National and transnational drug shortages: a quantitative descriptive study of public registers in Europe and the USA.

Public drug shortage registers are vital data sources for proactively maintaining and managing a reliable drug supply. However, our study demonstrates that much work remains to standardize the contents and quality of public register data. Shortages may not be solely a consequence of manufacturing disruptions but may reflect other contributing factors in the international drug distribution and supply mechanisms, including price differences and profit margins between national pharmaceutical markets. Data to perform practical and useful international comparisons to understand these shortages are required.