Predicting long-term bleeding patterns after etonogestrel implant insertion
Mansour D, Fraser IS, Edelman A, et al. Can initial vaginal bleeding patterns in etonogestrel implant users predict subsequent bleeding in the first two years of use? Contraception. 2019. doi: 10.1016/j.contraception.2019.05.017.
Data from 2014 indicate that the etonogestrel implant was used by nearly 1 million women in the United States and by 3% of women using contraception.1 The primary reason women discontinue implant use is because of changes in bleeding patterns. Given the high prevalence of bleeding concerns with the etonogestrel implant, we need more data to help counsel our patients on how they can expect their bleeding to change with implant use.
Etonogestral implant and bleeding pattern trends
Mansour and colleagues completed a secondary analysis of 12 phase 3 studies to evaluate the correlation between bleeding patterns early after placement of the etonogestrel implant (days 29-118) compared with bleeding patterns through 90-day intervals during the rest of the first year of use. To account for differences in timing of etonogestrel implant placement relative to the menstrual cycle and discontinuation of other methods like oral contraceptives, bleeding outcomes on days 0-28 were excluded. They also sought to investigate the correlation between bleeding patterns in year 1 compared with those in year 2.
Overall, these studies included 923 individuals across 11 countries; however, for the current analysis, the researchers excluded women from Asian countries who comprised more than 28% of the study population. These women report significantly fewer bleeding/spotting days with the etonogestrel implant and have a lower average body weight compared with European and American women.12
A prior analysis of the same data set looked at the number of bleeding/spotting days in groups of users rather than trends in individual patients, and, as mentioned, it also included Asian women, which diluted the overall number of bleeding days.12 In this new analysis, Mansour and colleagues used the Belsey criteria to analyze individual bleeding patterns as favorable (amenorrhea, infrequent bleeding, normal bleeding) or unfavorable (prolonged and/or frequent bleeding) from a patient perspective. In this way, we can understand trends in bleeding patterns for each patient over time, rather than seeing a static (cross-sectional) report of bleeding patterns at one point in time. Data were analyzed from 537 women in year 1 and 428 women in year 2. During the first 90-day reference period (days 29-118 after implant insertion), 61% of women reported favorable bleeding, and 39% reported unfavorable bleeding.
Favorable bleeding correlates with favorable patterns later
A favorable bleeding pattern in this first reference period correlated with favorable bleeding patterns through year 1, with 85%, 80%, and 80% of these women having a favorable pattern in reference periods 2, 3, and 4, respectively. Overall, 61% of women with a favorable pattern in reference period 1 had favorable bleeding throughout the entire first year of use. Only 3.7% of women with favorable bleeding in the first reference period discontinued the implant for bleeding in year 1. Further, women with favorable bleeding at year 1 commonly continued to have favorable bleeding in year 2, with a low discontinuation rate (2.5%) in year 2.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Individual patients who have a favorable bleeding pattern initially with etonogestrel implant placement are highly likely to continue having favorable bleeding at year 1 and year 2. Notably, of women with a favorable bleeding pattern in any 90-day reference period, about 80% will continue to have a favorable bleeding pattern in the next reference period. These women can be counseled that, even if they have a 90-day period with unfavorable bleeding, about two-thirds will have a favorable pattern in the next reference period. For those with initial unfavorable patterns, about one-third to one-half change to a favorable pattern in subsequent 90-day reference periods. For women who require intervention for unfavorable bleeding but wish to keep their etonogestrel implant, prior data support use of combined oral contraceptive pills, although bleeding resolution seems to be temporary, with 86% of women having bleeding recurrence within 10 days after treatment.13
Individual patients who have a favorable bleeding pattern initially with etonogestrel implant placement are highly likely to continue having favorable bleeding at year 1 and year 2. Notably, of women with a favorable bleeding pattern in any 90-day reference period, about 80% will continue to have a favorable bleeding pattern in the next reference period. These women can be counseled that, even if they have a 90-day period with unfavorable bleeding, about two-thirds will have a favorable pattern in the next reference period. For those with initial unfavorable patterns, about one-third to one-half change to a favorable pattern in subsequent 90-day reference periods. For women who require intervention for unfavorable bleeding but wish to keep their etonogestrel implant, prior data support use of combined oral contraceptive pills, although bleeding resolution seems to be temporary, with 86% of women having bleeding recurrence within 10 days after treatment.13
Initial unfavorable bleeding portends less favorable patterns later
Women who had an unfavorable bleeding pattern initially, however, had a less predictable course over the first year. For those with an initial unfavorable pattern, only 37%, 47%, and 51% reported a favorable pattern in reference periods 2, 3, and 4. Despite these relatively low rates of favorable bleeding, only 13% of the women with an initial unfavorable bleeding pattern discontinued implant use for a bleeding complaint by the end of year 1; this rate was significantly higher than that for women with a favorable initial bleeding pattern (P<.0001). The discontinuation rate for bleeding complaints also remained higher in year 2, at 16.5%.
Limitations and strengths to consider
Although the etonogestrel implant is FDA-approved for 3 years of use, the bleeding data from the combined trials included information for only up to 2 years after placement. The studies included also did not uniformly assess BMI, which makes it difficult to find correlations between bleeding patterns and BMI. Importantly, the studies did not include women who were more than 30% above their ideal body weight, so these assessments do not apply to obese users.12 Exclusion of women from Southeast Asia in this analysis makes this study's findings more generalizable to populations in the United States and Europe.
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