Type 2 diabetes mellitus modifies the relationship between coronary artery calcification and adverse kidney outcome in patients with chronic kidney disease: the findings from KNOW-CKD.

Background: Kidney function declines faster in patients with type 2 diabetes mellitus (T2DM) than in those without, and coronary artery calcification is a risk factor for adverse kidney outcomes. Thus, we examined whether T2DM modified the relationship between coronary artery calcification and chronic kidney disease (CKD) progression.

Methods: Among 2067 participants from the KoreaN Cohort Study for Outcome in Patients With CKD, the main exposures analyzed were T2DM and coronary artery calcification. The primary outcome was CKD progression, which was a composite of > 50% decline in estimated glomerular filtration rate (eGFR) or kidney failure requiring kidney replacement therapy. A multivariable cause-specific hazard model was used to determine the association between the main exposures and the primary outcome.

Results: During 8633 person-years of follow-up, the primary outcome occurred in 565 (27.3%) participants. After adjusting for confounding factors, T2DM and coronary artery calcification score > 0 were associated with 2.03- and 1.51-fold increased risks of CKD progression, respectively. T2DM and coronary artery calcification showed a significant interaction in terms of the primary outcome. In patients with T2DM, coronary artery calcification score > 0 was associated with a significantly higher risk of CKD progression compared with coronary artery calcification score = 0. However, the significant association of coronary artery calcification score > 0 versus coronary artery calcification score = 0 was lost in patients without T2DM. The slope of eGFR decline was steeper in patients with T2DM and coronary artery calcification score > 0 than in those with T2DM or coronary artery calcification score > 0 alone.

Conclusions: Coronary artery calcification is more strongly associated with the risk of CKD progression in patients with T2DM than in those without. Therefore, the clinical implications of coronary artery calcification vary depending on the presence of T2DM.