Economics of myocardial perfusion imaging in Europe - The empire study

Physicians use myocardial perfusion imaging (MPI) to a variable extent in patients presenting with possible coronary artery disease (CAD). There are few clinical data on the most cost-effective strategy although computer models predict that routine use of MPI is cost-effective. We have studied 400 patients presenting to 8 hospitals for the diagnosis of CAD. The hospitals were regular users or non-users of MPI with one of each in 4 countries (F, D, I, UK). Information was gathered retrospectively on presentation, investigations, complications, and clinical management, and patients were followed up 2 years in order to assess outcome. Costs and prices were estimated in each hospital. Pre- and post test probabilities of CAD were computed for diagnostic tests and each test was also assigned as diagnostic or part of management. Diagnostic strategies defined were 1: Ex-ECG/angio, 2: Ex-ECG/MPI/angio, 3: MPI/angio, 4 angio. Primary outcome measures were the cost and accuracy of diagnosis, the cost of subsequent management, and clinical outcome. Secondary measures included prognostic power, normal angiography rate, and rate of angiography not followed by revascularisation. Mean diagnostic costs per patient were: Strategy 1: £333, 2: £339, 3: £288, 4: £975 (P<0.001). Mean diagnostic cost in the MPI user centres was £373 and in the non-users £519 (P<0.001). Mean probability of the presence of CAD when the final clinical diagnosis was CAD present were, strategy 1: 0.89, 2: 0.91, 3: 0.95, 4: 0.97, and when CAD was absent, 1: 0.22, 2: 0.11, 3: 0.12, 4: 0.05 (P<0.01). Thus quality of diagnosis for the scintigraphic strategies (2 and 3) was higher than strategy I and almost equal to the angiographic strategy (4). Prognostic power at diagnosis was higher (P=0.001) and normal coronary angiography rate was lower (P=0.01) in the scintigraphic centres and strategies. We conclude that diagnostic strategies routinely using MPI are cheaper and equally effective compared with strategies that do not use MPI.