Identification of Events

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Chapter: Pharmacovigilance: PEM in New Zealand

The IMMP methodology is unique in that events in patients taking the monitored medicines are identified from several different sources.


IDENTIFICATION OF EVENTS

DEFINITION

The IMMP definition of an event is similar to that used in PEM in the UK (Chapter 24) – any new clin-ical experience since the patient started the medicine, whether the event is thought to be drug related. This definition incorporates several possible clinical outcomes which are summarized in Table 25.4.


INTENSIVE METHODOLOGY FOR IDENTIFYING EVENTS

The IMMP methodology is unique in that events in patients taking the monitored medicines are identified from several different sources. The primary method is by follow-up questionnaires to patients’ doctors (as in UK PEM), but the IMMP also identifies adverse events from spontaneous reporting, from duplicate prescriptions, from other pharmacy data and also from data linkage to national morbidity and mortality databases. This intensive methodology for identifying adverse events is described in this section.

FOLLOW-UP QUESTIONNAIRES

Questionnaires seeking information on adverse events are sent to patients’ doctors at regular intervals. Most often this is the patient’s general practitioner (GP) but may be another prescribing doctor, includ-ing specialists. Doctors are asked to record all new clinical events (Table 25.4) in the patient’s notes from a specified date. For a new patient, this will usually be from the commencement of therapy, but if questionnaires have been sent previously, doctors are requested to record events from the date of the last received questionnaire (this date is given to facilitate record searching). For drugs used inter-mittently or if there is no follow-up information in the notes, the doctor (or practice nurse) may contact the patient directly to obtain the information required.

The compliance rate for returning IMMP ques-tionnaires has always been very high (greater than 80% for many medicines) and is currently around 70%. This average response rate is higher than that normally obtained in the UK PEM programme and may be related to several factors, including the high spontaneous reporting rate observed in the NZ (Olsson, 1999). Doctors are not paid for complet-ing the questionnaires, but they are now able to claim Continuing Medical Education (CME) points for completed forms.

SPECIFIC QUESTIONNAIRES

Whilst all IMMP follow-up questionnaires have simi-lar core elements (e.g. patient, prescription and doctor details) and are designed primarily to obtain infor-mation on adverse events, each questionnaire for a specific medicine is designed according to other outcomes of interest. Thus, questionnaires for intra-uterine devices (IUDs) included questions about preg-nancies and for sibutramine included questions on body mass index (BMI). Some questionnaires (e.g. for antipsychotic medicines) have sought information on indication for use of the medicine and concurrent medications. All questionnaires request information on the cessation of therapy and reasons for stopping treatment.

SUPPLEMENTARY QUESTIONNAIRES

It is sometimes necessary to obtain additional informa-tion to that obtained from the standard questionnaires described above. Examples include

Baseline and serial liver function tests for tolcapone.

Asthma severity questionnaire for salmeterol and eformoterol.

Results of endoscopy checks for omeprazole.

Questions about previous history of peptic ulcer disease for the COX II inhibitors.

If pregnancies are reported on the standard ques-tionnaires (questions are incorporated for women of child-bearing age), then further information is sought regarding the outcome of the pregnancy. For reported deaths, further information on the cause of death and possible relationship with the medicine is sought by further questionnaires and also by linkage to mortality databases (see DATA LINKAGE).

DUPLICATE PRESCRIPTIONS

During the 1980s, the IMMP developed duplicate prescription pads to enhance event reporting. In partic-ular, regions of NZ (covering about 25% of the popu-lation) personalized prescription pads were given to GPs, private specialists and hospitals (printed with the name of the hospital). Doctors gave the origi-nal and copy of the prescription to the patient who took both to the pharmacist, and then the accumu-lated copies were sent to the IMMP. An early study showed that the event-reporting rate in the duplicate prescription region was 14 times greater than that in a non-duplicate region (Coulter, 1986). This is because on duplicate prescription forms prescribers are asked to record any adverse events at the time of the consultation (Coulter, 1998) thus increasing the number of event reports received by the IMMP. The IMMP prescription pads have now become supplanted by electronic prescribing. Computer software for prac-titioners flags the monitored medicine and prints out a duplicate prescription whenever a monitored medicine is prescribed.

INTENSIFIED SPONTANEOUS REPORTING

Spontaneous reports sent to the NZ Pharmacovigi-lance Centre currently comprise about 12% of the total reports received for IMMP medicines. These ‘yellow card’ reports may come from health professionals, patients/carers or pharmaceutical companies. They are often of great value as they highlight a specific clini-cal concern and may form the index case for a series being considered as a signal.

Doctors and other health professionals in NZ are made aware which medicines are being monitored by the IMMP via listings in the Ministry of Health publication Prescriber Update and in the MIMS Cata-logue (the latter is linked to most patient management systems). In addition, drug companies are required to state that their medicine is being monitored by IMMP in all company product information, and visiting company representative are asked to remind doctors. The inclusion of a medicine in the programme should thus increase the spontaneous reporting rate, and an early study of betaβ-blockers showed this to be the case (Coulter and McQueen, 1982).

The symbiotic relationship between the IMMP and the NZ spontaneous reporting programme (CARM) is much valued as both programmes benefit from work-ing together in the same national pharmacovigilance unit. This is a key difference to the UK PEM scheme, which operates entirely separately to the UK sponta-neous reporting scheme.

DATA LINKAGE

In NZ, there are national databases containing infor-mation on births, deaths, hospital admissions and other morbidity outcomes, e.g. cancer. Identification of patients in these databases is by their unique NHI number, which – as discussed earlier – is now avail-able for the vast majority of patients. It is therefore possible to obtain mortality and morbidity data for patients in the IMMP cohorts by record linkage to these databases. This has proved very useful for iden-tifying which patients have died whilst taking a moni-tored medicine, and additional information is routinely sought on the cause of death. In addition to enabling the identification of events that may not be picked up from other sources, data linkage also offers great opportunity for other pharmacoepidemiology stud-ies of patients in the IMMP cohorts (see SPECIFIC STUDIES USING INTENSIVE MEDICINES MONI-TORING PROGRAMME DATA).


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