Differences in the methodology and data of economic evaluations of a health programme. The case of hepatitis B vaccination programmes in Spain

Economic evaluations of hepatitis B vaccination programmes in Spain or particular regions of Spain were identified and analysed, and their methodologies and data were compared. The results revealed important differences in methodology and the way in which different parameters, such as duration of immunity, costs and sources of cost data, were defined and measured. Some of these variations could be justified by the need to adapt studies to specific contexts, while others appeared arbitrary. Although it is understandable that there should be a substantial amount of heterogeneity between studies, greater efforts need to be made to reduce unnecessary variations in the way in which different parameters are measured. Increasing standardisation in methodology, which nevertheless takes into account inevitable variations due to changing circumstances and perspectives, will help to make economic evaluation a more attractive proposition for decision makers.