Satisfaction and continuation rates of common forms of contraception in the United States are disappointing. According to the most recent National Survey of Family Growth, 28% of women using contraceptives in the United States take the oral contraceptive pill (OCP).1 However, continuation rates for OCPs are reported to be as low as 29% at 6 months.2 Rosenberg and Waugh found that women who discontinued OCPs often do not begin a new contraceptive method or changed to less effective contraceptive options.3 The 6-month continuation rate for depot medroxyprogesterone acetate (DMPA) was recently found to be 36–48%,4 and studies cite a 12-month continuation rate as low as 23–28%.5,6 Contraceptive discontinuation will often result in unintended pregnancy.
Despite their proven safety, effectiveness, and cost-effectiveness, long-acting reversible contraceptive methods (intrauterine devices [IUDs] and the subdermal implant) are not widely used in the United States. In fact, only 5.5% of women taking contraceptives between the ages of 15 and 44 years use the IUD.1 Reasons for lack of use of these highly effective reversible methods include women's and provider's knowledge of and attitudes toward the methods; practice patterns among providers; myths and misconceptions regarding the side effects of these methods; high initial cost; and provider biases.7–11 Methods of long-acting reversible contraceptives are believed by many experts to have the highest continuation rates and high levels of satisfaction among all methods of contraception. However, longitudinal data assessing 12-month continuation rates and satisfaction of U.S. women using long-acting reversible contraceptive methods are lacking.
The purpose of this analysis is to estimate the 12-month continuation and satisfaction rates of long-acting reversible contraceptive method users in women enrolled in the Contraceptive CHOICE Project, and to compare these measures with women using the OCPs: the most common form of reversible contraception used in the United States. Our hypothesis was that women using long-acting reversible contraceptive methods would have higher levels of satisfaction and higher continuation rates than women using OCPs.
MATERIALS AND METHODS
The methodologic details of the Contraceptive CHOICE Project have been previously described.12 A brief description of the project and the analytic approach for this report are described below. The CHOICE protocol was approved by the Washington University in St. Louis School of Medicine Human Research Protection Office before the initiation of recruitment.
CHOICE is an observational cohort study developed to promote the use of methods of long-acting reversible contraceptives (specifically the subdermal implant and the IUD) in the St. Louis region. Our primary objective is to provide no-cost contraception to a large number of women in our region in an effort to reduce unplanned pregnancies. To accomplish these objectives, we sought to remove two major barriers to long-acting reversible contraceptive use: financial obstacles and lack of patient awareness of the safety and efficacy of these methods. By increasing the acceptance and use of long-acting reversible contraceptive methods, CHOICE seeks to reduce unintended pregnancy at the population level in our region.
CHOICE is a convenience sample of women in St. Louis City and County. Participants are recruited from clinics serving women at high risk for unplanned pregnancy and sexually transmitted infections (STIs), as well as from the local community including college students, graduate students, and personnel affiliated with Washington University and Barnes-Jewish Hospital. Recruitment occurs through general awareness about the CHOICE Project through medical providers, newspaper reports, study flyers, and word of mouth.
Inclusion criteria for CHOICE include 1) age 14–45 years; 2) not currently using a contraceptive method or willing to start a new reversible contraceptive method (may have used the chosen method previously, but not their current method of contraception); 3) no desire to conceive for at least 12 months; 4) sexually active with a male partner (or an intent to be active in the next 6 months); 5) reside in or seek clinical services in designated recruitment sites in the St. Louis region; and 6) ability to consent in English or Spanish. Women were excluded if they had a hysterectomy or sterilization procedure or were unwilling to try a new method. Additional inclusion criteria for this analysis include participants who completed the 12-month follow-up survey or provided information that they discontinued their contraceptive method before the survey and participants who received and initiated their baseline chosen method of contraception within 3 months of enrollment.
All potential participants in the CHOICE Project are read a standardized script regarding long-acting reversible contraceptive methods, regardless of whether or not they enroll in the project.12 All enrolled participants receive standardized contraceptive counseling. During counseling, all reversible contraceptive methods are presented and their associated levels of effectiveness, common side effects, risks, and benefits are described so that participants can make an informed decision. Each participant is provided reversible contraception at no cost for 3 years. After a comprehensive baseline interview and screening for sexually transmitted infections (Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, syphilis, and human immunodeficiency virus [HIV]), we prospectively follow all participants. We conduct telephone interviews at 3, 6, 12, 18, 24, 30, and 36 months after enrollment using standardized survey instruments. Participants are compensated with a $10.00 gift card for every completed follow-up survey.
