BACKGROUND AND AIMS:Coronary artery calcification (CAC) is common among patients with chronic kidney disease (CKD) and predicts the risk for cardiovascular disease (CVD). We examined the associations of novel risk factors with CAC progression among patients with CKD. METHODS:Among 1123 CKD patients in the Chronic Renal Insufficiency Cohort (CRIC) Study, CAC was measured in Agatston units at baseline and a follow-up visit using electron beam computed tomography or multidetector computed tomography. RESULTS:Over an average 3.3-year follow-up, 109 (25.1%) participants without CAC at baseline had incident CAC and 124 (18.0%) participants with CAC at baseline had CAC progression, defined as an annual increase of ≥100 Agatston units. After adjustment for established atherosclerotic risk factors, several novel risk factors were associated with changes in CAC over follow-up. Changes in square root transformed CAC score associated with 1 SD greater level of risk factors were -0.20 (95% confidence interval, -0.31 to -0.10; p < 0.001) for estimated glomerular filtration rate, 0.14 (0.02-0.25; p = 0.02) for 24-h urine albumin, 0.25 (0.15-0.34; p < 0.001) for cystatin C, -0.17 (-0.27 to -0.07; p < 0.001) for serum calcium, 0.14 (0.03-0.24; p = 0.009) for serum phosphate, 0.24 (0.14-0.33; p < 0.001) for fibroblast growth factor-23, 0.13 (0.04-0.23; p = 0.007) for total parathyroid hormone, 0.17 (0.07-0.27; p < 0.001) for interleukin-6, and 0.12 (0.02-0.22; p = 0.02) for tumor necrosis factor-α. CONCLUSIONS:Reduced kidney function, calcium and phosphate metabolism disorders, and inflammation, independent of established CVD risk factors, may progress CAC among CKD patients.