Original research articleFactors associated with nonadherence to instructions for using the Nestorone®/ethinyl estradiol contraceptive vaginal ring☆
Introduction
Efforts to increase global access to contraception have led to overall decreases in unintended pregnancy rates, yet 40% of pregnancies worldwide continue to be unintended [1]. In the United States, contraceptive failures account for 41% of unintended pregnancies [2] and occur mainly with user-dependent methods [3], [4]. Long-acting reversible contraceptives (LARCs) eliminate the user-dependence variable and can greatly reduce unintended pregnancy rates [4]. When cost, access and knowledge barriers are removed, a majority of women who have chosen LARCs report high satisfaction and continuation rates [5].
Access to LARCs, however, requires the availability of skilled providers for insertions and removals and entails high up-front costs. These barriers contribute to underutilization of LARCs, especially in low-resource settings [6], [7]. Targeted investments and initiatives to increase LARC uptake in low-income countries have generally shown high user satisfaction and continuation rates [8], [9], but such measures have not yet yielded significant increases in LARC use or to changes in the contraceptive method mix [6].
Recently, vaginal rings have gained increasing attention as a promising technology to diversify and add to the method mix for both contraceptive use and prevention of sexually transmitted infections (STIs) [10]. Contraceptive, microbicide and multipurpose vaginal rings are new developments that may allow women to have control over pregnancy timing and prevention of STI transmission. These products may even be useful for women in settings where they have limited power to negotiate the terms of sexual relationships [11].
In this context, the Population Council developed a contraceptive vaginal ring (CVR) containing Nestorone® (segesterone acetate) and ethinyl estradiol (NES/EE) and is reusable for 1 year. The ring releases 150 mcg of NES and 15 mcg of EE daily and is designed for use on a 21/7-day regimen for 13 cycles. It does not require skilled providers for insertion or removal, does not require refrigeration and may have global appeal for women who value using one device for a longer period of time while remaining in control of their contraception. Results of an acceptability study of the NES/EE CVR indicated that women were highly satisfied with this contraceptive method and found it easy to use [12].
As a user-dependent method, however, the NES/EE CVR requires adherence to instructions for use to maintain contraceptive effectiveness. Accordingly, we sought to evaluate factors associated with nonadherence. We also explored the extent to which nonadherence predicts method dissatisfaction, early discontinuation and pregnancy.
Section snippets
Study design and population
This study draws on data collected during a Phase 3 clinical trial of the NES/EE CVR and from a previously published acceptability study conducted within that trial [12]. The trial was conducted at 12 sites in the United States, Latin America, Europe and Australia from 2006 to 2009. Participants were healthy, sexually active women 18–40 years old. Exclusion criteria included medical contraindications to combined hormonal contraceptive use; body mass index >29 kg/m2; cystocele, rectocele or any
Results
Of 1135 participants enrolled in the study, 1036 completed acceptability questionnaires (91%). We excluded participants from the analysis if they discontinued the study for non-ring-related reasons (84) or were lost to follow-up (47). We analyzed questionnaires for 905 participants, 706 (78%) of whom completed the clinical trial and 199 (22%) discontinued the study early due to ring-related reasons. Of the 905 participants included, 803 (88.7%) completed the survey at time 1 and time 2, while
Discussion
In this study, we examined factors associated with nonadherence to instructions for use of a novel CVR reusable for up to 1 year as measured by ring removals >2 h outside scheduled removal periods. We found that 13% of women reported such removals, and those who did had almost twice the odds of being dissatisfied with the ring and discontinuing its use early. They also had four times the odds of becoming pregnant during the study. These findings are similar to continuation data for NuvaRing®
Acknowledgments
We would like to acknowledge the following individuals for their contribution to the conduct of the clinical trial: All Principal Investigators from the 300B study including: Dr. Daniel Apter, Dr. Luis Bahamondes, Dr. Horacio Croxatto, Dr. Gyorgy Bartfai, Dr. Melissa Gilliam, Dr. Antonia Nicosia, Dr. Philip Darney, Dr. Jody Steinaur, Dr. Christina Gemzell, Dr. Ian Fraser, Dr. Edith Weisberg, Lic. Vivian Brache, Dr. David Portman, Dr. Erica Banks, Dr. Maria Jose Miranda and the late Dr. Daniel
Disclosures
C.S.V. has served on the Medical Advisory Boards for Merck and Bayer and has given ad hoc invited lectures for Merck and Bayer. The other authors have no conflicts of interest to disclose.
Funding source
This study was supported by the National Institutes of Health/NICHD (grant #: 3RO1HD047764-02S2); and the US Agency for International Development (USAID) (grant #: GPO-A-00-04-00019).
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Clinical Trial Registration Number: NCT00263341.