In the baseline and follow-up survey instruments, we collect comprehensive information on demographic characteristics and reproductive history including contraceptive experience, sexual behavior including number and gender of sexual partners, and incident STI. The baseline survey is administered face-to-face in a private setting by trained study staff. We used the following definitions in the survey: 1) public assistance (yes): if the participant responded that she currently receives food stamps, WIC, welfare, or unemployment; and 2) unintended pregnancy (yes): responded yes to “you wanted to be pregnant later or you didn't want to be pregnant then or any time in the future” when asked about a previous pregnancy. Research staff also collects and records clinically relevant data, including complaints, complications, side effects, method expulsions and removals, pregnancies, and outcomes from any problem visits or telephone calls.
At each follow-up survey, participants were asked the question “are you still using the method?” If the participant answered “yes,” she would be further asked “did you ever stop using the method?” A participant was considered a “continuer” if she reported using her baseline method at the 3-, 6-, and 12-month surveys without any temporary stop of 1 month or longer. We defined a “discontinuer” as those who reported not using the baseline method at any of the survey time points or reported any temporary stop of the method for 1 month or longer. For participants who failed to answer these questions, our method allocation log and pharmacy refill records were checked to confirm their status. We offered IUD replacement to women who experienced an expulsion (3.5%). When the IUD was replaced within a month and the participant was using the same method at 12 months, we considered this a “continuer.” If the participant elected not to have the same IUD replaced, she was considered a “discontinuer.” Participants who were lost to follow-up were censored at their last completed survey date. Satisfaction level was evaluated on the continuers at 12 months. Satisfaction was categorized in three levels: “very satisfied,” “somewhat satisfied,” and “not satisfied.” All participants who discontinued their method by 12 months were considered “not satisfied.” We grouped “very satisfied” and “somewhat satisfied” together as “satisfied” in the modeling (multivariable) stage of the analysis. We calculated 12-month continuation rates and also levels of satisfaction of all contraceptive methods. Individual methods were compared with OCP users, because OCPs are the most commonly used reversible contraceptive method in the United States.1 We also grouped participants as long-acting reversible contraceptive users and users of other contraceptive (non–long-acting reversible contraceptive) methods in our analysis.
To describe demographic characteristics of the study participants, frequencies, percentages, means, and standard deviations were used for appropriate data type. To compare these baseline covariates among different method users, χ2 and Fisher exact tests were performed when appropriate for categorical variables, as well as the Student t test for continuous normally distributed variables. Normality was assessed by evaluating the histogram of continuous variables. To compare the continuation among different method users, Kaplan-Meier survival curves were constructed to estimate the continuation rates, and Cox proportional hazard models were used to estimate the hazard ratios between methods. Proportional hazard assumptions were checked by plotting the log-log of survival probability. For the purpose of comparing the satisfaction rates among different method users, Poisson regression models with robust error variance were used to estimate relative risk (RR) and 95% confidence intervals (CIs). This analytic approach provides an unbiased estimate of the RR when the outcome is common (greater than 10%).13 Effect modification was checked by including an interaction term between the method and the covariate of interest in the model. Effect modification was detected if the interaction term was statistically significant at the prespecified alpha level. Confounding was defined as a greater than 10% relative change in the association between continuation–satisfaction and method choice with or without the covariate of interest in the model. Confounders were included in the final multivariable model. All analyses were performed using STATA 10. The significance level alpha was set at 0.05. We decided a priori to do an analysis of continuation rates after 5,000 participants were recruited and followed for 12 months. This sample size gave us adequate power (more than 90%) to detect a two-fold increase in discontinuation with OCPs compared with long-acting reversible contraceptive methods.
Of the first 5,087 women enrolled in CHOICE between August 2007 and December 2009, 4,936 reached their 12-month time point, and 4,167 met the inclusion criteria for this analysis. There were 3,016 women (72.4%) still using their baseline method at 12 months, 996 (23.9%) who discontinued, and 155 (3.7%) who were lost to follow-up. Table 1 presents the baseline demographic and reproductive characteristics of these 4,167 participants and the first 5,087 women enrolled into CHOICE. The characteristics of the subset are similar to the cohort overall. In our analytic sample, the mean age is 25 years; 47% are African American; 34% had a high school education or less; 33% receive public assistance; and 40% have trouble paying for basic necessities. Forty-eight percent are nulliparous, 66% experienced an unintended pregnancy, and 40% had an abortion.
Table 2 provides the baseline characteristics of our sample population by contraceptive method. Among women enrolled, more than two thirds (68.3%; 95% CI 66.9, 69.7) chose a long-acting reversible contraceptive method: 45% chose a levonorgestrel intrauterine system, 10% chose a copper IUD, and 13% chose the etonogestrel subdermal implant. With regard to non–long-acting reversible contraceptive methods, 8% chose DMPA, and 23% chose combined hormonal methods (11% OCPs, 10% vaginal ring, and 2% transdermal patch).
