesterol (P = 0.0001), triglycerides (P = 0.004), albumin (P = 0.0001) and homocysteine (P = 0.028). Kaplan–Meier survival analysis showed higher mortality in the first tertile of fetuin-A than in the third tertile (P = 0.0297). In our patients, serum Ca (P = 0.025), serum P (P = 0.040) and the Ca × P product (P = 0.039) were found to be predictors of mortality in the Cox multivariable regression model.
CONCLUSIONS: In patients undergoing hemodialysis, lower fetuin-A levels are associated with higher mortality. Metabolism of Ca and P were directly associated with higher mortality.