By Jeffrey T. Jensen, MD, MPH
Leon Speroff Professor and Vice Chair for Research, Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland
Dr. Jensen reports that he is a consultant for and receives grant/research support from Bayer, Abbvie, ContraMed, and Merck; receives grant/research support from Medicines 360, Agile, and Teva; and is a consultant for MicroChips and Evofem.
SYNOPSIS: A new analysis from the National Survey of Family Growth demonstrates a decrease from 12% in 2002 to 10% in 2006-2010 in the overall rate of failure among women using reversible methods of contraception.
SOURCE: Sundaram A, Vaughan B, Kost K, et al. Contraceptive failure in the United States: Estimates from the 2006-2010 National Survey of Family Growth. Perspect Sex Reprod Health 2017;49:7-16. doi: 10.1363/psrh.12017. [Epub ahead of print].
Over the past several years, increased attention to real-world failure rates associated with short-acting reversible hormonal contraceptive (SARC) methods, such as the contraceptive pill, has led to broad recommendations from the family planning community to shift the emphasis on counseling to long-acting reversible contraception (LARC) methods with low rates of typical use failure. Sundaram et al used data on contraceptive failure available from the 2006-2010 sample of the National Survey of Family Growth (NSFG), and compared these to estimates from earlier NSFG surveys conducted in 1995 and 2002. The authors used data from the Guttmacher Institute’s 2008 Abortion Patient Survey to adjust for under-reporting of abortion in calculating the risk of failure.
In the 2006-2010 sample, users of LARC methods (intrauterine devices and the implant) had the lowest failure rates of all methods (< 1%), while users of condoms (13%) and withdrawal (20%) reported the highest probabilities of failure. Important trends became apparent when comparing these results to the earlier samples. First, the overall rate of contraceptive failure for all reversible methods declined from 15% in 1995 to 10% in 2006-2010 (-4.6%; P < .001). In particular, the failure rate during this interval declined significantly among condom (-5%; P < .01) and withdrawal (-8.5%; P < .05) users, with a trend toward improvement among users of the pill (-1.6%; P > .05) and injectables (-1.4%; P > .05; 95% confidence intervals not reported). With the exception of withdrawal, the bulk of these improvements in effectiveness occurred between the 2002 and 2006-2010 samples. The failure rate for all reversible methods combined declined from 12% in 2002 to 10% in 2006-2010.
The authors further evaluated the user characteristics associated with contraceptive failure in the 2006-2010 sample. They found that for most methods, about one-third of failures occurred during the first three months of use and almost two-thirds occurred within six months. LARC methods provide the exception to this rule, with failure distributed evenly throughout the first year of use. Although women with and without children experienced similar probabilities of contraceptive failure in 1995, the group of never-pregnant women experienced an 8% drop by 2002 (from 14% to 6%) and further reduction in 2006-2010 (cumulative 9% decrease). This 5% probability of failure in women without children is nearly three-fold lower than the 14% seen in women with one or more children in 2006-2010 (P < .001). Poverty, black race, and Hispanic ethnicity all were associated with an increased risk of contraceptive failure, while being married decreased this risk. The risk of contraception failure decreased among all age groups, with the greatest reduction seen in women 20-24 years of age (from 17% to 11%, a 6% reduction).
COMMENTARY
In the March issue of OB/GYN Clinical Alert, I discussed proposed policy changes that threaten to undermine advances made in reducing the burden of unintended pregnancy. Good policy should be informed by evidence. The paper by Sundaram et al used longitudinal data available from the NSFG, a nationally representative sample of reproductive and sexual behavior in the United States. The 1995 and 2002 samples represent data collections over a single year. Beginning in 2006, the NSFG moved to a continuously sampling format. In this paper, the authors used data from the 2006-2010 sample. The most recently published data come from the 2011-2013 collection.1 Although causality cannot be inferred from the descriptive results presented in this paper, the broad improvement in the overall effectiveness of reversible contraceptive methods has significance for our clinical and political decision-making.
First, declines in the failure rates of virtually all reversible methods occurred broadly within every demographic group, and reverses a long pattern of minimal improvement. A likely explanation for this is the shift to LARC methods. Notably, the use of LARC methods increased from 1.5% to 3.8% between 2002 and 2006-2010. A small decrease in the number of users of condoms and the pill suggest that women shifting from these methods contributed to most of the LARC increase. All of these trends continued in the 2011-2013 sample, with LARC use reported at 7.2%, and a further decrease in the number of women using the pill or condoms.1 Policies such as the Affordable Care Act have directly contributed to increased LARC uptake.2
Keep in mind that the reduction of risk of failure does not mean that all methods are equally effective. In fact, the probability of condom failure remains above 12%, compared with 7% for oral contraceptives or < 1% for LARC methods. This strongly suggests that the technical problems associated with condom use have not disappeared. What these data do suggest is that dissatisfied (unreliable) users of the pill and condoms have moved on to accept LARC methods, leaving the most reliable and consistent users behind. In other words, we have shifted the overall characteristics of the population of pill and condom users closer to “perfect” use. Since outcomes are best for any method with correct and consistent use, we see a reduction in the overall proportion using these methods experiencing failure. Since the LARC train continues to gather steam, we can expect to see a further decrease in the proportion of failure for all methods. However, this does not mean that all potential users will experience perfect use failure rates.
Clinicians should consider these caveats. Effective contraceptive counseling must emphasize the inherent superiority of LARC methods. All things being equal, fewer than 1% of users of these methods will experience pregnancy, and achieving this benefit requires no additional action by the woman. That said, women who would prefer not to use a LARC method should receive detailed counseling on strategies to improve the use of a SARC. For women taking a daily oral vitamin, thyroid, or antidepressant medication, the addition of an oral birth control pill requires little effort. Women highly motivated to use condoms also should receive counseling for emergency contraception. In other words, encourage correct and consistent use of the most acceptable method to the woman. The goal is perfect use effectiveness.
The results from CHOICE and other studies suggest that LARC methods make achieving perfect use easier for many women. We need to continue advocating for health policies that provide cost-free access to the full range of LARC and SARC methods to all women.
REFERENCES
- Daniels K, Daugherty J, Jones J, Mosher W. Current Contraceptive Use and Variation by Selected Characteristics Among Women Aged 15-44: United States, 2011-2013. Natl Health Stat Report 2015;86:1-14.
- Finer LB, Zolna MR. Declines in unintended pregnancy in the United States, 2008-2011. N Engl J Med 2016;374:843-852.
A new analysis from the National Survey of Family Growth demonstrates a decrease from 12% in 2002 to 10% in 2006-2010 in the overall rate of failure among women using reversible methods of contraception.
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