The baseline demographic and reproductive characteristics stratified by long-acting and non–long-acting methods can be found in Table 3. Compared with other contraceptive method users, long-acting reversible contraceptive users were older, were less educated, had higher BMI, were more likely to rely on public assistance, and have public insurance. They were also more likely to have higher parity, a greater number of unintended pregnancies and abortions, and a history of STI.
Continuation rates for long-acting reversible contraceptive methods ranged from 83 to 88%, with the highest continuation rate for the levonorgestrel intrauterine system (88%) and copper IUD (84%). Women using the implant also had very high rates of continuation at 1 year (83%). The difference in 12-month continuation rates between IUDs and the implant was not statistically significant (hazard ratio 1.23; 95% CI 0.97, 1.58), or clinically significant (87% compared with 83%, respectively). Twelve-month continuation rates for non–long-acting reversible contraceptive methods were as follows: 57% DMPA, 55% OCPs, 54% ring, and 49% patch. There were no significant difference in continuation between these non–long-acting methods.
For our survival analysis, we focused on discontinuation of contraceptive methods. Compared with long-acting reversible contraceptive users, users of non–long-acting methods were more likely to discontinue the use of their method at 12 months (45.3% compared with 13.8%; hazard ratio 4.11, 95% CI 3.61, 4.68; Table 4 and Fig. 1). OCP users had higher 12-month discontinuation rates than long-acting reversible contraceptive users (hazard ratio 4.13, 95% CI 3.48, 4.89). More specifically, OCP users had higher discontinuation rates than users of both IUDs and the implant (IUDs: hazard ratio 4.30, 95% CI 3.60, 5.14; implant: hazard ratio 3.49, 95% CI 2.70, 4.50). The most common reason for discontinuation of either IUD was bleeding or cramping or both; 14% of all copper IUD users and 5% of all levonorgestrel intrauterine system users reported discontinuing the method for these reasons. Additionally, 3% of levonorgestrel intrauterine system users reported discontinuation of the method because of side effects such as acne and weight change. The most common reason for discontinuation of the implant was unpredictable bleeding (10%).
Satisfaction rates for users of long-acting and non–long-acting reversible contraceptive methods are also shown in Table 4. These rates mirror the continuation rates. This is not unexpected, given that all discontinuers were considered “not satisfied” with their method. Satisfaction was highest for IUDs with more than 80% satisfied, of which 66–70% reported being very satisfied. Satisfaction with the implant was also quite high with 79% satisfied, of which 55% reported being very satisfied. Comparing long-acting and non–long-acting reversible contraceptive methods, we see that 84% of participants were satisfied with their method at 12-months, compared with 53% of participants using non–long-acting methods (RR=1.59; 95% CI 1.50, 1.68).
In the Cox proportional hazard model and the Poisson regression model, we evaluated a number of potential confounders that we believed could be associated with both the contraceptive method and continuation or satisfaction. Race or ethnicity, educational level, parity, body mass index (BMI), income, markers of socioeconomic status, and histories of unintended pregnancy, abortion, and STI were assessed, but none of these variables made a significant (more than 10%) change on the effect estimate. Thus, we present unadjusted hazard rate ratios and relative risks. Interestingly, when we evaluated continuation rates and satisfaction within each long-acting reversible contraceptive method stratified by age, the continuation of the levonorgestrel intrauterine system and implants did not vary by age. In women older than 20 years of age, 12-month continuation rates were 88% for levonorgestrel intrauterine system and 85% for the implant. This was very similar to the continuation rates in women age 20 years and younger (85% levonorgestrel intrauterine system and 80% implant). However, compared with women older than 20 years of age using the copper IUD, the copper IUD users younger than 21 years of age had a higher discontinuation rate (28% compared with 15%, hazard ratio 2.10, 95% CI 1.11, 4.02).
In the United States, there are 6 million pregnancies that occur each year, and approximately half are unintended.14 Among women who experience an unintended pregnancy, half report using a contraceptive method in the month when the pregnancy occurred.15,16 Because most women use a contraceptive method with adherence requirements, the majority of pregnancies result from incorrect or inconsistent method use rather than from method failure.17 To reduce the number of unintended pregnancies in the United States, clinicians should be offering the most effective methods of contraception to women as first-line options. Long-acting reversible contraceptive methods, including the IUD and the subdermal implant, are the most effective methods, forgettable, and not user-dependent. Thus, their “typical use” effectiveness is almost equal to “ideal” effectiveness.
