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Original Investigation
November 8, 2017

Coronary Artery Calcium Score for Long-term Risk Classification in Individuals With Type 2 Diabetes and Metabolic Syndrome From the Multi-Ethnic Study of Atherosclerosis

Author Affiliations
  • 1Division of Cardiology, Department of Medicine, University of California, Irvine
  • 2Susan Samueli Center for Integrative Medicine, University of California, Irvine
  • 3Department of Epidemiology, UCLA (University of California, Los Angeles), Los Angeles
  • 4Los Angeles Biomedical Research Institute, Harbor-UCLA Medical Center, Los Angeles, California
  • 5Center for Prevention and Wellness Research, Baptist Health Medical Group, Miami Beach, Florida
  • 6Ciccarone Center for the Prevention of Heart Disease, Johns Hopkins University, Baltimore, Maryland
  • 7Department of Epidemiology and Prevention, Wake Forest University School of Medicine, Winston–Salem, North Carolina
JAMA Cardiol. Published online November 8, 2017. doi:10.1001/jamacardio.2017.4191
Key Points

Question  What is the long-term clinical utility of coronary artery calcium scores for cardiovascular disease prognostication in those with established metabolic syndrome and type 2 diabetes in a multiethnic population?

Findings  Coronary artery calcium scores had significant long-term (>10 years) value in prognosticating cardiovascular disease in patients with metabolic syndrome and diabetes. A coronary artery calcium score of 0 was associated with low cardiovascular disease risk independent of diabetes duration, insulin use, or glycemic control.

Meaning  Assessment of subclinical disease using coronary artery calcium scores may have robust long-term value in prognosticating cardiovascular disease even in those who had diabetes for more than 10 years from the time of coronary artery calcium scoring.

Abstract

Importance  Although the risk of type 2 diabetes is considered to be equivalent to coronary heart disease (CHD) risk, there is considerable heterogeneity among individuals for CHD and atherosclerotic cardiovascular disease (ASCVD) risk. It is not known whether coronary artery calcium (CAC) assessment at baseline in individuals with established metabolic syndrome (MetS) or diabetes identifies CHD and ASCVD prognostic indicators during a long follow-up period.

Objective  To compare improvement in long-term prognostication of incident CHD and ASCVD using CAC scores among those with diabetes, MetS, or neither condition.

Design, Setting, and Participants  This study included participants from the Multi-Ethnic Study of Atherosclerosis (MESA), a prospective cohort study of 6814 males and females aged 45 to 84 years without known CVD from 4 race/ethnicity groups (white [38.5%], African American [27.5%], Hispanic [22.1%], and Chinese [11.9%]) recruited from 6 US communities from July 2000 through August 2002. Follow-up for each participant extended to the first occurrence of an incident event, other death, loss to follow-up, or the last follow-up call through December 31, 2013. Data analysis was performed from June 1, 2016, to September 12, 2017. Cox proportional hazards regression models were used to estimate hazard ratios (HRs). Area under the receiver operator characteristic curve and net reclassification improvement were used to compare incremental contributions of CAC score when added to the Framingham risk score, ethnicity/race, and socioeconomic status.

Main Outcomes and Measures  CHD events, including myocardial infarction, resuscitated cardiac arrest, or CHD death.

Results  Of 6814 MESA participants, 6751 had complete risk factor and follow-up data and were included in this study (mean [SD] age, 62.2 [10.2] years; 3186 [47.2%] male). A total of 881 (13.0%) had diabetes, 1738 (25.7%) had MetS, and 4132 (61.2%) had neither condition. After 11.1 mean years of follow-up, CHD events occurred in 84 participants with diabetes (135 ASCVD events), 115 with MetS (175 ASCVD events), and 157 with neither (250 ASCVD events). The CAC score was independently associated with incident CHD in multivariable analyses in those with diabetes (HR, 1.30; 95% CI, 1.19-1.43), MetS (HR, 1.30; 95% CI, 1.20-1.41), and neither condition (HR, 1.37; 95% CI, 1.27-1.47). For incident CHD, net reclassification improvement with addition of CAC score was 0.23 (95% CI, 0.10-0.37) in those with diabetes, 0.22 (95% CI, 0.09-0.35) in those with MetS, and 0.25 (95% CI, 0.15-0.35) in those with neither condition. The CAC score was also a prognostic indicator of CHD and ASCVD after controlling for diabetes duration of 10 years or longer at baseline, insulin use, and glycemic control.

Conclusions and Relevance  In a large multiethnic cohort, the addition of CAC score to global risk assessment was associated with significantly improved risk classification in those with MetS and diabetes, even if diabetes duration was longer than a decade, suggesting a role for the CAC score in risk assessment in such patients.

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