Opportunities and pitfalls of registry data for clinical research.

The use of disease registries for clinical epidemiological studies has become increasingly common and has led to advancements in the understanding of many disease processes. The availability of demographic and disease characteristic data on large patient populations, coupled with the minimal cost and relative speed of conducting retrospective investigations, provide an attractive alternative to original data collection. However, limitations inherent to the data collection process can result in the loss of generalizability and introduce bias, leading to erroneous or invalid results. Recognition and identification of these limitations will be unique to each investigation and to the registry being used. The purpose of this article is to highlight the opportunities that registries provide for researchers while presenting potential pitfalls in their use. We conclude with a discussion of a practical approach when considering registry data for clinical research.