Do Pooled Cohort Equations Overestimate ASCVD Risk?

Without including surveillance for atherosclerotic cardiovascular disease (ASCVD) events using the Centers for Medicare and Medicaid Services (CMS), observed risks may be lower than predicted by pooled cohort equations,according to a study published July 23 in JAMA Internal Medicine.

Samia Mora, MD, MHS, FACC, et al., sought to evaluate the predictive accuracy of the pooled cohort equations in the Women's Health Initiative (WHI), a multi-ethnic cohort of contemporary U.S. post-menopausal women, and looked at a diverse group of 19,995 women aged 50 to 79.

Results showed a total of 1,236 ASCVD events occurred in 10 years. The authors found that the observed (predicted) risks for baseline 10-year risk categories less than 5 percent, 5 percent to less than 7.5 percent, 7.5 percent to less than 10 percent, and 10 percent or more were 1.7 (2.8), 4.4 (6.2), 5.3 (8.7) and 12.4 (18.2), respectively. Small changes were noted after adjusting for time-dependent changes in statin and aspirin use.

Additionally, the authors found that while WHI-adjudicated risks were lower than predicted among women 65 years or older enrolled in Medicare, observed (predicted) risks became aligned after including events ascertained by linkage with CMS for additional surveillance for events: 3.8 (4.3), 7.1 (6.4), 8.3 (8.7) and 18.9 (18.7), respectively. They add that similar results were seen across ethnic and racial groups.

In an accompanying editorial comment, Gregory D. Curfman, MD, FACC, notes that "the central message of the study by Mora, et al., is that accurate measurement of ASCVD risk in populations depends on comprehensive surveillance of events, but whether this provides a complete explanation of the overestimation of risk by the pooled cohort equation remains uncertain."

Clinical Topics: Dyslipidemia, Nonstatins, Novel Agents, Statins

Keywords: Hydroxymethylglutaryl-CoA Reductase Inhibitors, Aspirin, Centers for Medicare and Medicaid Services (U.S.), Postmenopause, Medicaid, Atherosclerosis, Medicare Assignment, Risk, Cohort Studies


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