BACKGROUND: The European Active Surveillance Study of LCS12 (EURAS-LCS12) investigates effectiveness and safety of intrauterine devices (IUDs) in routine clinical practice. Here, we aim to characterise the general population of IUD users across Europe recorded in a real-world setting. METHODS: EURAS-LCS12 is a prospective, non-interventional cohort study in ten European countries, that started in 2014. All types of approved IUDs were enrolled: levonorgestrel (LNG)-IUS 8 (LNG release rate ~ 8 µg/day)
LNG-IUS 12 (LNG release rate ~ 12 µg/day
LNG-IUS 20 (LNG release rate ~ 20 µg/day
)
copper IUDs and other hormonal IUDs (OHIUD). A great variety of baseline characteristics and endpoints are assessed in patient-reported questionnaires. The follow-up duration aligns with the intended maximum duration of use of 3 to 5 years, depending on the respective IUD. RESULTS: Currently, 97,187 users are enrolled in the study, of whom the vast majority uses IUDs for contraceptive purposes (96.3%), and roughly two thirds are first-time IUD users (64.1%). Heavy menstrual bleeding (HMB) was reported as the second most common reason for IUD use but with apparent variations between devices and countries. Mean age of LNG-IUD 8 users was about 9 years lower compared with LNG-IUD 20 (26.2 vs. 34.6 years). Greatest differences in the proportion of gravid and parous women were observed between LNG-IUS 8 and OHIUD users (gravid: 38.6% vs. 89.8%
para: 30.6% vs. 88.0%). CONCLUSIONS: With more than 97,000 IUD users, EURAS-LCS12 is one of the largest contemporary studies focusing on IUD usage and provides a substantial source of real-world data. IUD prescription patterns appear in line with assumptions that high-dose LNG-IUDs with longer approved durations of use are predominantly prescribed among older, gravid women, who may have completed their family planning, as opposed to younger nulligravidae. Overall, the study is a great source to depict which IUD type fits women with certain characteristics and needs at a certain time of life. TRIAL REGISTRATION: NCT02146950.