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Coronary artery calcium (CAC) scans are increasingly used in asymptomatic populations for detecting subclinical coronary disease. CAC scans lead to reclassification of risk for some subgroups of patients but the impact of CAC scans on subsequent imaging, therapeutic interventions and adverse ischemic events is not well understood. The objectives of the study were to compare post-index imaging, therapeutic interventions, and adverse ischemic event rates between patients with CAC scan and those denied CAC scan.
Case group (N=2,679) consisted of patients not requiring pre-authorization who underwent CAC scan identified through insurance claims between 01/01/2006 and 04/30/2011. Control group (N= 1,135) consisted of patients for whom CAC was requested in a pre-authorization model between 01/01/2005 and 08/31/2011 but was not a covered service, due to benefit design. Population was divided into two groups, high versus low/intermediate risk, based upon pre-existing comorbidities found in claims. Testing and interventions 6 months after CAC scan or CAC request were analyzed. Differences were compared through chi-square or fisher exact tests. Survival analysis was used for adverse events.
High risk patients constituted 20.2% and 23.5% of case and control group, respectively (p<0.05). Among those at low or intermediate risk, a similar proportion of both case and control patients received an imaging test within 6 months (23.2% vs.23.8%, p=0.5); proportions were comparable between groups regardless of imaging test studied. The rates of therapeutic interventions (both surgical and pharmaceutical) were similar between the groups. Age-sex adjusted incidence rate ratio for adverse events was 1.1 among cases relative to controls [95% CI 0.36-3.38].
CAC scans were not associated with fewer ischemic events or reduced use of additional imaging tests among low or intermediate risk patients. One in five patients who received CAC may be considered as inappropriate use according to current guideline, which state that CAC is not useful in high risk patients.
Poster Sessions, Expo North
Saturday, March 09, 2013, 10:00 a.m.-10:45 a.m.
Session Title: Coronary Risk Factors and Management
Abstract Category: 28. Quality of Care and Outcomes Assessment
Presentation Number: 1115-106
- 2013 American College of Cardiology Foundation