Prescription-Event Monitoring
Introduction
For more than 30 years the importance of post-marketing surveillance to monitor the safety of medicines prescribed in ‘real life’ clinical practice has been recognised. Post-marketing surveillance (PMS) of new drugs is imperative to quantify common adverse drug reactions (ADRs) and to identify rare adverse reactions. Prescription-Event Monitoring (PEM), which was developed in the UK in the 1980s by Professor Bill Inman, provides proactive post-marketing surveillance on a national scale.
Overview of PEM
Using a simple questionnaire, known as a ‘Green Form’, general practitioners (GPs) who prescribe a new medicine are asked to report all events that have been recorded in the patients’ notes during a specific time-period since the patient started treatment with the medicine. By removing the need for the prescribing doctor to give an opinion about whether an event might have been caused by the medicine, PEM provides the opportunity to identify adverse events that may not have been suspected as being due to the drug under surveillance.
Prescription-Event Monitoring is both a hypothesis generating form of pharmacovigilance and a method which provides opportunities for quantitative analyses and comparative studies of drug safety signals. In addition, it has an excellent follow up procedure to obtain additional information about selected events of clinical importance. This enables clinical evaluation of the causal association of the event with the drug being monitored or the outcome of pregnancy to be ascertained. The methodology is flexible and has been adapted to address specific safety issues, for example for the PEM studies of the COX-2 inhibitors, information was collected on patients’ past medical history, also their past and current use of particular medications.
Prescription-Event Monitoring is the only method of post-marketing surveillance in Europe that can evaluate the safety of new medicines soon after launch, in cohorts that frequently comprise over 10 000 patients. Since the 1980s, 100 PEM studies have been completed and currently more than 20 studies are being conducted.
Modified PEM
For certain drugs, the information collected using standard prescription-event monitoring (PEM) is not sufficient to fulfil the aims of the study. In these situations, the DSRU uses modified PEM methodology (M-PEM). M-PEM methodology can be classified as an extension of the standard PEM methodology.