Prescription Data

PRESCRIPTION DATA

The data elements normally captured from the prescription information are summarized in Table 25.3. There may be variations on the type of data captured for particular medicines.

The continuous prescription records obtained by the IMMP are very useful for studying how specific medicines are used. For medicines not continually administered, it is possible to identify how many courses of treatment patients have and how long each course is. Recently, patterns of use of the weight reduction medicine sibutramine have been examined. The majority of the cohorts (59% of patients) had a treatment period of 90 days or less, suggesting mainly short-term use, although 11% were prescribed sibu-tramine for more than 1 year. Of the 2093 patients (12% of the cohort) who received more than one course of sibutramine, the mean duration between courses was 9 and 10 months, suggesting seasonal use of this medicine in NZ.

PATIENT IDENTIFICATION

It is essential that the IMMP correctly identifies each patient in the cohorts to avoid errors in the data (e.g. duplications) and to accurately obtain follow-up information. The IMMP has always used patients’ names, date of birth and address for identification (Table 25.3). However, in NZ, an increasing proportion of patients have a unique National Health Identification (NHI) number. Currently, the IMMP is able to identify the NHI number for at least 80% of patients (over 90% for the COX II inhibitor cohorts). This not only assists in checking each patient’s identification but also gives the potential for record linkage to national morbidity and mortality databases (see DATA LINKAGE).

ENHANCING PRESCRIPTION DATA CAPTURE

As described above, prescription records are received mostly as hard copy directly from individual pharmacies (currently 927 pharmacies) around NZ. Prescription and patient records are then entered into the computer database manually. This has resulted in very accurate and high-quality data but has often taken considerable time and resource – especially for larger cohorts.

Electronic capture of the prescription data (as done in the UK PEM scheme) has been considered by the IMMP in the past, but has not proved possible for vari-ous reasons including the lack of a complete centralised database of all prescriptions (see above) and insufficient resource. However, there have recently been proposals to include NHI numbers on all prescriptions and this may ultimately enable the IMMP to establish electronic capture of prescription data. It would be a great enhance-ment to PEM in NZ be able to establish cohorts quickly – and perhaps not just for new medicines – when safety issues arise. Therefore, the IMMP is currently review-ing its methods of data collection again, with the aim of moving towards a less paper-based system. However, there are obviously costs associated with such enhance-ments, and funding for the IMMP has been under threat in recent times (Herxheimer, 2004). Development of the IMMP systems will therefore depend on securing adequate funding to allow enhancements to be made whilst protecting the currently high standard of data collection.