Serum Calcification Propensity and Fetuin-A: Biomarkers of Cardiovascular Disease in Kidney Transplant Recipients

Abstract

Background: “T50,” shortened transformation time from primary to secondary calciprotein particles may reflect deranged mineral metabolism predisposing to vascular calcification and cardiovascular disease (CVD). The glycoprotein fetuin-A is a major T50 determinant. Methods: The Folic Acid For Vascular Outcome Prevention In Transplantation (FAVORIT) cohort is a completed, large, multiethnic controlled clinical trial cohort of chronic, stable kidney transplant recipients (KTRs). We conducted a longitudinal case-cohort analysis using a randomly selected subcohort of patients, and all individual cases who developed CVD. Serum T50 and fetuin-A were determined in this total of n = 685 FAVORIT trial participants at randomization. Results: During a median surveillance of 2.18-years, 311 incident or recurrent CVD events occurred. Shorter T50 (minutes) or reduced fetuin-A concentrations (g/L) were associated with CVD after adjustment for treatment assignment, systolic blood pressure, age, sex, race, preexisting CVD and diabetes, smoking, body mass index, total cholesterol/HDL cholesterol, kidney allograft vintage and type, calcineurin inhibitor, or lipid-lowering drug use, estimated glomerular filtration rate, and urinary albumin/creatinine: tertile 1 (lowest) to tertile 3 (highest) comparisons, T50, (hazard ratio [HR] 1.86; 95% CI 1.20–2.89); fetuin-A, (HR 2.25; 95% CI 1.38–3.69). Elevated high sensitivity c-reactive protein (hsCRP) was an effect modifier of both these associations. Conclusions: Shortened T50, as well as reduced fetuin-A levels, ostensible promoters of vascular calcification, remained associated with greater risk for CVD outcomes, after adjustment for major CVD risk factors, measures of kidney function and damage, and KTR clinical characteristics and demographics, in a large, multiethnic cohort of long-term KTRs. Increased hsCRP was an effect modifier of these CVD risk associations.