Mifepristone as a non-emergency contraceptive among women of reproductive age: a protocol for systematic review and meta-analysis

Background: Mifepristone is a selective progesterone receptor modulator with decades of data demonstrating its potential as a highly effective emergency as well as non-emergency contraceptive. Despite considerable evidence pointing to the potential effectiveness of mifepristone as a non-emergency contraceptive, no systematic review has been conducted to synthesise the available evidence. This systematic review aims to synthesise the current evidence on the use of mifepristone as a non-emergency contraceptive to prevent pregnancy among cisgender girls and women of reproductive age.

Methods: We developed an electronic search strategy in collaboration with the research librarian. We will search five databases (Ovid Medline, CINAHL, EMBASE, Cochrane-Central Trials and Global Health) from inception and identify additional studies using several grey literature search strategies. All databases will be searched from inception, and we planned to complete the search by 30 June 2024. An Ovid Medline search strategy conducted on 24 May 2024 is provided as an example. We will include all studies that involve cisgender girls and/or women of reproductive age (defined as 54 years or younger), which assessed mifepristone as a non-emergency contraceptive to prevent pregnancy. The primary outcome is contraceptive effectiveness. Two independent reviewers will screen studies for eligibility through title, abstract, and full-text review. We will extract data with Covidence software using a Cochrane Effective Practice and Organisation of Care (EPOC)-adapted data-extraction tool and will assess risk of bias using the EPOC risk of bias tool and the Newcastle-Ottawa Scale. If sufficient data are available, we will conduct a meta-analysis using fixed and/or random effect models. However, if we are unable to conduct a meta-analysis, we will present the results narratively using the synthesis without meta-analysis guidelines and the EPOC table recommended for presenting findings without meta-analysis. Grades of Recommendation, Assessment, Development and Evaluation will be used to assess the quality of the evidence. We will report this review according to Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols guidelines.

Ethics and dissemination: This review is focused on secondary data and does not require any ethical approval. We aim to publish the review in a peer-reviewed scientific journal to promote knowledge transfer and present results using other knowledge translation mediums.

Prospero registration number: CRD42024554720.