Outcomes After Coronary Artery Calcium and Other Cardiovascular Biomarker Testing Among Asymptomatic Medicare Beneficiaries

Abstract

Biomarkers improve cardiovascular disease (CVD) risk prediction, but their comparative effectiveness in clinical practice is not known. We sought to compare the use, spending, and clinical outcomes in asymptomatic Medicare beneficiaries evaluated for CVD with coronary artery calcium (CAC) or other cardiovascular risk markers. We used a 20% sample of 2005 to 2011 Medicare claims to identify fee-for-service beneficiaries aged ≥65.5 years with no CVD claims in the previous 6 months. We matched patients with CAC with patients who received high-sensitivity C-reactive protein (hs-CRP; n=8358) or lipid screening (n=6250) using propensity-score methods. CAC was associated with increased noninvasive cardiac testing within 180 days (hazard ratio, 2.22, 95% confidence interval, 1.68-2.93, P<0.001, versus hs-CRP; hazard ratio, 4.30, 95% confidence interval, 3.04-6.06, P<0.001, versus lipid screening) and increased coronary angiography and revascularization. During 3-year follow-up, CAC was associated with higher CVD-related spending ($6525 versus $4432 for hs-CRP, P<0.001; and $6500 versus $3073 for lipid screening, P<0.001) and fewer CVD-related events when compared with hs-CRP (hazard ratio, 0.74, 95% confidence interval, 0.58-0.94, P=0.017) but not compared with lipid screening (hazard ratio, 0.84, 95% confidence interval, 0.64-1.11, P=0.23). CAC testing among asymptomatic Medicare beneficiaries was associated with increased use of cardiac tests and procedures, higher spending, and slightly improved clinical outcomes when compared with hs-CRP testing.