UC Davis

Background

Extending hormonal intrauterine system duration will allow users to have less need for procedures to provide long-term contraception.

Objective

This study aimed to evaluate the efficacy and safety of the levonorgestrel 52 mg intrauterine system during years 7 and 8 of use.

Study design

A total of 1751 nulliparous and multiparous participants aged 16 to 45 years enrolled in a phase 3, multicenter trial to evaluate the efficacy and safety of the use of the Liletta levonorgestrel 52 mg intrauterine system for up to 10 years. Participants aged 36 to 45 years at enrollment underwent safety evaluation only. After the first year, we evaluated participants every 6 months for intrauterine system location confirmation and urine pregnancy testing at each visit. We assessed the Pearl Indices in years 7 and 8 and the life-table analysis for cumulative pregnancy rates through 8 years of use. For the primary efficacy analyses, all participants aged 16 to 35 years at enrollment were included through year 6; years 7 and 8 included only users aged ≤39 years at the start of each use year. Safety outcomes were assessed in all participants regardless of duration of use. We assessed amenorrhea rates, defined as no bleeding or spotting in the 90 days before the end of the year.

Results

After intrauterine system placement, we followed 1568 participants aged 16 to 35 years and 146 participants aged 36 to 45 years. The 16- to 35-year-old participants included 986 (57.5%) nulliparous and 433 (25.3%) obese users. Overall, 569 participants started year 7, 478 completed year 7 (380 aged ≤39 years at beginning of year) and 343 completed year 8 (257 aged ≤39 years at beginning of year); 77 completed 10 years of use. Eleven pregnancies occurred over 8 years, 7 (64%) of which were ectopic. Two pregnancies occurred in year 7 (Pearl Index, 0.49; 95% confidence interval, 0.06-1.78), 1 in a participant with implantation 4 days after a desired removal; no pregnancies occurred in year 8. The cumulative life-table pregnancy rate in the primary efficacy population through year 8 was 1.32 (95% confidence interval, 0.69-2.51); without the postremoval pregnancy, the rate was 1.09 (95% confidence interval, 0.56-2.13). Two perforations (0.1%) occurred, none noted after year 1. Expulsion occurred in 71 (4.1%) participants overall, with 3 in year 7 and 2 in year 8. Pelvic infection was diagnosed in 16 (0.9%) participants during intrauterine system use, 1 each in years 7 and 8. Only 44 (2.6%) participants overall discontinued because of bleeding complaints (4 total in years 7 and 8) with rates per year of 0.1% to 0.5% for years 3 to 8. Amenorrhea rates were 39% at both years 7 and 8.

Conclusion

The levonorgestrel 52 mg intrauterine system is highly effective over 8 years of use and has an excellent extended safety profile. This report details the longest period of efficacy and safety data for continuous use of a levonorgestrel 52 mg intrauterine system for contraception.