Modified Prescription-Event Monitoring

Since the 1980s, the DSRU has become well-known for conducting pharmacoepidemiological studies based in primary care using the standard technique of Prescription-Event Monitoring (PEM) (see PEM publications). The DSRU no longer conducts standard PEM studies. In parallel with scientific developments in pharmacoepidemiology and regulatory requirements in pharmacovigilance, the technique has evolved to become a more targeted safety study known as Modified PEM (M-PEM). These studies use enhanced customized data collection questionnaires to examine specific recognised or suspected safety risks of a medicine. Questions include those related potential risks, identified risks and missing information in Risk Management Plans (RMPs). M-PEM studies combine the advantages of standard PEM studies with a more targeted approach that addresses specific research questions to better understand recognised or suspected risks of a medicine. M-PEM is well-suited to risk management studies investigating the safety or utilisation of drugs in primary care.

Modified Prescription-Event Monitoring is explained in this short video:

Key facts about Modified Prescription-Event Monitoring

  • Suited to risk management studies for products intended for use in primary care, spanning many disease and therapeutic areas
  • Covers prescribing by NHS GPs at a national scale in England
  • Study design elements include exploration of relevant multiple outcomes (utilisation and/ or safety), sample size calculations, cohort accrual procedures, and the timing and method of data collection.
  • Custom questionnaires can include those related potential risks, identified risks and missing information in RMPs or can be designed to address specific regulatory issues
  • Single or multiple data capture phases enable abstraction of clinical information from medical chart review by prescribers responsible for treatment initiation in primary care, over a time frame relevant to study needs analysis plans can be tailored to address novel analytical issues and also convey thoughtful, appropriate, and comprehensive analysis of the data.
  • Study reports are prepared with scientific rigour to provide succinct presentation of results relevant to the product’s safety and efficacy.

The M-PEM study process:

M-PEM flow chart

Note that an ‘event’, as used in this study, is defined as “any new diagnosis, any reason for referral to a consultant or admission to hospital, any unexpected deterioration (or improvement) in a concurrent illness, any alteration of clinical importance in laboratory values, or any other complaint that was considered of sufficient importance to enter into the patient’s notes”.


All PEM GP practices
Map (above) showing all GP practices which have participated in PEM or M-PEM studies.

We have access to NHS prescriptions data through a longstanding arrangement with NHS Business Services and M-PEM is well-supported by GPs. Through the use of enhanced customized data collection questionnaires, M-PEM expands the range of applications, which include more detailed characterization of real-life drug use, adherence to prescribing recommendations and targeted analysis of events requiring special monitoring by regulatory authorities. A particularly useful application is the evaluation of the safety of a medicine in special populations or subgroups (e.g. patients switching from another therapy or patients with a particular risk factor) or following important changes in the product’s lifecycle (e.g. a licensing or formulation change). M-PEM studies therefore have an important contribution to make to pharmacovigilance and the risk management of medicines by providing valuable information on the use of new medications under real-life situations.


Approval to use patient-identifiable information

The DSRU has successfully applied for permission from the Ethics and Confidentiality Committee of the NHS National Information Governance Board to use patient-identifiable data without patient consent. This approval was granted under section 251 of the NHS Act 2006 which permits the temporary setting aside of the common law duty of confidentiality for the use of medical records for specific purposes. Section 251 approval is held by over 250 organisations, including medical charities, research institutes, universities, government and NHS bodies, where the nature of their work renders it impossible or impractical to obtain consent from every patient. Strict data security measures must be put in place by the applicant before approval is granted and annual reviews must be submitted to maintain approval once granted. Specifically, this allows the DSRU to use data from NHS prescriptions to conduct M-PEM studies. The MHRA (UK drug regulator), may license a new medicine on condition that the manufacturer agrees to commission a safety study by the DSRU.

GMC endorsement

In recognition of the importance of GPs completing and responding to M-PEM questionnaires that they receive, the General Medical Council (GMC) has published prescribing guidance urging GPs to respond DSRU questionnaires. The GMC’s guidance entitled “Good practice in prescribing and managing medicines and devices”, published in 2013, states,

You should respond to requests from the Drug Safety Research Unit for prescription-event monitoring data and information for studies on specific safety or pharmacovigilance issues.

Please contact us for an informal discussion.

Over 120 PEM and M-PEM studies have been conducted by the DSRU. Below are some recent M-PEM study publications. Please see the publications page for further references.