Trans-atlantic data harmonization in the classification of medicines and dietary supplements: a challenge for epidemiologic study and clinical research.

OBJECTIVES: As international scientific collaboration increases, there is a growing requirement for research data to be comparable among countries. Despite the importance of medication and dietary supplement data in research, there are no international standards for the collection and storage of these data. In the absence of such standards, we needed to adopt a strategy for classification and coding of medications and dietary supplements to meet demands of our multi-national study.
METHODS: Given the inter-country variations in nomenclature that characterize prescription, over-the-counter (OTC) medications, traditional herbal medicines, and dietary supplements, we adopted RxNorm as a data standard for medication data, and developed an independent system that extends this standard and allows for flexible and scalable data collection for dietary supplements.
RESULTS: RxNorm was implemented in May 2005 and as of July 2006, coverage has been 99%, at the level of active ingredients, of all the medications reported in our study. Development of a dietary supplement database began in August 2005, and has thus far coded some 1200 dietary supplements and 650 infant formula products and forms from the four countries in our study.
CONCLUSION: The methods we have used to collect, store, and manage medication and dietary supplement data serve as interim solutions until international standards are developed. It is hoped that such standards will ultimately emerge, and that our strategy and data model will be of value in other research environments in the immediate future.