Updating the 2013 pooled cohort equations (PCEs) with more recent patient populations and new statistical methods results in approximately 11.8 million U.S. adults migrating to a lower-risk category, potentially affecting which therapies they would be indicated for to combat atherosclerosis.
Major guidelines recommend using the 10-year cardiovascular disease (CVD) risk estimates derived from the 2013 PCEs to inform treatment decisions for aspirin, statins and blood pressure medication. But the PCEs have been reported to misestimate risk and some researchers are concerned they were developed using patient cohorts that don’t reflect the current era of medical practice—such as the original Framingham Heart Study group, which was 30 to 62 years old in 1948.
Steve Yadlowsky, MS, and colleagues eliminated that group from the equation and added two more recent cohorts—the Jackson Heart Study and the Multi-Ethnic Study of Atheroscleroris, both of which had data from 2000 to 2012. In addition, they tweaked the statistical methods of the 2013 model, which was found to have significant overfitting and wide variation in the risk estimates of black patients.
“Because of the central role of PCEs in CVD prevention, improving accuracy could save lives by better targeting treatment to those who need it most and avoiding treatment-related adverse events among those who do not need therapy,” Yadlowsky and colleagues wrote in the Annals of Internal Medicine.
About 11.8 million U.S. patients deemed at high risk of CVD (10-year risk greater than 7.5 percent) under the old system would be reclassified to a lower-risk category with the new calculations, the researchers found.
Also, the new model improved the issue of “highly implausible” variation among black patients, who previously had risk estimates ranging from 80 percent lower to more than 500 percent higher than white counterparts with otherwise identical risk factor values.
Using the 7.5 percent threshold for “high risk” of CVD over a 10-year period, the revised PCEs correctly bumped 13 people who did not have a CVD event to a lower-risk category for each person who was incorrectly reclassified to low risk. The measured outcomes included nonfatal myocardial infarction, death from coronary heart disease and fatal or nonfatal stroke.
“Our results suggest that the revised PCEs will reduce overestimation of risk in general and may prevent adverse events, health care costs, and inflated expectations of absolute risk and corresponding absolute therapeutic benefit,” the researchers wrote. “Clinicians and patients should consider the potential benefits and harms of reducing the number of persons recommended aspirin, blood pressure, or statin therapy.”
Yadlowsky et al. said their findings highlight the importance of updating risk prediction tools over time. They suggested other researchers use different patient cohorts to validate their new model—a recommendation echoed by the authors of an accompanying editorial.
“The most notable limitation of Yadlowsky and colleagues' study is that results are from internal cross-validation and prospective hold-out validation,” wrote Andrew Paul De Filippis, MD, MSc, and Patrick Trainor, MS, MA, both with the University of Louisville in Kentucky.
“Although such validation is useful, results may differ when risk scores are applied to separate cohorts by independent investigators, as seen with the 2013 PCEs. Therefore, independent tests of these revised PCEs in independent cohorts are needed to determine appropriateness for clinical practice.”
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.