Of the first 4,167 women completing their first 12 months of follow-up in the Contraceptive CHOICE Project, we found that long-acting reversible contraceptive methods have the highest continuation rates and highest levels of satisfaction. Among IUD users, there was higher uptake of the levonorgestrel intrauterine system; however, there was little difference in the rates of continuation and satisfaction between users of the levonorgestrel intrauterine system and the copper IUD. We are unsure why participants were four times more likely to choose levonorgestrel intrauterine system than the copper IUD. The levonorgestrel intrauterine system has noncontraceptive indications, such as improvement of menorrhagia and dysmenorrhea, which the copper IUD does not.18 However, both IUDs are highly effective and well tolerated. Other possible reasons for this observed ratio is the direct-to-consumer advertising for the levonorgestrel intrauterine system, and “word of mouth” referrals to the project of women who are pleased and satisfied with levonorgestrel intrauterine system use. We also believe there may be a provider bias in favor of the levonorgestrel intrauterine system. Some providers consider the lighter menstrual flow and reduced dysmenorrhea characteristic of the levonorgestrel intrauterine system to be beneficial and subsequently may influence patient choice.
Our finding of similar continuation rates for levonorgestrel intrauterine system and copper IUD are in contrast to some published studies. Godfrey et al performed a multicenter, randomized, controlled, participant-blinded pilot study of 23 adolescents aged 14–18 years assigned to the copper IUD or levonorgestrel intrauterine system.19 In this study, the 6-month continuation rates were 75% for the levonorgestrel intrauterine system and 45% for the copper IUD—this continuation rate for the copper IUD is in marked contrast to ours. When we stratified our findings by age (younger than 21 years compared with 21 years or older), we did find that younger women using the copper IUD were more likely to discontinue compared with older women; however, the younger women's continuation rate of 72% was still substantially higher than in the Godfrey study. The Godfrey study included only adolescents and was limited by its small sample size. Additionally, participants randomized to a contraceptive method may be less likely to be satisfied, thus affecting continuation rates.
Suhonen et al conducted a multicenter, randomized study of 200 women aged 18–25 years assigned to levonorgestrel intrauterine system or OCPs. These investigators noted a 12-month continuation rate of 80% for levonorgestrel intrauterine system, compared with 73% for OCPs.20 Our findings are very similar, although we had a higher continuation rate for the levonorgestrel intrauterine system, and a much lower continuation rates for OCPs. Other studies have also noted high continuation rates for IUDs, in both young women and women of all ages.21
Our continuation rates for all reversible methods of contraception are similar to those quoted by Trussel.21 In our study, women were considered “continuers” as long as they did not stop their method for 4 weeks or longer. This likely overestimated our continuation rate because women who stopped and then restarted a method in the same month would still be considered “continuers” despite potentially being at risk for pregnancy. Lapses in contraceptive use may be caused by switching between methods or temporary discontinuation owing to an expired prescription, difficulty getting to the pharmacy or health care provider, method dissatisfaction, or side effects.16,17 However, even if we overestimated the continuation of methods of non–long-acting reversible contraceptives, we can clearly see that the continuation rates are much higher among the long-acting methods.
Our study found a 12-month continuation rate of 82% for the subdermal implant, which was higher than we expected. The medical literature is limited, but reported 12-month continuation rates ranged from 68% to 78%. A multicenter clinical trial of 330 women using the implant for 2 years noted a 12-month continuation rate of 68%,22 whereas a multicenter observational study of 417 women noted a 78% continuation rate at 12 months.23 Wong and colleagues performed an observational cohort study of 211 subdermal implant users and 228 IUD users, and noted a 6-month continuation rate of 83% for the implant and an 89% continuation rate for the IUD.24 As in our study, these investigators found that IUD users were more satisfied than implant users (74% compared with 58%, P=.002).
The strengths of our study include its prospective design, large sample size, and low rate of loss to follow-up at 12 months. Limitations include a convenience sample, inclusion criterion that specified that participants must be willing to try and initiate a new contraceptive method, and lack of randomization. The convenience sample, inclusion criteria, and regional recruitment may limit the generalizability of our study. Because participants are not randomly assigned a contraceptive method, their baseline expectations of a contraceptive method may be different. We did not believe we could ethically randomize patients to a method of contraception, and randomization may adversely affect continuation, which was one of our primary outcomes. We required that participants try a new contraceptive method so that we could better compare new IUD or implant users with new users of other methods. The question of how to define continuation in this study was a challenge; we had many participants who stopped and restarted their method. Women who stopped their method for 4 weeks or greater were defined as discontinuers; however, women who temporarily discontinued their method within a 4-week period were counted as ”continuers.” The inclusion of these women as continuers may overestimate the continuation rate and bias our results toward the null; however, it does provide a conservative estimate of the effect size.
In conclusion, long-acting reversible contraceptive methods have the highest rates of user satisfaction and continuation of all reversible contraceptive methods. Because they are also the most effective reversible methods of contraception, they should be the methods of choice (first-line option) for women trying to avoid an unintended pregnancy.
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© 2011 by The American College of Obstetricians and Gynecologists.
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