Cardiovascular risk calculators may overestimate, study finds

Cardiovascular risk calculators may regularly overestimate risk, according to a recent study.

Researchers performed a prospective, epidemiologic study of atherosclerotic cardiovascular disease (ASCVD) to compare the performance of the American Heart Association (AHA) and American College of Cardiology (ACC) ASCVD risk score versus other risk scores and to examine the use of preventive therapy based on these scores. The primary measurements were observed and expected events for the AHA-ACC-ASCVD score compared with 4 other common risk scores and their end points after 10.2 years of follow-up.

The other 4 risk scores were the Framingham Risk Study-Coronary Heart Disease (FRS-CHD) risk score, the Framingham Risk Study-Cardiovascular Disease (FRS-CVD) risk score, the Adult Treatment Panel III Framingham Risk Study-Coronary Heart Disease (ATPIII-FRS-CHD) risk score, and the Reynolds Risk Score (RRS). The study results appeared in the Feb. 17 Annals of Internal Medicine.

A total of 4,227 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) who were 50 to 74 years of age and had no diabetes at baseline were included in the study. Participants were 53.5% women and had a mean age of 61.5 years. Overall, 41.9% were white, 11.7% were Chinese, 26.3% were African American, and 20.2% were Hispanic. Baseline data from 2000 to 2002 were used to calculate risk.

The researchers found that the AHA-ACC-ASCVD risk score, the FRS-CHD risk score, the FRS-CVD risk score, and the ATPIII-FRS-CHD risk score overestimated cardiovascular events by 37% to 154% in men and 8% to 67% in women. The RRS, meanwhile, overestimated risk by 9% in men and underestimated it by 21% in women. Risk overestimation could not be explained by aspirin, lipid-lowering or hypertensive therapy, or interim revascularization.

The authors noted that results from MESA might not apply to the general primary prevention population and that some events may have been missed. However, they concluded that 4 of the 5 risk scores examined in this study significantly overestimated cardiovascular risk.

“If validated, overestimation of ASCVD risk may have substantial implications for individual patients and the health care system,” they wrote. They recommended that physicians treating patients similar to those in MESA consider using caution when interpreting the absolute risk generated by the AHA-ACC-ASCVD risk score.

The authors of an accompanying editorial pointed out that the importance of cardiovascular risk overestimation has been a subject of debate and noted that the team who developed the AHA/ACC guidelines stressed that their threshold of 7.5% risk was intended as a guidepost rather than a concrete indicator of the need for pharmacologic therapy. The editorialists said physicians could respond to the evidence of risk overestimation by recalibrating the AHA/ACC algorithm to track more closely with contemporary evidence, calculate several risk algorithms simultaneously, or do nothing and accept that more patients will receive statin therapy as a result.

“Physicians might also consider including revascularization procedures as an end point because they are relevant to our patients, are expensive, and are part of the trial end points used for efficacy evaluation,” the editorialists wrote.