Core Outcome Measures in Effectiveness Trials

Developing a Core Outcome Set in Endometriosis

General Information

Endometriosis affects 1 in 10 women and impairs health related quality of life, especially in the domains of pain, psychological and social functioning. Trials and systematic reviews evaluating potential interventions have reported many different outcomes resulting in significant outcome reporting bias and an inability to synthesize results across studies. The development and use of a core outcome set would help to address these issues.

Aims and objectives
The International Collaboration to Harmonise Outcomes in Endometriosis (iHOME) aims to produce, disseminate, and implement a core outcome set for endometriosis.

James Duffy – Balliol College, Oxford University
Martin Hirsch - Queen Mary, University of London
Colin Davis – Barts Health NHS trust
Cindy Farquhar – Coordinating Editor, Cochrane Menstrual Disorders and Subfertility Group

Further Study Information

Current Stage:
October 2015 - October 2017
Funding source(s):

Health Area

Disease Category

Disease Name

Target Population

Age Range
13 - 51


Nature / type of Intervention


Delphi process
Focus group(s)
Literature review

Stage 1: Identify Outcomes
Stage 2: Determining Outcomes
Stage 3: Implementation and dissemination

Stage 1: Identifying Potential Outcomes
Stage 1 (A): Systematic review (month 1-9): A comprehensive literature review will identify randomised controlled trials evaluating interventions for endometriosis. Reported outcomes and outcome measures will be catalogued.
Stage 1 (B): Focus groups (month 10-13): Patients require specific attention when creating core outcome sets as they often identify outcomes not considered by other stakeholders or within the literature. Patients will be recruited to take part in semi- structured focus groups. The focus group methodology will be developed in consultation with patient representatives and guided by the literature review. Thematic content analysis will identify potential core outcomes.
Stage 1 (C) Outcome inventory (month 14-15): A comprehensive inventory of outcomes identified by the systematic review and focus groups will be developed. The outcome inventory will be entered into the Delphi methodology (Stage 2).
Stage 2: Determining core outcomes (Delphi methodology)
Delphi methodology (month 16-23): All stakeholders will be invited to participate in a process that assesses the extent of agreement (consensus measurement) and then resolves disagreement (consensus development). Repeated reflection and scoring increases the likelihood of whole and stakeholder group convergence towards consensus “core” outcomes.

Stage 3: Implementation and Dissemination
A draft document summarising the background information, methodology, and results will be circulated and presented at various stakeholder events. Stakeholder feedback will be collated, reviewed, and incorporated into the finalised core outcome set prior to dissemination and implementation.

Stakeholders Involved

Clinical experts
Consumers (patients)
Pharmaceutical industry representatives

Study Type

COS for clinical trials or clinical research

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