The COMET initiative

Comet inititative launch speakersSystematic reviews of randomised trials are hampered by inconsistency in the patient outcomes assessed across the different studies. Many meta-analyses have to leave out key studies because the relevant outcomes were not reported. Much could be gained if each medical condition had an agreed minimum set of core outcomes that were measured and reported in all clinical trials. Systematic reviews and cross-study comparisons would be easier, the design of new trials would be simplified, and there would be reduced risk of bias from selective reporting of outcomes (Kirkham 2010). Efforts are underway to achieve this.

In January this year, the COMET initiative was launched at a meeting in Liverpool to discuss core outcome sets for the effectiveness of clinical trials, bringing together more than 100 participants. Journal editors, regulators, consumers, policy makers, trial funders, trialists and systematic reviewers heard from several people working in the area and we’ve put their talks on the internet ( Among the presentations, Peter Tugwell described the achievements of the OMERACT group in developing core outcomes for several diseases in rheumatology. Heather Bagley, a parent attending the meeting, writes

“I was very excited to have attended the core outcomes in clinical trials meeting as it feels like a hugely important and critical way forward in conducting clinical trials.  As a parent you trawl through the literature on your child’s condition and when you find relevant studies to your child’s condition there is no way of comparing the information you find as many studies use such different outcome measurement tools. I am confused as a parent!  Goodness knows how practitioners feel when they have to make clinical decisions based on incomparable data. I was overwhelmed by the positivity in the core outcome meeting and felt relieved as a consumer that such an essential issue is finally being addressed.  The ground-breaking work of the international Rheumatology team was hugely inspiring and gave great direction to the meeting.  The panel discussion was equally enthusiastic and refreshingly light-hearted.  The meeting made the matter of addressing core outcomes seem realistically challenging but do-able.  As a consumer I felt I was at the birth of something pretty awe-inspiring. Glad to have been there.”

The COMET (Core Outcome Measures in Effectiveness Trials) initiative is an international network bringing together individuals and organisations interested in the development, application and promotion of core outcome sets. We aim to collate relevant resources, both applied and methodological, facilitate exchange of ideas and information, and foster methodological research.

Further information about COMET can be found at along with podcasts from most of the speakers at the Liverpool meeting (photo). We would be delighted to hear from anyone interested in this topic.

We are grateful for the funding provided for this meeting by the MRC North West Hub for Trials Methodology Research.

Paula Williamson, Jane Blazeby, Doug Altman and Mike Clarke
Photograph – COMET Initiative Launch speakers
l-r: Professor Jane Blazeby, Professor Doug Altman, Professor Mike Clarke, Dr Angus McNair, Professor Paula Williamson, Professor Peter Tugwell, Dr Ian Sinha.

Kirkham JJ, Dwan KM, Altman DG, Gamble C, Dodd S, Smyth R, Williamson PR
(2010) The impact of outcome reporting bias in randomised controlled trials on a cohort of
systematic reviews. BMJ 340: c365, doi: 10.1136/bmj.c365