Calibration of the Pooled Cohort Equations for Atherosclerotic Cardiovascular Disease An Update

The latest guidelines from the American College of Cardiology and American Heart Association, released in fall 2013, provide a long-anticipated update to the recommendations of the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). The guidelines incorporate a new risk score for atherosclerotic cardiovascular disease that includes stroke as well as coronary heart disease. After publication, the new pooled cohort equations (PCEs) were evaluated in 15 studies from the United States and Europe, most of which used cohorts that were more contemporary than those used in developing the guidelines. In almost all of these external validation cohorts, the PCEs overestimated the observed risk. This narrative review provides an update of the published reports, an overview of the strengths and weaknesses of these validation efforts, and a discussion of possible reasons for the discrepancies. These issues may be useful in a recalibration process designed to better match predicted and observed risks relevant for current clinical practice.