Serum T50 Test Reflects CAC Progression Risk in CKD

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A new serum test of calcification propensity provides useful information on the severity and progression of coronary artery calcification (CAC) in patients with chronic kidney disease, reports the American Journal of Kidney Diseases.

The prospective study included patients with stage 2 to 4 CKD, mean age 57.5 years, enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study. Serum calcification propensity was measured as the transformation time from primary to secondary calciprotein particles (T50), with lower T50 values reflecting a higher calcification propensity. The analysis included baseline samples from 1274 patients and follow-up samples (average 3 years) from 780 patients.

On baseline CT scans, 65% of patients had CAC. Median T50 value was 321 minutes. Lower T50 values (higher calcification propensity) were associated with a wide range of factors: non-Hispanic black race/ethnicity, history of cardiovascular disease and diabetes, higher blood pressure, and lower kidney function.

In multivariable-adjusted models, T50 was unrelated to the presence of CAC. However, among patients with prevalent CAC, lower T50 was linked to increased CAC severity: a 21% increase in severity per 1-standard deviation decrease in T50.

During follow-up, 20% of patients developed incident CAC while 19% had progression (annual increase of 100 Agatston units or more) of baseline CAC. On adjusted analysis, T50 was unrelated to the development of new CAC, but was significantly associated with CAC progression. For each 1-standard deviation in T50, the risk of CAC progression increased by 28%.

Coronary artery calcification is common in patients with CKD and is associated with increased cardiovascular risks. By evaluating the transformation from primary to secondary calciprotein particles, the T50 test might provide a useful marker of CAC and the associated risks.

This study finds that a lower serum T50, indicating increased calcification propensity, is associated with greater CAC severity and an increased risk of CAC progression in patients with CKD. The T50 test does not appear to reflect prevalent CAC. Noting that further studies are needed to establish causality, the investigators conclude, “These findings provide valuable insights into the development of calcification and atherosclerosis in patients with CKD and highlight potential pathways for risk stratification and therapeutic intervention” [Bundy JD, et al. Serum calcification propensity and coronary artery calcification among patients with CKD: The CRIC (Chronic Renal Insufficiency Cohort) Study. Am J Kidney Dis 2019; https://doi.org/10.1053/j.ajkd.2019.01.024].

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