Because unintended pregnancies account for almost half of all pregnancies in the United States,1 investigation into new methods of contraception intended to improve compliance is essential. Although combined oral contraceptive pills (OCPs) have been a mainstay in fertility management for several decades, their efficacy relies on daily pill intake, which may be difficult for some patients to adhere to.2 The contraceptive vaginal ring, however, is inserted into the vagina by the woman herself and only needs to be changed once a month.
Many clinicians are reluctant to offer the contraceptive vaginal ring to patients they believe would be uncomfortable touching their own genitalia, particularly those who do not use tampons. In a randomized trial, Schafer et al3 found that neither tampon use nor patients' discomfort with touching their own genitalia predicted dissatisfaction or discontinuation of the contraceptive vaginal ring. Given the paucity of published data addressing patient comfort with vaginal contraceptive methods and tampon use, we proposed an analysis to estimate the association between tampon use and choice of the contraceptive vaginal ring or OCPs in participants of the Contraceptive Choice Project. We hypothesized that women who used tampons would be more likely to select the ring compared with OCPs, even after we controlled for other demographic and reproductive characteristics.
MATERIALS AND METHODS
We performed a cross-sectional analysis of baseline demographic data obtained during participant enrollment in the Contraceptive Choice Project. The Contraceptive Choice Project is a prospective, observational study designed to promote the use of long-acting reversible methods of contraception and to evaluate use, satisfaction, and continuation across both long-acting reversible methods of contraception and other methods in a cohort of 10,000 women. Women are offered counseling, reversible contraception of their choice, and sexually transmitted infection screening and treatment and are followed up for 3 years with telephone interviews. The enrollment phase began on August 1, 2007, and is projected to occur over 4 years. The Choice protocol was approved by the Washington University School of Medicine Human Research Protection Office before initiation of participant recruitment.
Women learn of the Contraceptive Choice Project through information posted in selected St. Louis area clinics and by word of mouth. Eligibility screening occurs in person at recruitment sites or on the telephone by calling the main Choice telephone number. Screening encounters are conducted by a trained staff person who asks a series of questions to determine eligibility. Inclusion criteria are age 14–45 years, residence in the St. Louis city or county or seeking services at designated recruitment sites, willingness to switch or initiate a new contraceptive method, sexual activity with a male partner within 6 months, and ability to consent in English or Spanish. Women who are surgically sterile or desire pregnancy within 1 year are excluded. If the woman is an eligible candidate, the screener offers the opportunity to enroll. This encounter is documented on a standardized data collection form.
Enrollment in Choice occurs during an in-person session. Informed consent for participation in Choice is only obtained after the woman has completed contraceptive counseling. The decision to obtain informed consent for the study after contraceptive counseling was made based on the recommendation of our human research projection office colleagues. Contraceptive counseling is provided to women before study enrollment in the Choice Project by either 1) staff employed by the community-based recruitment clinic as part of the woman's routine family planning or gynecology visit or 2) trained contraceptive counselors at the university-based recruitment site. Each woman receives counseling according to protocols established by each clinic and includes identifying a method that is appropriate for her and available through the Choice Project. Questions, misinformation, and other concerns the potential participant may have are addressed at this time to facilitate her informed decision-making process. After counseling, she undergoes the informed consent process for the research study, which focuses on the follow-up surveys to assess method continuation and satisfaction.
The study counselor collects clinical information on each woman using a standardized form to identify contraindications or conditions that may influence use of a particular contraceptive method. Approval for the method is obtained from a clinician at the end of contraceptive counseling.
For minors younger than 18 years, their assent and the consent of one parent or legal guardian are obtained. In situations where the minor does not know the whereabouts of her parent or legal guardian or where it would not be in the minor's best interest to contact the parent or legal guardian, institutional review board approval to waive parental consent has been obtained.
