Objectives: Coronary artery disease (CAD) is still the most common cause of death globally. Chest pain that occurs regularly with activity, after eating, or at other predictable times is the most common sign of CAD. Nevertheless around 90% patients showing up in German GP offices with chest pain suffer from other diseases. The pathway for diagnosing CAD in the German ambulatory sector is partly driven by reimbursement structures. The statutory sick-funds do not cover for e.g. coronary-CT. Ultra-sensitive phonocardiography is a new technology to aid the early rule-out of CAD. This cost comparison modeled the consequences of applying this new test to German reimbursement reality.  

Methods: We developed a decision tree model based on the 2016 German CAD-diagnostic algorithm, but only accepted methods reimbursed by statutory sick-funds in the ambulatory setting. We implemented the results of a database of 1,664 symptomatic patients of the rule out device and modeled a population of typical patients showing up in a physicians` office with chest pain. Charges were derived from the 2018 German EBM-tariff. Probabilistic sensitivity analysis (PSA) was performed. Analytic tools were MS-Excel 2016 and TreeAge®.  

Results: The population had a mean age of 57.3 years, 51.5% female of which 10.4% suffered from obstructive CAD.  Use of phonocardiography (CADScore®, Acarix A/S) in addition to the recommended pretest probability calculator (Diamond-Forrester) caused a reduction in diagnostic costs of 21.5% (422 € vs. 331 €), excluding the additional cost of the CADScore® System. The main reason for the cost reduction is the sharp increase in the proportion of patients with either very low pretest probability (<15%) or CAD being ruled out by the phonocardiography system. The percentage of patients being ruled out from further diagnostics increased from 14.4% to 41%. The use of coronary angiography in the diagnostic process dropped from 22.0% to 16.9%.  Sensitivity analyses applied to the sensitivity and specificity of the phonocardiography system confirmed the cost advantage of the phonocardiography system over a wide range parameter range. However, an increase in the overall false negative rate of the diagnostic process has to be noted (26% without, 33% with phonocardiography), whereas the false positive rate dropped from 13.5% (without) to 9.7% (with phonocardiography).

Conclusion: Ultra-sensitive phonocardiography has proven to be a clinically relevant diagnostic measurement in several clinical trials. The economic effect was mainly driven by a reduction of coronary CTs. Given the German scheme with coronary-CT in the guidelines, but not reimbursed the ultra-sensitive phonocardiography proved also to reduce costs for the same diagnostic success. Saved radiation and overall cohort risk-reduction was not studied. The use of this new technology may save overall financial resources in CAD diagnostic in Germany.