The Effect of Age, Parity and Body Mass Index on the Efficacy, Safety, Placement and User Satisfaction Associated With Two Low-Dose Levonorgestrel Intrauterine Contraceptive Systems: Subgroup Analyses of Data From a Phase III Trial

Abstract

Objective: Two low-dose levonorgestrel intrauterine contraceptive systems (LNG-IUSs; total content 13.5 mg [average approx. 8 μg/24 hours over the first year; LNG-IUS 8] and total content 19.5 mg [average approx. 13 μg/24 hours over the first year; LNG-IUS 13]) have previously been shown to be highly effective (3-year Pearl Indices: 0.33 and 0.31, respectively), safe and well tolerated. The present subgroup analyses evaluated whether or not outcomes were affected by parity, age (18-25 vs 26-35 years), or body mass index (BMI, <30 vs ≥30 kg/m2).

Methods: Nulliparous and parous women aged 18‒35 years with regular menstrual cycles (21‒35 days) requesting contraception were randomized to 3 years of LNG-IUS 8 or LNG-IUS 13 use.

Results: In the LNG-IUS 8 and LNG-IUS 13 groups, 1432 and 1452 women, respectively, had a placement attempted and were included in the full analysis set; 39.2%, 39.2% and 17.1% were 18-25 years old, nulliparous and had a BMI ≥30 kg/m2, respectively. Both systems were similarly effective regardless of age, parity or BMI; the subgroup Pearl Indices had widely overlapping 95% confidence intervals. Placement of LNG-IUS 8 and LNG-IUS 13 was easier (p < 0.0001) and less painful (p < 0.0001) in women who had delivered vaginally than in women who had not. The complete/partial expulsion rate was 2.2-4.2% across all age and parity subgroups and higher in parous than in nulliparous women (p = 0.004). The incidence of pelvic inflammatory disease was 0.1-0.6% across all age and parity subgroups: nulliparous and younger women were not at higher risk than parous and older women, respectively. The ectopic pregnancy rate was 0.3-0.4% across all age and parity subgroups. Across all age and parity subgroups, the 3-year completion rate was 50.9-61.3% for LNG-IUS 8 and 57.9-61.1% for LNG-IUS 13, and was higher (p = 0.0001) among older than younger women in the LNG-IUS 8 group only.

Conclusions: LNG-IUS 8 and LNG-IUS 13 were highly effective, safe and well tolerated regardless of age or parity.

Trial registration: Clinical trials.gov NCT00528112.

Conflict of interest statement

Competing Interests: The authors of this manuscript have read the journal's policy and have the following competing interests: Kristina Gemzell-Danielsson occasionally serves on advisory boards and has been an invited speaker at scientific meetings for Bayer AG, MSD/Merck, HRA Pharma, ExcelGyn and Gideon Richter on an ad hoc basis. Her institution has received grants for conducting the Phase II and Phase III clinical trials of the 13.5 mg and 19.5 mg levonorgestrel intrauterine contraceptive systems. Dan Apter’s institution has received grants from Bayer Healthcare for conduct of the Phase II and Phase III trials of the 13.5 mg and 19.5 mg levonorgestrel intrauterine contraceptive systems. He has also taken part in advisory boards and has been an invited speaker at scientific meetings for Bayer AG, MSD/Merck, HRA Pharma, and Gideon Richter on an ad hoc basis. Brian Hauck’s institution has received grants for conduct of the Phase II and Phase III clinical trials of the 13.5 mg and 19.5 mg levonorgestrel intrauterine contraceptive systems. He has served on advisory boards and is currently a speaker for Merck, Bayer Healthcare and Pfizer. Thomas Schmelter and Sarah Rybowski are full-time employees of Bayer Pharma AG. Kimberly Rosen is a full-time employee of Bayer HealthCare Pharmaceuticals. Anita Nelson has received honoraria for serving on speakers’ bureaus and advisory boards for Bayer HealthCare. Her clinic has received grant funding for conduct of this Phase III study from Bayer HealthCare. Kristina Gemzell-Danielsson confirms that she is a PLOS ONE Associate Editor and this does not alter the authors' adherence to PLOS ONE editorial policies and criteria.

Figures

Fig 1. (A) Investigators’ assessment of ease of placement (both treatment groups combined); (B) Subjects’ assessment of pain of placement (both treatment groups combined).