The data for this analysis were collected in the baseline questionnaires of the first 2,419 participants. The enrollment of this cohort was completed in December 2008. Our original questionnaire did not contain a question about tampon use; this question was later added. It asked participants whether, during their periods, they used tampons all the time, more than half the time, or less than half the time, or did not use tampons. For the purpose of this analysis, these categories were collapsed into two categories: tampon use yes if participants answered “all the time,” “more than half the time,” or “less than half the time,” and tampon use no if they responded “don't use tampons.” All participants in this analysis were from the women enrolled who had a response to the tampon use questionnaire and chose either the contraceptive vaginal ring or OCPs (Fig. 1). Demographic information obtained included age, race, Hispanic ethnicity, education, marital status, income, insurance status, age at menarche, gravidity, parity, and body mass index (underweight, less than 18.5; normal, 18.5–24.9; overweight, 25.0–29.9; obese, 30.0 kg/m2 or greater). Sexual history information obtained included the number of sexual partners in the previous 30 days, condom use and perceived partner willingness to use condoms, ever contraception use and previous contraception choices, and douching activity. Information about factors contributing to method choice was also obtained, including cost, effectiveness, recommendation by other physicians and friends, ease of use, approval by sexual partner, safety, and side effects.
Demographic characteristics were described using frequencies, percentages, and means. Possible differences between the two groups were analyzed using χ2 tests, t tests, and Fisher exact tests. Multivariable Poisson regression models with robust error variance were used to estimate relative risk (RR) and 95% confidence interval (CI) for the relationship between method choice and tampon use. This analytic approach provides an unbiased estimate of the RR when the outcome is common (greater than 10%).4,5 Covariates considered in the adjusted multivariable analysis include current condom use, ever vaginal ring use, cost of contraceptive method, knowledge of effectiveness of OCPs, age, education, and recent pill use. A P value of less than .05 was used to define statistical significance. All analyses were performed with the use of SAS 9.2 (SAS Institute Inc., Cary, NC). Preliminary analysis of Choice data showed an 11% overall acceptance rate of the contraceptive vaginal ring. Based on this information, we assumed a contraceptive vaginal ring acceptance rate of 10% in women not using tampons, and we considered an RR of 2.5 for contraceptive vaginal ring in tampon users to be clinically relevant. We calculated a sample size of 112 per group with 80% power (α=.05) based on these assumptions.
Of the first 2,419 participants, 284 (12%) chose the contraceptive vaginal ring and 302 (12%) chose OCPs as their baseline method of contraception. The tampon question was asked of 1,356 women, with 1,035 (76%) participants reporting tampon use. Of the 1,035 participants who reported tampon use, 133 (13%) chose the contraceptive vaginal ring and 114 (11%) chose OCPs. Of the 321 participants who did not use tampons, 23 (7%) chose the contraceptive vaginal ring and 41 (13%) chose OCPs (P=.01).
In our subset for this analysis (Table 1), 311 participants chose either the contraceptive vaginal ring (n=156) or OCPs (n=155), and 247 (79%) reported tampon use. Of the 247 tampon users who selected OCPs or the contraceptive vaginal ring, 133 (54%) chose the contraceptive vaginal ring. Of the 64 participants not using tampons, 23 (36%) chose the contraceptive vaginal ring. Most participants were younger than 25 years (69%), single (75%), and nulliparous (72%). White and African-American participants were similarly represented. More than half the participants had insurance (57%), whereas 37% did not have any insurance and 7% had Medicaid. Almost half the participants had a body mass index of 18.5–24.9, indicating a normal weight. Most of the other half was overweight or obese (23% and 22%, respectively).
