Risk Prediction Models for Cardiovascular Events in Black Adults
Is it necessary to produce a new risk prediction model for cardiovascular disease (CVD) incidence in black adults, incorporating standard risk factors, biomarkers, and subclinical disease, rather than using the American College of Cardiology/American Heart Association (ACC/AHA) CVD Pooled Cohort risk equation?
The Jackson Heart Study (JHS) is a longitudinal community-based study of 5,301 black adults in Jackson, Mississippi. Study dates included first visit (between 2000 and 2004) to maximal follow-up of December 31, 2011. Measurements included standard risk factors, estimated glomerular filtration rate, antihypertensive therapy, diabetes mellitus, and smoking; 10 blood biomarkers; and subclinical disease measures, including ankle-brachial index (ABI), carotid intimal-medial thickness, and echocardiographic left ventricular mass and systolic dysfunction. Incident CVD event was defined as the first occurrence of myocardial infarction, coronary heart disease death, congestive heart failure (CHF), stroke, incident angina, or intermittent claudication. Model performance was compared with the ACC/AHA CVD risk algorithm and the Framingham Risk Score (FHS) refitted to the JHS data and evaluated in the Atherosclerosis Risk in Communities (ARIC) and Multi-Ethnic Study of Atherosclerosis (MESA) cohorts.
The study cohort comprised 3,689 participants with mean (standard deviation) age at baseline of 53 (11) years, and 64.8% (n = 2,390) were female. Over a median of 9.1 years, 270 participants (166 women) experienced a first CVD event. A simple combination of standard CVD risk factors, B-type natriuretic peptide (BNP), and ABI yielded modest improvement over a model without BNP and ABI (C statistic, 0.79; 95% confidence interval [CI], 0.75-0.83 [relative integrated discrimination improvement, 0.22; 95% CI, 0.15-0.30]). However, the reclassification improvement was not substantially different between this model and the ACC/AHA CVD Pooled Cohort risk equations or the FHS. The models discriminated reasonably well in the ARIC and MESA data (C statistic range, 0.70-0.77).
The findings using the JHS data in the present study are valuable because they confirm that current FHS and ACC/AHA risk algorithms work well in black individuals and are not easily improved upon. A unique risk calculator for black adults may not be necessary.
That the BNP and ABI did not add to the predictive value is a bit surprising considering that compared with white adults, blacks have a higher risk of CHF and a twofold incidence of strokes and peripheral vascular disease. The lack of value of serum biomarkers is similar to FHS and MESA. The value of coronary artery calcium scoring as demonstrated in MESA was not evaluated in the JHS.
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