An Observational Study to Learn How Mirena and Other Progestogen Treatments Are Used for Endometrial Protection in Women 40+ With a Uterus in the United States Receiving Estrogen Therapy, and Their Respective Health Outcomes

Study of Real-world Use of Hormonal Levonorgestrel Intra-uterine System for Endometrial Defense With Estrogen Therapy

This is an observational study in which researchers will use claims data already collected from women in the United States who received their usual care. The study will look at women aged 40 years and older who have a uterus and started estrogen therapy.

Estrogen therapy is often used to treat menopause symptoms, such as hot flashes and night sweats, or to help prevent bone loss. Women who take estrogen and still have a uterus usually also need a progestogen to help protect the lining of the uterus. Without this protection, the lining may become too thick. This can lead to endometrial hyperplasia and may increase the risk of endometrial cancer.

This study will look at how Mirena and other progestogen treatments are used in routine medical care to protect the lining of the uterus during estrogen therapy. Mirena is a small device placed in the uterus that releases the hormone levonorgestrel (a synthetic progestogen, similar to progesterone). In the United States, Mirena is approved for birth control and for treatment of heavy menstrual bleeding. Clinicians may also use it for endometrial protection during estrogen therapy. Bayer's Mirena levonorgestrel-containing intrauterine system (LNG-IUS) 52 mg is approved for endometrial protection during hormone therapy in over 100 countries outside of the US.

The main purpose of this study is gain insight into how different progestogen treatments are used in the context of estrogen therapy in women with a uterus, and the health outcomes linked with them. Researchers will describe how often women use estrogen alone, estrogen with Mirena, or estrogen with other progestogen treatments in the past 10 years. Researchers will also look at how often endometrial hyperplasia, endometrial cancer, abnormal or heavy bleeding, and hysterectomy occur in these groups over time.

The data will come from two U.S. health insurance claims databases: Optum Clinformatics Data Mart and MarketScan Commercial Claims and Encounters Database. The study period covers 2014 through 2025, depending on the database. Optum: January 2015-December 2025 and MarketScan: October 2014-September 2025, with patient identification periods of Optum: January 2016-December 2024 and MarketScan: October 2015-September 2024. Researchers will follow each participant's available data for at least 12 months before and at least 12 months after starting estrogen therapy, with follow-up of up to 10 years.

No study treatment will be given as part of this study. Researchers will only review anonymous health insurance claims data that were already collected during routine care.

Inclusion Criteria:

• At least one claim of estrogen therapy (ET) during the patient identification period (Index date: the first claim for ET)
• Age ≥ 40 years at the index date
• Patients with minimum continuous enrollment 12 months prior and 12 months at minimum after index date

Exclusion Criteria:

• Women without a uterus (claims of hysterectomy) in the 12-month baseline period
• Use of any hormonal contraception in the 12-month baseline period
• Claims indicative of atypical endometrial hyperplasia or endometrial cancer or heavy menstrual bleeding (HMB)/abnormal uterine bleeding (AUB)/postmenopausal bleeding (PMB), or any treatment for late state or metastatic endometrial cancer, in the baseline period.
• Claims in the baseline period for any of the treatments of interest
• Claims of chemotherapy/endocrine therapy in the baseline period