A Systematic Review of Outcomes Reported in Gestational Trophoblastic Disease to Inform the Development of a Core Outcome Set: A Protocol

Gestational trophoblastic disease (GTD) is a group of uncommon disorders associated with pregnancy and characterised by abnormal proliferation of trophoblastic tissue. These range from the premalignant partial hydatidiform mole and complete hydatidiform mole to malignant forms known as gestational trophoblastic neoplasia (GTN), including invasive mole, choriocarcinoma, placental site trophoblastic tumor and epithelioid trophoblastic tumor. The incidence of GTD varies globally, with higher rates reported in Africa, Asia and the Middle East. Most forms of GTD are rare diseases and as a result there is little evidence from randomised control trials for optimum treatment and follow-up. This has led to substantial variation in clinical practice across countries. Variability in outcome definitions, data collection practices, and database infrastructure limits comparability between centres, reducing the value of collected data and posing challenges for quality improvement and research. Through the CODING Study, we aim to address this by developing a Core Outcome Set (COS) for GTD. A COS is an agreed standardised set of outcomes that should be measured and reported, as a minimum, in all studies of a specific health condition or intervention. A systematically developed COS is an approach to help standardise outcome measurement, reporting and disease management globally. Our main objective is to assess what outcomes are currently recorded in studies of women with GTD in the literature. A systematic review will be conducted following the PRISA guidelines. An electronic database search will be performed along with a search of professional body and college websites for other relevant sources reporting outcomes in patients diagnosed with GTD. A two-step screening process will be conducted (title & abstract/ full text), data extraction will be performed using a data collection form and recorded in Microsoft excel. Extracted outcomes will be grouped and classified into outcome domains according to the COS 38 Outcome Taxonomy Scale. The findings of this review will generate a comprehensive list of outcomes that will inform subsequent consensus processes to develop a core outcome set for GTD research and clinical practice.