Angiography for Diagnosing Peripheral Arterial Occlusive Disease
examination. ‘Examination’ costs were assigned according to the experience gained in Study 1. These comprised costs for personnel and equipment on the basis of linear depreciation, including interest on a loan for the capital outlay, electricity costs (adjusted for the duration of use), costs for the examination and resting rooms (adjusted for the duration of use) and a fixed sum for administration. The overhead costs (‘other’) are for other personnel, furniture, cleaning, waiting room, insurance, maintenance of equipment, scientific literature, travel, seminars, telephone, literature for the waiting room and so forth; by their nature, these costs were independent of the imaging technique.
Personnel costs for the clinicians were calculated on the basis of a published analysis of salaries.23
For the technician (radiographer) the
tariff of the German civil service (Tarifvertrag für den öffentlichen Dienst [TVöD, Kommunen West]) was used, assuming (as in Study 1) an average of three years’ job experience (Entgeltgruppe 6, Stufe 3).24,25
The
personnel costs were based on the average working time that the various staff members (head/registrar, assistant physician, technician or radiographer) spent on the examination process.22
It
was assumed that the working time of the technicians increases in proportion to the usage time of the equipment; a high standard of qualification for the technician is needed. The working time of the clinicians for nce-MRA/FBI was assumed to be at least as long as for ce-MRA (anamnesis, etc., would be independent of the technique, while the greater time needed for diagnosis in nce-MRA/FBI would more than outweigh that required for placing the needle for contrast-medium injection in ce-MRA).
Occupation times of the MR suite are the sum of pre- and intra- diagnostic, acquisition and post-diagnostic times. Pre-diagnostic times include the preparation and placing of the patient in the scanner and documentation. For ce-MRA, extra time is required for preparing the contrast-medium injection. The intra-diagnostic times cover the start of the examination, the preparatory sequences (scout, TOF imaging for vessel localisation) and the imaging of four sequences that will later be subtracted from the contrast-enhanced sequences. For ce-MRA, extra time for the application of the contrast agent is added. Post- diagnostic times include the time between the end of the acquisition and patients leaving the MR room, cleaning the equipment, data handling, printing, archiving or other preparation of images, plus for ce-MRA the time needed to remove the injection needle. In Study 1, each of the four ce-MRA sequences was assumed to take one to 30 minutes, giving a total acquisition time of six minutes for ce sequences. Overall, the MR suite occupation time added up to 31–55 minutes.22
Published data on nce-MRA/FBI5–9 suggest that the
acquisition time needed to run the nce-MRA/FBI sequences requires the scanning of at least four body regions at three to eight minutes each, adding up to 12–32 minutes in all (average 22 minutes).
Purchase and maintenance costs for the equipment (MR machine and power injector) were considered to make up the equipment’s total costs. Standard operating hours were taken from the German Uniform Value Scale (Einheitlicher Bewertungsmaßstab [EBM]26
) as
seven x 12 hours = 84 hours per week. Occupation times for the equipment and MR suite were derived from scan and preparation times. On the basis of experience, an average MR suite was assumed to have an area of 15m2 with a rent of €7.20/m2.22 costs were taken to be €10 per investigation.22 were set at €40 per examination.22
Administrative The other overheads Costs of medication used by EUROPEAN CARDIOLOGY
of all patients were not included. In cases of technical failure, an MRA procedure would be followed by standard DSA, the cost of which was likewise taken into account. Costs for electricity were obtained from a reference hospital that meters electricity consumption at the MRA site, assuming energy costs of €0.20/kWh with operation and stand-by times of 84 hours per week each and 52 weeks per year.
For this analysis, variable costs for individual consumables such as contrast agents and syringes were not considered at first because of price differences across regions and different accounting policies across hospitals. In addition, Germany was chosen as the example to evaluate the total costs including consumables. The list prices were considered and comprised €55.99 for the most commonly used gadolinium-based MRI contrast agent (Magnevist®, Bayer Schering Pharma AG, list price at July 2009 for a single dose of 15ml) and €3.31 for other consumables, totalling €59.30 as maximum costs according to the German medication index (Ifap® Index).27
No discounts were
costs of the contrast agents are declared and reimbursed separately as add-ons to the reimbursement of the MRA. While this tariff is used for accounting within and between departments of hospitals in Germany, it is also used for calculating the procedure costs in reference hospitals in order to determine appropriate fixed costs. Tariff accounting is the preferred way to show any potential cost-related effects of alternative treatment pathways in the hospital setting.
considered. If, for example, accounting is based on the tariff of the German Hospital Society (Tarif der Deutschen Krankenhausgesellschaft, DKG-NT),28
A sensitivity analysis was performed in terms of the proportions of technical failures. The nce-MRA/FBI sequence is assumed to take on average 22 minutes in addition to the preparatory pulse sequences (scout, localiser, MRA sequences for vessel localisation, etc.). For the initial nce-MRA, the proportions of non-diagnostic images in clinical studies were reported to range from 6 to 34% of cases (average 20%).29–31 For the nce-MRA/FBI sequence, a similar proportion of non-diagnostic images is expected because of its technical disadvantages, such as the patient’s long stay in the machine and movement artefacts. These limitations can be considered as costs that must be incurred if a better image (higher resolution) is to be obtained. In cases of non-diagnostic images obtained by nce-MRA/FBI, it is assumed that a standard DSA for a final diagnosis will be performed in a different session. Therefore, calculations were performed using the average non-diagnostic proportion of 20%.29–34
Sensitivity analyses using 6 and 34% were
the average of 2% was used for the main calculation and the limits of 1 and 3% for sensitivity analyses. Costs of DSA for all calculations were obtained from Study 1,22
conducted to explore the effect of different proportions on the total costs of nce-MRA with nce-MRA/FBI. Similar calculations were performed for ce-MRA on the basis of reported values between 1 and 3%;29–31
and total investigation costs
were €176.63. As for ce-MRA, the costs of consumables for DSA (~€128 per examination according to list prices) were not taken into account.
In the analysis, the costs per minute were calculated as decimals with five digits for precision of results. All averages are expressed as arithmetic means. The data management and evaluation was performed with Microsoft® Office Excel 2003.
Results
Our cost analysis was strictly limited to the costs of routine investigations by two MRA techniques: ce-MRA and nce-MRA/FBI (as currently promoted by Toshiba) as an example for nce-MRA. The focus was on
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