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Pooled Cohort Risk Equations for Cardiovascular Risk Prediction
Study Questions:
What is the predictive accuracy of the pooled cohort equations (PCEs) in a multiethnic cohort of contemporary US postmenopausal women?
Methods:
The investigators included women aged 50-79 years (n = 19,995) participating in the Women’s Health Initiative (WHI) with data on the risk equation variables at baseline and who met the guideline inclusion and exclusion criteria. They evaluated the accuracy of the PCE for predicting 10-year risk of atherosclerotic cardiovascular disease (ASCVD) and also the effects of time-varying treatments such as aspirin and statins, and ascertainment of additional ASCVD events by linkage with the Centers for Medicare and Medicaid Services (CMS) claims. Median follow-up was 10 years. The first ASCVD event was defined as the first occurrence of nonfatal myocardial infarction, coronary heart disease death, or fatal or nonfatal stroke. Observed rates of ASCVD were adjusted for variable follow-up time using Kaplan-Meier survival analysis.
Results:
Among the 19,995 women (mean [standard deviation] age, 64 [7.3] years; 8,305 [41.5%] white, 7,688 [38.5%] black, 3,491 [17.5%] Hispanic, 103 [0.5%] American Indian, 321 [1.6%] Asian/Pacific Islander, and 87 [0.4%] other/unknown), a total of 1,236 ASCVD events occurred in 10 years and were adjudicated through medical record review by WHI investigators. The WHI-adjudicated observed risks were lower than predicted. The observed (predicted) risks for baseline 10-year risk categories <5%, 5% to <7.5%, 7.5% to <10%, and 10% 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. Among women ≥65 years enrolled in Medicare, WHI-adjudicated risks were also lower than predicted, but 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. Similar results were seen across ethnic/racial groups. Overall, the equations discriminated risk well (C-statistic, 0.726; 95% confidence interval, 0.714-0.738).
Conclusions:
The authors concluded that without including surveillance for ASCVD events using CMS, observed risks in the WHI were lower than predicted by PCE, as noted in several other US cohorts, but risks were better aligned after including CMS events.
Perspective:
This study reports that without including surveillance for ASCVD events using CMS linkage, observed risks of ASCVD were lower than predicted in the WHI, as reported in other cohorts before. Furthermore, adjustment for time-dependent changes in statin or aspirin treatment during the study follow-up resulted in only small increases in observed risks. In contrast, there was a considerable impact of adding events that were identified by CMS surveillance, but not self-reported, and the observed risks became better aligned with predicted risks after including CMS events. Overall, the PCE models discriminated risk well and PCE appears to be a useful tool for CV risk prediction.
Keywords: Atherosclerosis, Aspirin, Centers for Medicare and Medicaid Services, U.S., Dyslipidemias, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Medicare, Myocardial Infarction, Myocardial Ischemia, Postmenopause, Primary Prevention, Risk Assessment, Risk Factors, Stroke, Women
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