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Further Insight Into the Cardiovascular Risk Calculator | Journal Scan
Study Questions:
Does use of statins and coronary revascularization explain the difference between the assessment of cardiovascular risk using the American College of Cardiology (ACC)/American Heart Association (AHA) guidelines and observed event rates in the Women’s Health Study (WHS)?
Methods:
Data from the WHS were used for the present analysis. WHS is a nationwide cohort of US women who had no clinical diagnosis of cardiovascular disease (CVD), cancer, or other major illness at baseline. Women were ages 45-79 years of age at enrollment in 1992 to 1995. Measures of plasma lipids and other CVD risk factors were collected for a median of 10 years. The primary outcome of interest was atherosclerotic cardiovascular disease (ASCVD), which included myocardial infarction, stroke, or death due to cardiovascular cause.
Results:
A total of 27,542 women were included, of which 632 women experienced an ASCVD event during the follow-up. The predicted risk was 3.6% over 10 years compared with the actual observed risk of 2.2%. Predicted rates were higher than observed rates in most risk groups. Predicted to observed rates were 1.90 or higher in the groups with 0 to <5.0% and 5.0% to <7.5% risk, and were over 1.40 in the groups with 7.5% to <10.0% and 10.0% or higher risk. Rates of statin use and revascularizations increased over follow-up time and by risk group. Adjustment for intervention effects of statins and revascularization in addition to potential confounding by indications, predicted event rates remained higher than observed rates (1.80 or higher in the lower two risk groups and over 1.30 higher in the upper two risk groups). It was estimated that 60% more events would be required to match the numbers predicted using the pooled cohort equations.
Conclusions:
The authors concluded that statin use, revascularization procedures, and under ascertainment of events do not explain the discrepancy between observed rates of ASCVD in the WHS and those predicted by the ACC/AHA pooled cohort equations. Other explanations include changing patterns of risk within more contemporary populations.
Perspective:
Risk assessments are only as good as the cohorts upon which they were developed. Incongruities between observed and predicted risk may reflect the differences in cohorts. WHS is a predominately white middle-class cohort. Furthermore, most minorities and those with lower incomes do not participate in longitudinal cohorts, even if eligible. It remains difficult to truly understand if the current risk tools adequately reflect all of us, in particular those who are not adequately reflected in current prospective cohorts. Thus, a patient-provider discussion of the generalizability of the risk assessment and current recommendations is paramount to good clinical care.
Keywords: Cardiovascular Diseases, Myocardial Revascularization, Atherosclerosis, Lipids, Myocardial Infarction, Stroke, Risk Assessment, Risk Factors, Risk, Women's Health, Primary Prevention
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