In adults without CVD, the MESA score, including coronary artery calcium, predicted 10-y risk for CHD events

Question In adults without cardiovascular disease (CVD), how well does a risk score based on coronary artery calcium (CAC) and traditional CV risk factors predict 10-year risk for coronary heart disease (CHD) events? Methods Design 3 prospective cohort studies, 1 for derivation (Multi-Ethnic Study of Atherosclerosis [MESA]) and 2 for validation (Heinz Nixdorf Recall [HNR] study and Dallas Heart Study [DHS]). Median follow-up was 10.2 years in the MESA, 9.3 years in the DHS, and 10.4 years in the HNR study. Setting 6 communities in the USA (MESA); 3 cities in Germany (HNR study); and Dallas County, Texas, USA (DHS). Participants The derivation cohort comprised 6726 participants 45 to 84 years of age (mean age 62 y, 53% women) who self-identified as white, African American, Hispanic, or Chinese. The validation cohorts comprised 3692 Caucasian participants 45 to 75 years of age (mean age 60 y, 54% women) in the HNR study and 1080 Caucasian, African American, or Hispanic participants 45 to 65 years of age (mean age 53 y, 57% women) in the DHS. Participants in all cohorts had no CVD at baseline. Description of prediction guide The MESA risk score included traditional risk factors and CAC, with 12 variables that were continuous (age, total and high-density lipoprotein cholesterol levels, systolic blood pressure, and Agatston CAC score), categorical (ethnicity), or dichotomous (sex, smoking status, family history of heart attack, diabetes, use of lipid-lowering drugs, and use of antihypertensive drugs). A calculator for the risk score is available (www.mesa-nhlbi.org/CAC-Tools.aspx). Outcome Composite of CHD events including myocardial infarction, revascularization in patients with previous or concurrent adjudicated angina, resuscitated cardiac arrest, or fatal CHD. Main results Based on Kaplan-Meier estimates, 6.5% of participants in MESA, 7.5% in HNR, and 5.5% in DHS had CHD events at 10 years. In the derivation cohort, adding CAC to traditional risk factors improved the area under the receiver-operating characteristic curve (0.81 vs 0.76, P <0.001). The C-statistics are shown in the Table. Mean predicted 10-year CHD risk was greater in participants who had CHD events than in those who did not have events across all cohorts (risk difference 4.6% to 5.3% for the score based on traditional risk factors and 7.8% to 9.5% for the score based on traditional risk factors with CAC). Conclusion In adults without cardiovascular disease, the MESA score based on traditional risk factors and coronary artery calcium improved risk prediction for coronary heart disease events at 10 years compared with traditional risk factors alone. MESA risk score, based on traditional risk factors with CAC, for predicting coronary heart disease events at 10 years in participants with no CVD at baseline* Risk score Cohorts C statistics (95% CI) Traditional risk factors MESA (derivation) 0.750 (0.729 to 0.771) HNR (validation) 0.720 (0.693 to 0.747) DHS (validation) 0.782 (0.730 to 0.833) Traditional risk factors + CAC MESA (derivation) 0.800 (0.781 to 0.820) HNR (validation) 0.779 (0.754 to 0.805) DHS (validation) 0.816 (0.770 to 0.862) *CAC = coronary artery calcium; CVD = cardiovascular disease; DHS = Dallas Heart Study; HNR = Heinz Nixdorf Recall; MESA = Multi-Ethnic Study of Atherosclerosis. 95% CIs provided by author. Commentary In the MESA population, a 2012 study found that CAC provided better discrimination and risk reclassification than other individual risk factors (1). The study by McClelland and colleagues continues that work with the MESA score, an easily accessible new risk assessment tool for predicting CHD in 4 racial groups, adding CAC as a direct measure of coronary plaque burden to 11 risk factors. The new MESA score with CAC is an important tool for calculating CHD risk and informing discussions with concerned or skeptical adult patients about lifelong use of lipid-lowering agents. It includes the same risk factors as the American College of Cardiology/American Heart Association (ACC/AHA) equation; evaluates the score in a broader range of ethnic groups; and, of note, includes CAC as a measure of lifelong risk factor exposure for atherosclerotic disease. This improves CHD discrimination and risk reclassification in the 3 cohorts studied. In contrast to the ACC/AHA risk calculator, the predicted CHD outcome of the MESA tool does not include stroke. The recent BIOIMAGE study categorized almost 6000 patients 60 to 80 years of age by CAC score tertiles and carotid plaque burden (cPB) and found that either measure of the coronary or carotid system predicted a composite outcome of myocardial infarction, CV death, or ischemic stroke equally over 3 years (2). This suggests that CAC or cPB may equally predict short-term adverse atherosclerotic CVD outcomes. Another MESA study found that 41% of patients classified as needing statin therapy using the 2013 ACC/AHA risk equation had CAC scores of 0, decreasing their 10-year atherosclerotic CVD risk to 5.2% and thus nullifying the need for statin therapy (3). By including CAC for patients who have this information available, the new MESA CHD score should enhance risk assessment and classification of the 10-year ACC/AHA ASCVD risk calculator for life-long statin use.