Circulating osteoprotegerin and progression of coronary artery calcification in patients with chronic kidney disease: the KoreaN Cohort Study for Outcome in Patients With Chronic Kidney Disease (KNOW-CKD).

Background: Coronary artery calcification (CAC) is a surrogate of cardiovascular events in patients with chronic kidney disease (CKD). To establish the role of circulating osteoprotegerin (OPG) as a cardiovascular biomarker in patients with CKD, we investigated whether an increase in serum OPG levels is associated with the risk of CAC progression.

Methods: A total of 1,130 patients with CKD stage 1 to predialysis 5 were divided into quartiles according to serum OPG levels (Q1 to Q4). The coronary artery calcium score (CACS) was assessed at baseline and at the 4-year follow-up visit. CAC progression was defined as an increase in the CACS of more than 200 Agatston units over 4 years.

Results: Serum OPG levels were positively correlated with the CACS at baseline (R = 0.240, p < 0.001) and at the 4-year follow-up visit (R = 0.280, p < 0.001) as well as with changes in the CACS for 4 years (R = 0.270, p < 0.001) based on scatter plot analysis. Binary logistic regression analysis demonstrated that the risk of CAC progression was significantly increased in Q4 compared with Q1 (adjusted odds ratio, 3.706; 95% confidence interval, 1.154-11.902). Penalized spline curve analysis revealed a linear association between serum OPG levels and the risk of CAC progression.

Conclusion: An increase in circulating OPG levels was associated with the risk of CAC progression in patients with predialysis CKD.