Relationship of Estimated GFR and Coronary Artery Calcification in the CRIC (Chronic Renal Insufficiency Cohort) Study

Background: Coronary artery calcification (CAC) is associated with increased mortality risk in the general population. Although individuals with chronic kidney disease (CKD) are at markedly increased mortality risk, the incidence, prevalence, and prognosis of CAC in CKD are not well understood. Study Design: Cross-sectional observational study. Setting & Participants: Analysis of 1,908 participants who underwent coronary calcium scanning as part of the multiethnic CRIC (Chronic Renal Insufficiency Cohort) Study. Predictor: Estimated glomerular filtration rate (eGFR) computed using the Modification of Diet in Renal Disease (MDRD) Study equation, stratified by race, sex, and diabetic status. eGFR was treated as a continuous and a categorical variable compared with the reference value of >60 mL/min/1.73 m(2). Measurements: CAC detected using computed tomography (CT) using either an Imatron C-300 electron beam computed tomography (CT) scanner or multidetector CT scanner. CAC was computed using Agatston score as a categorical variable. Analyses were performed using ordinal logistic regression. Results: We found a strong and graded relationship between lower eGFR and increasing CAC. In unadjusted models, ORs increased from 1.68 (95% CI, 1.23-2.31) for eGFR of 50-59 mL/min/1.73 m(2) to 2.82 (95% CI, 2.06-3.85) for eGFR <30 mL/min/1.73 m(2). Multivariable adjustment only partially attenuated the results (OR, 1.53; 95% CI, 1.07-2.20) for eGFR <30 mL/min/1.73 m(2). Limitations: Use of eGFR rather than measured GFR. Conclusions: We showed a graded relationship between severity of CKD and CAC independent of traditional risk factors. These findings support recent guidelines that state that if vascular calcification is present, it should be considered as a complementary component to be included in the decision making required for individualizing CKD treatment. Am J Kidney Dis. 58(4): 519-526. (C) 2011 by the National Kidney Foundation, Inc.