Pharmacoepidemiological perspectives.

Parallel with increasing concerns about drug safety, the importance of drug surveillance and the application of epidemiologic techniques have grown rapidly during the past decades. The increasing use of computerized health care data facilitates the establishment of populations large enough (millions) to allow epidemiological studies. Such extensive studies are now being done routinely in North America. By the use of computerized pharmacy or billing records, drug exposure is linked to files which include diagnoses. These record-linkage systems provide "objective" drug histories for pharmacoepidemiological cohort and case-control studies and these large databases offer powerful tools for drug evaluation. A number of new drug-disease associations, many of potential importance for European populations, will be discovered through the increased use of large databases in North America. The European community needs to develop a strategy to respond to these overseas findings to protect society from either overreaction or underreaction to drug safety issues.