Insertion of intrauterine devices: a comparison of experience with Mirena and Multiload Cu 375 during post-marketing monitoring in New Zealand.

AIM: To compare the incidence of reported insertion problems with the levonorgestrel-releasing intrauterine device (Mirena) with that of the copper device Multiload Cu 375.

METHODS

Prescription Event Monitoring (PEM) methodology, as used in the Intensive Medicines Monitoring Programme, was used to identify cohorts of women and record events associated with insertion.

RESULTS

Data were analysed from 16 159 women receiving Multiload Cu 375 between 1991 and 2001, and 3452 women receiving Mirena between 1998 and 2001. Difficult insertion was reported more often with Mirena (RR= 2.7, 95% CI = 2.2--3.3, p <0.0001). Stratified analyses suggested this was not explained by the presence of more nulliparous women in the Mirena cohort or the non-contraceptive indications for use of Mirena. Mechanical problems with the device were reported in about 1% of Mirena insertions compared with 0.01% of Multiload Cu 375 insertions and this difference was significant (p <0.001). About 2% of Mirena insertions were performed under general anaesthetic compared with 0.1% of Multiload Cu 375 insertions. Adverse reactions to insertion, including pain and vaso-vagal reaction, were more frequent with Mirena than with Multiload Cu 375 (p <0.001).

CONCLUSIONS

During the period of study, insertion of Mirena was more difficult and was associated with more device problems and adverse reactions than insertion of Multiload Cu 375.