Use of the New Zealand Intensive Medicines Monitoring Programme to study the levonorgestrel-releasing intrauterine device (Mirena).

PURPOSE: To demonstrate how the Intensive Medicines Monitoring Programme (IMMP) can be used to monitor adverse events associated with an intrauterine device, using the levonorgestrel-releasing intrauterine device (Mirena) as an example.

METHODS

A long-term prospective observational cohort study using Prescription Event Monitoring (PEM) is currently being undertaken in women using Mirena in New Zealand. This report describes the method used and reports the early results for those women who used the device between March 1998 and March 2001. Adverse events were recorded by inserting doctors and general practitioners on registration forms and systematic follow-up questionnaires.

RESULTS

Between March 1998 and March 2001, the IMMP received 3519 registration forms for insertions in 3452 women. 'Difficult insertion' was the most frequently reported event (3.6% of all insertions). Approximately, 2% of the Mirena insertions were carried out under GA and there were three uterine perforations (0.9 per 1000 insertions) in the total cohort. To date, follow-up questionnaires have been processed for 495 patients. The response rate for these was 83%.

CONCLUSION

As adapted in the IMMP, PEM is an effective tool for the early post-marketing surveillance of an intrauterine device in real life clinical practice.