NEW YORK — A new study has found that coronary artery calcium scores are better than polygenic risk scores at predicting coronary heart disease (CHD) risk when added to traditional risk factors.
According to the authors of the work, published in JAMA on Tuesday, no prior investigation had made this comparison. "This study directly addresses a key knowledge gap identified by the recent [American Heart Association] Scientific Statement, among others, expressing a need to directly compare polygenic risk scores with coronary artery calcium scores for predicting risk of CHD," corresponding author Sadiya Khan, a professor in the department of medicine at Northwestern University Feinberg School of Medicine, wrote along with her colleagues.
One of the reasons the researchers wanted to make the comparison was because previous studies had suggested that polygenic risk scores were a good risk predictor of CHD. Moreover, there was a lingering question whether polygenic risk scores and coronary artery calcium scores would have additive power in predicting CHD risk.
While a polygenic risk score estimates inherited disease risk based on common genetic variants, a coronary artery calcium score represents subclinical disease burden.
For their study, the researchers used data from two large community-based cohorts: the Multi-Ethnic Study of Atherosclerosis, which involved 1,991 participants at six US centers, and the Rotterdam Study, which comprised 1,217 people in Rotterdam, Netherlands.
All participants were between 45 and 79 years old, of European ancestry, and free of clinical CHD.
By analyzing up to 17 years of follow-up data, the researchers compared whether risk prediction was more precise when a coronary artery calcium score or a polygenic risk score was added to current prediction models.
"When the coronary artery calcium score was added to a traditional risk factor-based model, there was a statistically significant and clinically meaningful improvement in risk discrimination," the authors noted. However, they did not notice such a boost when they added a polygenic risk score to a traditional risk factor model.
Moreover, the combination of the two scores had no additive predictive power compared with the coronary artery calcium score alone, they found.
The findings are in sync with guidelines by several professional societies, which prioritize the inclusion of a coronary artery calcium score over a polygenic risk score for predicting risk of CHD, the authors said.
Meanwhile, the researchers believe that polygenic risk scores may be useful for younger adults who have yet to develop coronary artery calcium. However, the study did not evaluate risk prediction for this group.
According to the authors, further studies are needed to understand whether communication of risk as quantified by coronary artery calcium scores and polygenic scores could translate to better clinical outcomes.
Highlighting one of the limitations of the study, the authors noted that all samples in the study were from individuals of European ancestry because most polygenic risk scores were derived from this population.
"Therefore, addressing the study question for a diverse sample of adults was not possible, thereby prohibiting assessing generalizability of the present findings and enhancing equity in genomics research," they wrote, adding that "ongoing efforts to expand risk prediction studies that examine multi-ancestry CHD polygenic risk scores in diverse populations are needed."