Etonogestrel Implant as Backup in Patients Primarily Using a Combined Oral Contraceptive Pill: A Multicenter Trial [ID 3339]

INTRODUCTION: A prior single-institution pilot study demonstrated high etonogestrel implant continuation and low adverse event rates through 6 months when the implant was placed for concurrent use with a combined oral contraceptive (COC). We primarily aimed to evaluate implant and COC continuation over 12 months. METHODS: We enrolled new and current COC users amenable to etonogestrel implant placement as backup contraception into an IRB-approved, multicenter study. Participants attended in-person or remote visits at 1, 3, 6, 9, and 12 months after implant placement, regardless of implant continuation. We assessed implant and COC continuation at 12 months and reasons for implant discontinuation. RESULTS: From August 2020 to March 2023, we enrolled 120 participants, including 31 (26%) new-start and 89 (74%) current COC users. Ninety-six (80%) participants completed the 12-month exit visit. Most study discontinuations occurred for lost-to-follow-up (LTFU) (18 [15%]) or consent withdrawal (4 [3%]). At 12 months, 46 (48%) participants continued concurrent implant and COC use, 40 (42%) continued implant use alone, 5 (5%) continued COC alone, and 5 (5%) had discontinued both methods. Implant continuation occurred in 23 (88%) new-start and 63 (90%) current COC users. Thirteen participants (including 3 subsequently LTFU) had implant removal for bleeding complaints (n=5), other side effects (n=7), and wanting to use one hormonal method (n=1). CONCLUSIONS/IMPLICATIONS: Implant continuation rates through 12 months are very high when the implant is initially placed as a backup method for COCs. Nearly half of the participants who intended implant use as backup changed to using it as their primary contraceptive.