Transferability of health technology assessments and economic evaluations: a systematic review of approaches for assessment and application

BACKGROUND Health technology assessments (HTA) generally, and economic evaluations (EE) more specifically, have become an integral part of health care decision making around the world. However, these assessments are time consuming and expensive to conduct. Evaluation resources are scarce and therefore priorities need to be set for these assessments and the ability to use information from one country or region in another (geographic transferability) is an increasingly important consideration. OBJECTIVES To review the existing approaches, systems, and tools for assessing the geographic transferability potential or guiding the conduct of transferring HTAs and EEs. METHODS A systematic literature review was conducted of several databases, supplemented with web searching, hand searching of journals, and bibliographic searching of identified articles. Systems, tools, checklists, and flow charts to assess, evaluate, or guide the conduct of transferability of HTAs and EEs were identified. RESULTS Of 282 references identified, 27 articles were reviewed in full text and of these, seven proposed unique systems, tools, checklists, or flow charts specifically for geographic transferability. All of the seven articles identified a checklist of transferability factors to consider, and most articles identified a subset of 'critical' factors for assessing transferability potential. Most of these critical factors related to study quality, transparency of methods, the level of reporting of methods and results, and the applicability of the treatment comparators to the target country. Some authors proposed a sequenced flow chart type approach, while others proposed an assessment of critical criteria first, followed by an assessment of other noncritical factors. Finally some authors proposed a quantitative score or index to measure transferability potential. CONCLUSION Despite a number of publications on the topic, the proposed approaches and the factors used for assessing geographic transferability potential have varied substantially across the papers reviewed. Most promising is the identification of an extensive checklist of critical and noncritical factors in determining transferability potential, which may form the basis for consensus of a future tool. Due to the complexities of identifying appropriate weights for each of the noncritical factors, it is still uncertain whether the assessment and calculation of an overall transferability score or index will be practical or useful for transferability considerations in the future.