Abstract
OBJECTIVE: To evaluate whether a short course of tamoxifen decreases bothersome bleeding in etonogestrel contraceptive implant users. METHODS: In a 90-day, double-blind randomized control trial, we enrolled etonogestrel implant users with frequent or prolonged bleeding or spotting. A sample size of 40 per group (N=80) was planned to compare 10 mg tamoxifen or placebo twice daily for 7 days after 3 consecutive days of bleeding or spotting no more than once per 30 days (maximum three treatments). Participants then entered a 90-day open-label study where all received tamoxifen if needed every 30 days (maximum three treatments). Participants used text messages to record daily bleeding patterns. Our primary outcome was the total number of consecutive amenorrhea days after the first treatment. Secondary outcomes included time to bleeding or spotting cessation and restart after first treatment, overall bleeding patterns, and satisfaction. RESULTS: From January 2017 to November 2018, 112 women enrolled in the study; 88 (79%) completed 90 days, and 79 (71%) completed 180 days. Participant characteristics did not differ between groups; mean age 24, majority identified as white not Hispanic with at least some college education. After the first treatment, the tamoxifen group reported an average of 9.8 (95% CI 4.6-15.0) more consecutive days of amenorrhea and more total days of no bleeding (amenorrhea or spotting) in the first 90 days (median 73.5 [range 24-89] vs 68 [range 11-81], P=.001). The placebo group showed a similar treatment benefit after first active use of tamoxifen in the open-label phase. At the end of the randomized study (first 90 days), women who received tamoxifen reported higher satisfaction (median 62 mm [range 16-100]) than those treated with placebo (46 mm [range 0-100]; P=.023). CONCLUSION: A short course of tamoxifen reduces problematic bleeding and improves satisfaction in users of etonogestrel implants. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, NCT02903121.