The Pooled Cohort Equations 3 Years On

Abstract

In November 2013, a 10-year risk prediction tool known as the Pooled Cohort Equations (PCE) was released as the foundational basis for cardiovascular prevention guidelines in the United States.1 However, the PCE calculator was soon found to overestimate cardiovascular risk in 3 major contemporary US cohorts: the Physicians’ Health Study, the Women’s Health Study, and the Women’s Health Initiative-Observational Cohort.2 Similar overestimation of risk had already been observed in the MESA (Multi-Ethnic Study of Atherosclerosis) and the REGARDS study (Reasons for Geographic and Racial Differences in Stroke), 2 contemporary US cohorts used for external validation by the guideline creators. The poor calibration observed in these 5 contemporary external cohorts suggested that overreliance on older data occurred during the guideline modeling process (Figure). Indeed, the PCE were derived from studies that enrolled between 1968 and 1990. These older data do not reflect the lower current rates of cardiovascular disease that largely result from secular shifts in smoking, diet, exercise, and blood pressure control, issues of which the prevention community and professional societies should rightly be proud. Figure. US death rates per 100 000 from cardiovascular disease (CVD) and coronary heart disease (CHD). The Pooled Cohort Equations were developed with data from studies that enrolled between 1968 and 1990. However, cardiovascular event rates have significantly declined over the past 40 years, which may explain why overestimation of risk has been seen when these equations are evaluated in contemporary external validation cohorts. The issue of overestimation with the PCE risk calculator …