, Volume 25, Issue 11, pp 1145-1151,
Open Access This content is freely available online to anyone, anywhere at any time.

Coronary Risk Assessment by Point-Based vs. Equation-Based Framingham Models: Significant Implications for Clinical Care

Abstract

BACKGROUND

US cholesterol guidelines use original and simplified versions of the Framingham model to estimate future coronary risk and thereby classify patients into risk groups with different treatment strategies. We sought to compare risk estimates and risk group classification generated by the original, complex Framingham model and the simplified, point-based version.

METHODS

We assessed 2,543 subjects age 20–79 from the 2001–2006 National Health and Nutrition Examination Surveys (NHANES) for whom Adult Treatment Panel III (ATP-III) guidelines recommend formal risk stratification. For each subject, we calculated the 10-year risk of major coronary events using the original and point-based Framingham models, and then compared differences in these risk estimates and whether these differences would place subjects into different ATP-III risk groups (<10% risk, 10–20% risk, or >20% risk). Using standard procedures, all analyses were adjusted for survey weights, clustering, and stratification to make our results nationally representative.

RESULTS

Among 39 million eligible adults, the original Framingham model categorized 71% of subjects as having “moderate” risk (<10% risk of a major coronary event in the next 10 years), 22% as having “moderately high” (10–20%) risk, and 7% as having “high” (>20%) risk. Estimates of coronary risk by the original and point-based models often differed substantially. The point-based system classified 15% of adults (5.7 million) into different risk groups than the original model, with 10% (3.9 million) misclassified into higher risk groups and 5% (1.8 million) into lower risk groups, for a net impact of classifying 2.1 million adults into higher risk groups. These risk group misclassifications would impact guideline-recommended drug treatment strategies for 25–46% of affected subjects. Patterns of misclassifications varied significantly by gender, age, and underlying CHD risk.

CONCLUSIONS

Compared to the original Framingham model, the point-based version misclassifies millions of Americans into risk groups for which guidelines recommend different treatment strategies.

This research was presented at the annual meetings of the American Geriatrics Society (Chicago, April 30, 2009) and the Society of General Internal Medicine (Miami, May 14, 2009) and at the Bay Area Clinical Research Symposium (San Francisco, October 3, 2008)
Dr. Polansky's contribution to this article is made in his personal capacity, not as a Centers for Medicare & Medicaid Services employee. The opinions (or conclusions) expressed are those of Dr. Polansky and not necessarily of CMS or the US Department of Health and Human Services.