A protocol for developing, disseminating, and implementing a core outcome set for adenomyosis research.

Background: Adenomyosis is a common benign gynaecological condition that has been associated with heavy and/or painful periods, subfertility and poor obstetric outcomes including miscarriage and preterm delivery. Studies evaluating treatments for adenomyosis have reported a wide range of outcomes and outcome measures. This variation in outcomes and outcome measures prevents effective data synthesis, thereby hampering the ability of meta-analyses to draw useful conclusions and inform clinical practice.

Objectives: Our aim is to develop a minimum set of outcomes to be reported in all future studies that investigate any uterus-sparing intervention for treating uterine adenomyosis. Wide adoption of 'core outcomes' into research on adenomyosis would reduce the heterogeneity of studies and make data synthesis easier. This will ultimately lead to comparable, prioritised, and patient-centred conclusions from meta-analyses and guidelines.

Materials And Methods: Outcomes identified from a systematic review of the literature will form a long list, agreed by an international steering group representing key stakeholders, including healthcare professionals, researchers, and public research partners. Through a modified Delphi process, key stakeholders will score outcomes from the agreed long list on a nine-point Likert scale that ranges from 1 (not important) to 9 (critical). Following the Delphi process, the refined outcome set will be finalised by the steering group. Finally, the steering group will develop recommendations for high-quality measures for each outcome. The study was prospectively registered with Core Outcome Measures in Effectiveness Trials Initiative; number 1649.

Conclusion: The implementation of the core outcome set for adenomyosis in future trials will enhance the availability of comparable data to facilitate more patient-centred evidence-based care.

What Is New?: The core outcome set will facilitate the generation of clinically important and patient centred outcomes for studies evaluating treatments for adenomyosis.