The PROMISE trial is an NHLBI-funded randomized comparative effectiveness trial that compared anatomic testing (≥ 64 detector CT angiography) versus functional testing (exercise ECG, stress nuclear, or stress echocardiography) as the initial diagnostic test in patients with new onset symptoms suspicious for coronary artery disease in whom clinicians required diagnostic testing for further evaluation. An economic substudy was conducted to assess economic outcomes and cost effectiveness from a US societal perspective.
Material and methods
The PROMISE study randomized 10.003 patients in the US and Canada between 2010 and 2013. We prospectively collected detailed resource consumption data, including the initial testing strategy, along with any subsequent tests and therapies employed. Cost weights for resource consumption were derived from prospectively collected hospital billing data for US patients (with charge to cost conversion), while physician costs and outpatient testing costs were derived from Medicare fees. The primary aim of this part of PROMISE is to compare total medical costs for the two diagnostic testing arms by intention to treat. Costs have been adjusted for inflation and reported in 2014 dollars ($).
Mean age was 60.8 ± 8.3 years, and 53% were female. Cardiac risk factors include, hypertension in 65%, diabetes in 21%, dyslipidemia in 68%, obesity (BMI > 30) in 48%, peripheral or cerebrovascular disease in 6%, past or current tobacco use in 51%, and family history of premature coronary artery disease in 32%. The primary symptom was chest pain in 73% and exertional dyspnea in 15%. Among those receiving an initial functional test (4831 patients), 68% received nuclear testing, 22% stress echo and 10% exercise ECG; 29% were pharmacologic. A total of 4818 patients underwent CTA as an initial test. The cost of a CTA test was estimated to be $404. For the functional tests, the cost of echocardiography with an exercise stress test was $514, the cost of echocardiography with a pharmacologic stress test was $501, the cost of a nuclear test with exercise was $946 and a nuclear pharmacologic stress testing was estimated to be $1132. The cost of an ECG-only stress was $174. CTA increased the use of invasive catheterizations by 4% over functional testing, and those in the CTA arm were twice as likely to have revascularization (311 patients [6,2%] vs. 158 patients [3,2%]). Fifty one percent of the CTA patients referred for catheterization underwent revascularization compared with 39% of the functionally studied patients. After looking at the average cost of each test and subsequent follow-up testing, the net cost in the first 90 days was $279 higher on average with CTA than with functional testing. By year 2, however, the cost differential was only $29.
In stable patients with new chest pain, CTA strategy improved efficiency of use of invasive evaluation. But despite lower testing costs for CTA compared with functional tests, net effect was to drive a small (<$500), statistically non- significant increase in cost.