Does CAC testing alter downstream treatment patterns for cardiovascular disease?

To assess if coronary artery calcium (CAC) scans influence treatment patterns as reflected by subsequent rates of cardiac imaging and therapeutic interventions, and their effect on ischemic events downstream.

Longitudinal observational study from January 1, 2005, through August 31, 2011, using a large managed-care medical and pharmacy claims database.

Two cohorts were evaluated: CAC patients who received CAC testing, and Reference patients, subject to preauthorization, who were denied CAC scans. Patients were adults less than 65 years old. Index date was CAC scan date for CAC and pre-authorization request date for Reference. Patients were stratified into high-risk and non-high-risk categories; outcomes were analyzed only for non-high-risk where CAC scores could potentially modify risk classification. Cardiac imaging, coronary revascularizations, and pharmaceutical interventions were evaluated for 6 months post index and adverse ischemic events were assessed using all available follow-up time.

The study included 2679 CAC and 1135 Reference patients. Among non-high-risk patients, similar proportions of both groups received an imaging test within 6 months (23.2% vs 23.8%, respectively; P = .5); revascularization rates and pharmaceutical utilization were similar. Adverse events were rare. Age-sex adjusted incidence rate ratio for adverse events was 1.1 (95% CI, 0.36-3.38) among CAC relative to Reference. High-risk patients, considered inappropriate for CAC testing, represented 20.2% and 23.5% of CAC and Reference, respectively (P <.05).

Patients having CAC scans were not associated with fewer downstream ischemic events nor with reduced subsequent imaging and therapeutic interventions among non-high-risk patients. Results also indicated inappropriate testing of high-risk patients.