Comparison of cardiovascular risk assessment algorithms to determine eligibility for statin therapy: implications for practice in Canada

Abstract

Background: New lipid management guidelines in the United States have created controversy regarding risk assessment using the new Pooled Cohort Equations (PCE) which might overestimate cardiovascular risk and identify an excessive number of patients as new candidates for statin therapy.

Methods: We compared the Framingham Risk Score (FRS) used in Canada with PCE, the FRS version used in Adult Treatment Panel III (ATP III), Reynolds Risk Score (RRS), and Systematic Coronary Risk Evaluation (SCORE) using patient profile simulation of 10 cohorts of 100,000 each (total n = 1,000,000 for each comparison). Patients with diabetes, established cardiovascular disease, or family history of premature cardiovascular disease were not considered, mimicking uncomplicated primary prevention. Analyses were performed separately for men and women and for black individuals when feasible.

Results: SCORE (high-risk version) was most concordant with FRS in men, whereas PCE was most concordant in black women. Compared with FRS, all other algorithms except SCORE (high-risk version) identified more simulations as low risk. Reclassification from low FRS to a higher risk was not seen using RRS or ATP III and seen in < 5% of simulations using PCE, affecting predominantly black subject simulations.

Conclusions: Choice of risk calculator leads to systematic differences in risk categorization that can influence eligibility for lipid-lowering therapy. Compared with FRS, an isolated switch to PCE, RRS, or ATP III is unlikely to lead to substantial reclassification from low to higher risk categories in Canada.