Methodological reviews of economic evaluations in health care: what do they target?

INTRODUCTION AND
OBJECTIVES: An increasing number of published studies of economic evaluations of health technologies have been reviewed and summarized with different purposes, among them to facilitate decision-making processes. These reviews have covered different aspects of economic evaluations, using a variety of methodological approaches. The aim of this study is to analyze the methodological characteristics of the reviews of economic evaluations in health care, published during the period 1990-2010, to identify their main features and the potential missing elements. This may help to develop a common procedure for elaborating these kinds of reviews.
METHODS: We performed systematic searches in electronic databases (Scopus, Medline and PubMed) of methodological reviews published in English, period 1990-2010. We selected the articles whose main purpose was to review and assess the methodology applied in the economic evaluation studies. We classified the data according to the study objectives, period of the review, number of reviewed studies, methodological and non-methodological items assessed, medical specialty, type of disease and technology, databases used for the review and their main conclusions. We performed a descriptive statistical analysis and checked how generalizability issues were considered in the reviews.
RESULTS: We identified 76 methodological reviews, 42 published in the period 1990-2001 and 34 during 2002-2010. The items assessed most frequently (by 70% of the reviews) were perspective, type of economic study, uncertainty and discounting. The reviews also described the type of intervention and disease, funding sources, country in which the evaluation took place, type of journal and author's characteristics. Regarding the intertemporal comparison, higher frequencies were found in the second period for two key methodological items: the source of effectiveness data and the models used in the studies. However, the generalizability issues that apparently are creating a growing interest in the economic evaluation literature did not receive as much attention in the reviews of the second period. The remaining items showed similar frequencies in both periods.
CONCLUSIONS: Increasingly more reviews of economic evaluation studies aim to analyze the application of methodological principles, and offer summaries of papers classified by either diseases or health technologies. These reviews are useful for finding literature trends, aims of studies and possible deficiencies in the implementation of methods of specific health interventions. As no significant methodological improvement was clearly detected in the two periods analyzed, it would be convenient to pay more attention to the methodological aspects of the reviews.