Cost-effectiveness of a Novel Indication of Computed Tomography of the Coronary Arteries

OBJECTIVE: A common strategy for excluding coronary artery disease among patients presenting with low-risk chest pain is observation unit (OU) admission with serial cardiac biomarkers and stress testing for cardiac risk stratification. Patients with positive- or indeterminate-stress tests are often admitted for cardiac catheterization despite a low likelihood of disease. The aim of this study is to estimate the cost-effectiveness of computed tomography of the coronary arteries (CTCA) in the OU for the evaluation of low-risk chest pain patients with indeterminate- or positive-stress test results. METHODS: We conducted a decision analytic study to compare health outcomes and costs between 3 cardiac risk-stratification strategies in a population of patients at low cardiac risk admitted to the OU, who later had indeterminate- or abnormal-stress tests. Our population and test characteristics were based on data obtained both from the published literature and from a retrospective cohort review previously performed at our institution. The 3 strategies compared were (1) A CTCA strategy in which patients with positive- or indeterminate-stress tests subsequently underwent CTCA, and only received catheterization if results were positive, (2) A standard-of-care arm in which all patients with positive- or indeterminate-stress tests were admitted for catheterization, and (3) A do-nothing strategy in which all patients were discharged home after stress testing regardless of outcome. Outcomes measured were cost of care and life expectancy. Sensitivity analysis was performed with a multivariate Monte Carlo methodology. RESULTS: Both the CTCA and standard-of-care strategies dominated the do-nothing strategy in the base case. When comparing the standard-of-care with the CTCA strategy, the incremental cost-effectiveness ratio was $3,423,309 per additional year of life gained. Sensitivity analysis showed that below a willingness to pay of $600,000 per additional year of life, CTCA was the most likely strategy to be cost-effective. CONCLUSIONS: In this computer-modeled analysis, the addition of CTCA following positive- or indeterminate-stress tests to an OU cardiac risk-stratification pathway for low-risk chest pain patients achieved significant cost savings with a small decrease in life expectancy per patient. Adding CTCA after indeterminate- or positive-stress test results is a cost-effective intervention for further risk-stratifying low-risk chest pain patients in the OU setting before proceeding to traditional coronary angiography.