Subclinical atherosclerosis measures for cardiovascular prediction in CKD

Abstract

Whether inclusion of the coronary artery calcium score improves cardiovascular risk prediction in individuals with CKD, a population with unique calcium-phosphate homeostasis, is unknown. Among 6553 participants ages 45-84 years without prior cardiovascular disease in the Multi-Ethnic Study of Atherosclerosis, coronary artery calcium score was assessed for cardiovascular risk prediction beyond the Framingham predictors in those with (n=1284) and without CKD and contrasted with carotid intima-media thickness and ankle-brachial index (two other measures of subclinical atherosclerosis). During a median follow-up of 8.4 years, 650 cardiovascular events (coronary heart disease, stroke, heart failure, and peripheral artery disease) occurred (236 events in subjects with CKD). In Cox proportional hazards models adjusted for Framingham predictors, each subclinical measure was independently associated with cardiovascular outcomes, with larger adjusted hazard ratios (HRs; per 1 SD) for coronary artery calcium score than carotid intima-media thickness or ankle-brachial index in subjects without and with CKD (HR, 1.69; 95% confidence interval [95% CI], 1.45 to 1.97 versus HR, 1.12; 95% CI, 1.00 to 1.25 and HR, 1.20; 95% CI, 1.08 to 1.32, respectively). Compared with inclusion of carotid intima-media thickness or ankle-brachial index, inclusion of the coronary artery calcium score led to greater increases in C statistic for predicting cardiovascular disease and net reclassification improvement. Coronary artery calcium score performed best for the prediction of coronary heart disease and heart failure, regardless of CKD status. In conclusion, each measure improved cardiovascular risk prediction in subjects with CKD, with the greatest improvement observed with coronary artery calcium score.

Keywords: CKD; arteriosclerosis; cardiovascular disease; coronary calcification.

Figure 1.

Adjusted incidence rate of CVD in participants with and without CKD according to CAC, IMT, and ABI and their distributions. The solid lines (red, CKD; blue, non-CKD) show estimated incidence rates of CVD (per 1000 person-years) and 95% CIs (whiskers and shaded area) with spline (knots at thresholds defining quartiles) for (A) CAC, (B) IMT, and (C) ABI. The incidence rate was adjusted to mean age, men, and whites, and the plot was truncated at 0.5th and 99.5th percentiles of each marker. The dashed lines (red, CKD; blue, non-CKD) show the distribution of each subclinical measure on the basis of kernel density estimate.