Three-year efficacy, safety, and tolerability outcomes from a phase 3 study of a low-dose copper intrauterine device.

Abstract

Objectives: To assess 3-year efficacy, safety, and tolerability of the Cu 175mm² copper intrauterine device (IUD).

Study design: This single-arm trial recruited participants at risk of pregnancy aged 17-45 years at 42 U.S. centers to receive a Cu 175mm² IUD with a flexible nitinol frame. We assessed efficacy in participants ≤35 years old at enrollment and assessed all other outcomes in the entire population. We calculated the Pearl Index (pregnancies/100 person-years) through 3 years as the primary efficacy outcome. Secondary outcomes included pregnancy percentages by life-table analysis, placement success, safety (adverse events), and tolerability.

Results: Of 1620 enrollees, 1601 (98.8%) had successful IUD placement, with 1397 ≤35 years at enrollment. We observed a 1-year Pearl Index of 0.94 (95%CI 0.43-1.78) and 1-year and cumulative 3-year life-table pregnancy rates of 1.26% (95%CI 0.57%-1.95%) and 2.47% (95%CI 1.34%-3.60%), respectively. The most common adverse events included bleeding and pain. Over 3 years, 15.4% of participants discontinued due to bleeding or pain. Device expulsions occurred in 36 (2.2%) and 63 (3.9%) participants over 1 and 3 years, respectively. Eight related serious adverse events occurred, including five ectopic pregnancies and one each of uterine perforation, anemia, and uterine hemorrhage. One- and three-year continuation rates were 78.9% and 49.6%, respectively.

Conclusion: These data support efficacy, safety, and tolerability of the Cu 175mm² IUD during the first 3 years of use.

Clinical trial: NCT03633799.