Coronary artery calcification and mortality in diabetic patients with proteinuria

Vascular calcification is one of the mechanisms mediating the higher mortality risk associated with the hyperphosphatemia of chronic kidney disease. Though common, and often severe in non-dialyzed proteinuric diabetics, there are no studies on the prognostic significance of coronary artery calcification in early stage type 2 diabetic nephropathy. Here we determine this significance in 225 proteinuric diabetic patients (mean age 57 years, mean estimated glomerular filtration rate (eGFR) 52 ml/min per 1.73 m(2) and a median urine protein-creatinine ratio of 2.7). Coronary artery calcification, measured by electron beam computed tomography, was diagnosed in 86% of the patients, the severity of which correlated with older age, male gender, and white ethnicity. However, no association was found between eGFR, serum calcium, phosphorus, parathyroid hormone, or 25-hydroxy vitamin D. Over an average follow-up of 39 months, 54 patients died. A graded relationship between the severity of calcification and all-cause mortality was consistently demonstrated on both univariate and multivariate analyses. Patients in the highest quartile of calcification score had a 2.5-fold higher risk for death. Our results show the severity of coronary artery calcification early in the course of chronic kidney disease is an independent predictor of all-cause mortality. Additional studies need to determine whether altering the natural history of coronary artery calcification in early chronic kidney disease prolongs survival.