Core Outcome Measures in Effectiveness Trials

Development of a core outcome set to assess the adverse outcomes after treatment for haemorrhoids in clinical trials

General Information

This study will define a standard set of measures (called outcomes) that can be used to assess how effective and safe treatment for haemorrhoids is. This set of measures is called a core outcome set (COS).

At the moment studies investigating surgery for haemorrhoids do not use a standard set of measure to assess treatment of haemorrhoids. This can make it difficult to compare results of different studies and formulating best treatment options. Some studies record a large number of outcome measurements and only publish some of the recorded outcomes. In this way the authors will bias outcome regarding particular treatments.

A solution of this problem is developing a core outcome set (COS). This is the minimum set of outcomes that should be studied and reported in any trial regarding haemorrhoidal treatment. Using this set of outcomes in every study would make it much easier comparing different studies.

The first step in developing is a list of all outcomes that have been measured and reported regarding treatment of hemorrhoids by reviewing the literature in a standardised way. Besides healthcare outcome parameters also patient outcome variables will be included in this overview.

The next step will be the Delphi process: This is a standardised scoring process leading to a reduced outcome list. Finally it will result in a short list, which will be the core outcome set.

R.R. van Tol PhD (principal investigator)
Dr S.O. Breukink (supervisor)
Prof. L.P.S. Stassen

Maastricht University Medical Centre

Further Study Information

Current Stage:
December 2014 - June 2016
Funding source(s):

Health Area

Disease Category

Disease Name

Target Population

Age Range
18 - 100


Nature / type of Intervention


Consensus meeting
Delphi process
Systematic review

This study will follow a validated multistage approach recommended by the OMERACT and COMET initiatives ( and will consist of three phases.

Phase 1 – Systematic reviews
Two systematic reviews will be performed, one will identify all possible clinical outcomes (Review 1) reported in randomised controlled trials, longitudinal studies (cohort studies, case-control studies and prospective case series), cross-sectional studies and retrospective case series (Excluding case reports) of patients who have undergone surgery for haemorrhoids. The second review (Review 2) will identify all possible patient reported outcomes in each of the included study types. This review strategy will identify all potential outcomes (clinical and patient reported).

Phase 2 Questionnaire survey of key stakeholders
Key stakeholders (Patients and healthcare professionals) will be surveyed using a Delphi methodology. The comprehensive lists of outcomes and disclosure information will be refined into core sets in two concurrent Delphi processes. Each Delphi process will consist of two rounds of questionnaires completed by patients, surgeons and relevant healthcare professionals. The lists of outcomes and disclosure information will be formatted initially into questions or ‘items’ with a Likert response designed to allow participants to rate each item’s value for inclusion in the final core outcome/disclosure sets.

Phase 3 Consensus meetings of key stakeholders
A consensus meeting will be held with key stakeholders to validate the final core disclosure set and to discuss questions about which there is ‘disagreement’ in Delphi round 2.

Sample size
The numbers of participants required for a Delphi process is currently unclear however it is planned that 20 patients and 15 healthcare professionals will be recruited.

Stakeholders Involved

Clinical experts
Consumers (patients)

Study Type

COS for clinical trials or clinical research

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