Cross-Country Drug Availability and Comparability: Implications for International Price Comparisons

This paper explores cross-country drug availability and comparability, a key methodological issue in international drug price comparisons. Drug marketing and presentations, such as dosage form, strength, and formulation, vary considerably across countries. As a result, when conducting bilateral or multilateral comparisons, researchers face important trade-offs between the representativeness of their samples within countries and the precision of matching drug characteristics across countries. While previous studies have acknowledged these challenges, a more systematic treatment of comparability trade-offs can further improve ongoing research in this area. We describe these trade-offs in terms of selection bias and, using comprehensive international data from 2017, identify specific methods to characterize availability and comparability. Our analysis provides an in-depth understanding of how selection decisions influence the results, and therefore interpretation, of price comparisons. We conclude that treatment of drug availability and comparability is possible and can improve understanding of international drug price comparisons.