Postmarketing Surveillance: The Viewpoint of a Newcomer to Pharmacoepidemiology

Abstract

Prescription-event monitoring (PEM) is a system of postmarketing surveillance for new chemical entities that has been developed by Inman. Its principal aim is to generate hypotheses about adverse drug reactions (ADRs) that have not been identified during clinical trials. The operation covers the whole of England (total population approximately 50 million). Cohorts of 10,000–20,000 patients are identified from photocopies of prescriptions that are provided by the Prescription Pricing Authority. Event data are obtained from a standard questionnaire (green form) that is sent to the prescribing doctor at an interval after the date on the original prescription. Serious events are followed up further via the general practitioner (GP), and deaths are routinely investigated using GP medical records and copies of death certificates. Since 1984, 32 drugs have been included in PEM. The data base is used to provide examples of the methods of data analysis and further follow-up of signals. The future of PEM will be discussed in the context of the general development of pharmacoepidemiology in the United Kingdom. It is concluded that this should acquire a broader perspective, and needs to address issues of recruitment, training and dissemination of information, and that a sound academic base is required.