Improving the transferability of costing results in economic evaluation : an application to dialysis therapy for end-stage renal disease
This thesis examines the challenges involved in transferring economic evaluation costing results between different health care settings. The first chapter suggests that improving the transferability of costing results is important for two main reasons. Firstly, if cost data are transferable this could allow policy makers in one location to use the cost results of a study from a different location and apply these to their own setting. Secondly, to maximise the ability to synthesise costing results within a multi-centre study, the data need to be transferable across the participating study centres/countries. In terms of factors which influence the transferability of costs results, a major consideration is the underlying economic heterogeneity of alternative health care settings. In addition the chapter identifies three main factors with scope for improvement, namely the reporting, standardisation and transparency of cost data, which are addressed throughout the thesis. Chapter 2 highlights that in terms of economic evaluation methodology, greater attention has been devoted to the benefit component compared to costing methodology. The chapter goes onto reveal that although costing issues such as discounting are increasingly being taken into account by health economists, there are other areas with clear scope for methodological development. In particular, the calculation of unit costs, the level of detail in collecting cost data, patient cost measurement and the conversion of cost results into a common currency are described. A description of the clinical area for this thesis, end-stage renal disease (ESRD), is provided in Chapter 3. The aim of Chapter 4 is to examine the choice of approach taken to calculate unit costs in multi-centres studies. The empirical work presented in Chapter 5 explores whether detailed unit costing approaches (bottom-up) might be necessary and favourable to more readily available costs (top-down), even if this implies a greater use of data collection resources. The focus of the thesis moves from health service costing to patient costing and the notion of a societal perspective in Chapter 6. Chapter 7 addresses the issue of reporting costing results by converting cost results into a common currency base. The main approaches to converting costs, namely exchange rates and published purchasing power parities (PPPs) are described, along with their respective limitations.