In the univariable analysis comparing choice of the contraceptive vaginal ring or OCPs, tampon users were more likely to choose the contraceptive vaginal ring over OCPs (54% compared with 46%). Non–tampon users were more likely to choose OCPs instead of the contraceptive vaginal ring (64% compared with 36%). When we controlled for current condom use, ever use of the contraceptive vaginal ring, method cost, age, education, and knowledge of birth control pill effectiveness (Table 2), tampon users were 34% more likely to choose the contraceptive vaginal ring (RR 1.34, 95% CI 1.01–1.78). Condom use was associated with a reduced likelihood of contraceptive vaginal ring use compared with OCPs in the univariable analysis and adjusted analysis (RR 0.75, 95% CI 0.61–0.93). Participant concern about cost was negatively associated with contraceptive vaginal ring choice (RR 0.55, 95% CI 0.35–0.86), and participants who correctly estimated the effectiveness of OCPs were more likely to choose the contraceptive vaginal ring (RR 1.26, 95% CI 1.01–1.57). Although women with greater education seemed more likely to choose the contraceptive vaginal ring over OCPs, education did not remain a statistically significant factor in the multivariable analysis (RR 1.31, 95% CI 0.97–1.76). Additionally, age was not associated with contraceptive vaginal ring use in our multivariable analysis.
Most participants (79.5%) reported ever using birth control pills, whereas only some (17.2%) reported recent use. In contrast, far fewer women (28.6%) reported ever using the contraceptive vaginal ring, and even fewer (8.6%) reported recent use. Ever contraceptive vaginal ring users were more likely to choose the contraceptive vaginal ring (RR 1.96, 95% CI 1.60–2.40).
In this analysis, we found that tampon users were more likely to choose the contraceptive vaginal ring as their baseline contraceptive method, whereas women who did not use tampons were more likely to choose OCPs. Although we found an association between tampon use and method selection, Schafer et al3 found that tampon use was not predictive of continuation and satisfaction with the contraceptive vaginal ring. It is important to note that their study was a randomized controlled trial where method was randomly assigned; therefore, correlates of method selection could not be ascertained.
In addition to tampon use, familiarity with contraceptive methods may influence a woman's method selection within the Choice Project. Most participants answering the tampon question had previously used some form of contraception, and most had prior experience with OCPs. Almost a third of participants in this data set had used the contraceptive vaginal ring in the past. Our finding that prior users of the contraceptive vaginal ring were twice as likely to choose the contraceptive vaginal ring may indicate a high acceptability and satisfaction with this method and is consistent with prior acceptability studies. Dieben et al6 found an overall satisfaction rate of 85%, and 90% of their participants planned to recommend the contraceptive vaginal ring to friends.
We also found that condom use was negatively associated with choosing the contraceptive vaginal ring among our participants. Roumen et al7 found that almost 20% of their study participants noted feeling the ring during intercourse. It is possible that having two objects in the vagina at the same time may be physically or psychologically uncomfortable to the woman or her partner.
Because women in this study could choose any method without having to worry about cost, we observed approximately the same percentage of women choosing to use the contraceptive vaginal ring (11%) or OCPs (12%). However, in the real world, these two methods vary significantly in cost, including the out-of-pocket expense paid by women. The contraceptive vaginal ring is significantly more costly than generic OCPs, and we did observe a 50% reduction in the choice of the contraceptive vaginal ring among participants who perceived cost as a factor.
Our study is not without limitations. Our analysis only investigated predictors of baseline uptake of contraceptive method and does not answer the question of whether tampon use is predictive of contraceptive vaginal ring continuation and satisfaction. Satisfaction with a contraceptive method is important because up to 31% of women will discontinue their reversible contraceptive method within 6 months of initiation.8 Although prior research found that tampon use is not predictive of continuation or satisfaction,2 future analyses of the Choice Project may find that tampon use and ability to select the contraceptive method may influence both satisfaction and continuation with the contraceptive vaginal ring.
The contraceptive vaginal ring is an effective contraceptive method with reported high satisfaction and continuation. Our study suggests that information about tampon use is one of the factors in a woman's decision to use the contraceptive vaginal ring and could be considered during discussions with her medical provider. Tampon use should not be the only criterion on which recommendation or prescription of the contraceptive vaginal ring is based.
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© 2010 The American College of Obstetricians and Gynecologists
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