Comparing costing results in across country economic evaluations: the use of technology specific purchasing power parities

The number of economic evaluations conducted on a multinational basis is increasing. Therefore, techniques are required to compare the results of such studies in a meaningful manner. This paper explores different approaches to comparing across country cost data applied to a European study of dialysis therapy for end-stage renal disease. A price and volume index is created at the level of the individual health care technology and compared to an exchange rate conversion and published purchasing power parities (PPPs). Both exchange rate and PPP conversions when published rates are used fail to accurately reflect the true resource use of the applied health care example. These differences can be related to specific issues of input mix and price variation. Alternatively, the use of technology specific PPPs provided a more robust approach for international comparisons and also have the potential for use in multi-centre economic evaluations within the same country.