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The COMET Initiative: Developing core outcome measures

Posted on 22nd December 2014 by

Tutorials and Fundamentals
The COMET initiative

The COMET or Core Outcome Measures in Effectiveness Trials Initiative: Developing and applying an agreed-upon set of outcome measures in medical research.


Oh so you might have heard about the recent Philae landing on Comet 67P/Churyumov-Gerasimenko, well this blog has absolutely nothing to do with that kind of comet. This blog is about Core Outcome Measures in Effectiveness Trails, or COMET for short.

Ok, so what is COMET?

The COMET Initiative was started in 2010 by researchers in Liverpool who are trying to improve quality and reduce waste in research. They do this by helping researchers come up with agreed-upon tests or ‘core outcomes’ for research studies. This means that when studies are done, the same tool that measures any change due to a medical treatment is also used in other studies about the same topic.

The COMET Initiative also provides a central place where researchers and patients can find out what core outcome sets researchers have already come up with for other studies.

So why do we need this?

Look, here is how the COMET Initiative website describes the issue:
Imagine two studies about how to treat migraine.

  • Study A – researchers measure days off sick as an outcome
  • Study B – researchers measure symptoms of pain as an outcome

When the two studies are finished, we can’t really compare or combine their results in a meaningful way because they have used different outcomes, in this case, sick days off work or pain symptoms. We also don’t know which outcome is more important to people who have migraines. Do you see the problem?

Now all of this is not saying that other outcomes shouldn’t be used, but researchers could at least agree upon a carefully selected outcome(s) as minimum or “core outcomes”.  In medical research there are literally hundreds of different outcome measures. Having an agreed upon core set of outcome measures would help researchers combine and compare the results of the different studies. This would increase efficiency in research by helping researchers combine the data from the different studies into more meaningful meta-analysis.

There is a big push right now to increase the quality and reduce waste in research. Part of that effort is in answering these two questions:

  1. What matters most to patients?
  2. Which outcome measure(s) can we agree to prioritize and use as a minimum for research on a particular topic?

Alright, so how are outcomes agreed upon?

Core outcome measures are agreed upon by using a combination of surveys, expert opinions, and patient feedback. Most importantly, patients are now more involved and explain what is meaningful to them, based on their first-hand experiences of living with a condition. So, basically it’s by consensus.

Where can I learn more?

Here is a link to the COMET website. There are several other organizations that have also been working on a solution to finding what matters most to patients. Richard Lehman blogged about a recent JAMA Viewpoint article  which described an organization called the Patient-Centred Outcomes Research Institute (PCORI). This group helps fund research that finds and clarifies patient-centred outcomes.

Similarly, there is The James Lind Alliance  which brings patients, caregivers, and clinicians together to identify the ‘top 10 research priorities’. They also help researchers learn about the effects of treatments as well as what matters most to clinicians and patients.

Conclusions & comment

The COMET Initiative, PCORI and the James Lind Alliance are doing some amazing things. They have already helped improve the quality of research by just helping us all ask the right questions.  As students, we can get our own research moving in the right direction by learning from what has already been identified as important to patients, and using outcome measures that others have agreed are most useful.

Still, finding out what is meaningful to patients and getting researchers to agree on outcomes is not without its own challenges. As far as I see it, the COMET Initiative is a step in the right direction.

I would love to hear what you think. Do you think it’s realistic to insist that a researcher use a particular outcome measure? If researchers do identify what outcomes are important to most patients, can we really generalize that these outcome measures are truly the most meaningful to each individual patient we treat?


For more information about the Core Outcome Measures in Effectiveness Trials’ Initiative click here http://www.comet-initiative.org/

For more information about The James Lind Alliance click here http://www.jla.nihr.ac.uk/about-the-james-lind-alliance/

For more information about Patient Centred Outcome Measures click this link. http://www.pcori.org/

Gargon, E., Williamson, P. R., Altman, D. G., Blazeby, J. M., & Clarke, M. (2014). The COMET Initiative database: progress and activities from 2011 to 2013. Trials, 15(1), 279. doi:10.1186/1745-6215-15-279

Frank L, Basch E, Selby JV, & For the Patient-Centered Outcomes Research Institute. (2014). The pcori perspective on patient-centered outcomes research. JAMA, 312(15), 1513–1514. doi:10.1001/jama.2014.11100

BMJ Blogs: The BMJ, Richard Lehman’s journal review—(20 October 2014).  Retrieved from http://blogs.bmj.com/bmj/2014/10/20/richard-lehmans-journal-review-20-october-2014/

Williamson, P., Altman, D., Blazeby, J., Clarke, M., & Gargon, E. (2012). Driving up the quality and relevance of research through the use of agreed core outcomes. Journal of Health Services Research & Policy, 17(1), 1–2. doi:10.1258/jhsrp.2011.011131


Danny Minkow

Danny Minkow has a History degree from the University of Florida. He then served with the US Air Force for 7 years and is an Iraq War veteran. He is currently pursuing a Master's of Science in Occupational Therapy at Brenau University near Atlanta, Georgia. Danny has great interest in The Cochrane Collaboration and how medical evidence is used and communicated. Particularly the differences between how the UK and US view and apply the best available evidence. He is currently working on a group thesis for stroke rehabilitation. View more posts from Danny

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