Introduction: Economic evaluations frequently make use of cost-effectiveness league tables to provide a comparative context for their results. But such league tables may have been criticised as potentially biased or misleading because of their small size, lack of detail, selection criteria, and mixing of results from studies with differing methodologies.

Objective: The objective of this study was to look for evidence of bias in previously published cost-effectiveness tables, and to explore the sensitivity of these tables to methodological differences in the studies they contain and in their construction.

Methods: The method adopted was to construct and analyze a large and detailed league table containing characteristics of and results from over 280 cost-effectiveness and cost-utility studies, published in different countries and years. The search strategy was to include all relevant studies included in two recently published databases of economic evaluations.

Discussion: The results indicate that systematic differences exist between countries and over time in the results of cost-effectiveness studies, but that most methodological differences make minor differences to the results.