Purpose: For the initial assessment of patients with stable chest pain syndrome, coronary CT angiography (CTA) has evolved as an alternative to functional testing (FT) for the detection of obstructive coronary artery disease (CAD). However, uncertainty remains about its overall diagnostic value including the identification of non-obstructive CAD given the current absence of treatment. Our objective was to evaluate clinical outcomes, costs, and cost-effectiveness of different anatomic and functional test modalities in the light of potential treatments for non-obstructive CAD.
Methods: Design: Cost-effectiveness analysis using a microsimulation model to simulate incidence and progression of CAD (non-obstructive and obstructive) as a function of patient age, gender and cardiac risk profile. Mortality risk depended on patient's demographics, CVD and treatment status. Potential treatment effect on non-obstructive CAD was based on decreasing the Framingham risk score (hypothetical life-style modifications) and secondary prevention studies. Target population: Patients with chronic chest pain syndrome. Time horizon: Diagnostic phase, lifetime. Discount rate: 3%. Perspective: Societal. Interventions: (1) preventive treatment (SOC) to (2) CTA (CTA), (3) stress-EKG/stress-echo/SPECT (in 20%, 50%, and 30%) (FT), (4) FT followed by CTA if FT positive or indeterminate (FT-CTA), (5) CT followed by FT if CTA positive or indeterminate (CTA-FT). Outcomes: Diagnostic results, discounted quality-adjusted life expectancy (QALE) and lifetime costs, incremental cost-effectiveness ratio (ICER).
Results: In our base case population (males, 50 years, low risk for CAD) the prevalence of CAD was estimated at 53% (13% obstructive). FT correctly identified 13% (10%) at $469/patient; CTA 44% (12%), CTA-FT 49% (9%), FT-CTA 17% (9%) at $599, $663, and $605 per patient, respectively. The model predicted an average remaining life expectancy of 22.01 quality-adjusted life years (QALY) for SOC and 22.27, 22.33, 22.20 and 22.21 QALYs for FT, CTA, CTA-FT, and FT-CTA, respectively. This resulted in an ICER of $13,800/QALY for FT compared to SOC, and of $20,000/QALY for CTA vs. FT; CTA-FT and FT-CTA were both dominated. When applying potential treatment benefit to patients with non-obstructive CAD, CTA dominated most other strategies across a broad range of CAD prevalences (figure).
Conclusion: Preliminary analyses indicate that CTA is cost-effective compared to functional testing as an initial evaluation method for patients with chronic chest pain. These results are independent of treatment effect on non-obstructive CAD.