Real-world outcomes of the levonorgestrel-releasing intrauterine system for heavy menstrual bleeding or dysmenorrhea in Japanese patients: A prospective observational study (J-MIRAI).

OBJECTIVES: We collected real-world data on the safety and clinical outcomes of the levonorgestrel-releasing intrauterine system (LNG-IUS) for heavy menstrual bleeding and dysmenorrhea. STUDY DESIGN: This was a prospective, multicenter, single-cohort, open-label, post-authorization 12-month follow-up study of Japanese patients initiating the LNG-IUS for heavy menstrual bleeding and/or dysmenorrhea. The primary endpoint was the safety profile based on adverse events and adverse drug reactions (ADRs), including expulsions and abnormal bleeding, within 12 months of LNG-IUS insertion. Secondary endpoints included changes from baseline in menstrual blood loss based on bleeding days and dysmenorrhea graded on a visual analog scale (VAS). RESULTS: Of the 595 patients included, many had underlying conditions such as adenomyosis (39.5%), uterine leiomyoma (30.8%), or endometriosis (12.9%). The incidences of ADRs and serious ADRs were 59.7% and 0.3%, respectively. Frequently reported ADRs were metrorrhagia (48.9%), procedural pain (14.1%), and ovarian cyst (6.2%). The cumulative incidence of expulsions at 12 months was 8.7%. Risk factors for expulsion were obesity (body mass index ≥25 kg/m2), adenomyosis, and uterine cavity length ≥8 cm. The median [interquartile range] VAS score for dysmenorrhea improved from 46.5 [13.0-68.0] at insertion to 1.0 [0.0-13.0] at 12 months, and improvements were also observed in chronic pelvic pain and painful defecation. CONCLUSIONS: The LNG-IUS safely and effectively reduced dysmenorrhea, chronic pelvic pain, and painful defecation. Risk factors for expulsion suggest that patients with underlying organic disease should be monitored carefully when using the LNG-IUS. IMPLICATIONS: The LNG-IUS is an effective treatment for secondary dysmenorrhea with organic disease, and for the reduction of chronic pelvic pain; however, physicians should be aware of the increased risk of expulsion in patients with organic conditions.