When 26 patient organizations and advocates sign a letter urging the government to do something it’s time to sit up and take note.  Alot of good, smart and effective people support the move to press the federal government to use the Canadian Consensus Criteria (CCC)  in all their programs. The patient response on Phoenix Rising , not surprisingly, has been enthusiastic.


Advocates and organizations have banded together to prod the federal government to adopt the Canadian Consensus definition

Feather Ruffling Time

But is it the right thing to do? With all due respect to all the work and energy that’s gone into producing the letter and now the petition, I propose not. I think the effort,while obviously well intentioned could have negative consequences.

I believe focusing on post-exertional malaise is the ticket out for ME/CFS, and given the CCC’s emphasis on that I’ve always assumed the CCC, or a definition close to it, would play a major role in getting this disorder understood and treated. The CCC had  everything the Fukuda definition didn’t; it was homegrown in the ME/CFS community, it got buy-in from major ME/CFS figures, it focused on the core symptoms…it seemed perfect.

One question -‘ Where was Lenny Jason” – always nagged, though.   Our foremost expert on definitions and the author of over 18 studies on ME/CFS definition and symptom characterization, Lenny Jason was not anywhere to be found. Surely he, of all people had been asked but he didn’t participate.  Two studies in the last year suggested a reason why.

The studies suggested the Canadian Consensus Criteria got it almost all right; it was designed by physicians with great experience with this disorder, it highlighted core aspects of the illness (PEM and cognitive issues), and did away with the emphasis on fatigue but it may has one major flaw that could be devastating. That flaw could inadvertently assist ME/CFS in being viewed  as a  psychological disorder.

Two studies by the DePaul Jason group suggest both the CCC and ICC  may select for ME/CFS patients with very, very high rates of mood disorders.  That the definitions select for more disabled patients suggests some increase in the rate of psychiatric disorders would be expected but  not to the rate found in Jason’s studies. A 2013 study found that over 60% of the  patients selected by the International Consensus Criteria had a psychiatric disorder. A 2012 study found that 58% of CCC selected patients had  a mood disorder. With the  average rate of mood disorders in cardiac disease ranging from 17-27%; in cancer from 22-29%, in diabetes from 9-26%, that percentage of mood disorder appears to be unmatched in the annals of chronic non-mental illnesses.

The studies had their flaws and need to be redone; they may have greatly overestimated the rates of mood disorder in CCC/ICC selected patients.  It’s also possible that ME/CFS is associated with  high enough rates of mood disorders for it to be classified as a psychiatric disorder.  The most likely explanation, however, is that the way the ICC and CCC are formed pre-selects for groups of patients with high rates of mood disorders.  In fact the history of ME/CFS bears this out.

Deja Vu All Over Again?

The (chronic fatigue syndrome) patients with the highest numbers of medically unexplained physical symptoms had extraordinarily high rates of current and lifetime psychiatric disorders. Katon and Russo, 1992

Defining ME/CFS

The Jason groups study suggests defining chronic fatigue syndrome is more complex than expected

The first definition for chronic fatigue syndrome, the Holmes definition, required 8 symptoms but when a study by Katon and Russo came out suggesting that more symptoms meant more psychiatric diagnoses, work on a new definition – the Fukuda definition began.  (Nobody likes the Fukuda but consider what the last 20 years would have been like using a definition that came closer to labeling ME/CFS as a psychiatric disorder?)

The cure was simply to reduce the number of required symptoms from eight to four. That worked – the number of psychiatric diagnoses dropped into the normal range for chronic illnesses but Fukuda erred by allowing any four of  eight symptoms to qualify  a person for CFS. That meant someone could conceivably qualify for ME/CFS without having  post-exertional malaise, cognitive problems and unrefreshing sleep. That almost certainly meant the Fukuda definition was allowing at least some people into studies who did not have ME/CFS.

The CCC and ICC were designed to fix that fault and the Jason studies have suggested they did.  Two studies indicated that the the ME/CFS patients meeting the CCC and ICC criteria were significantly more cognitively and exertionally challenged than those meeting the Fukuda criteria.

These data suggest that the current case definition for chronic fatigue syndrome inadvertently selects for patients with the highest prevalence of lifetime psychiatric diagnoses Katon and Russo, 1992

Both, however, required that patients have high numbers of very different symptoms. Like the defunct Holmes definition the ICC requires that eight symptoms be present and the CCC requires seven.    Because people with more severe illnesses are probably more likely to have mood disorders an increased rate of psychiatric disorders might be expected in this group but the percentage of psychiatric disorders were so much higher in both the CCC (58%) and ICC selected groups (61%) compared to the Fukuda group (27%) that more than illness severity must have been in play.

Indeed, in an analysis between the CCC and the London ME definition, Jason suggested that the definition itself, not the  increased severity was probably, although not certainly, the reason for the increased rates of psychiatric disorders.

The lack of differences on the psychiatric items suggests that the ME (definition) criteria selects individuals with less psychiatric co-morbidity and mental health issues than the ME/CFS (CCC criteria) group. Jason et al. 2012

Could the Canadian Consensus Criteria Miss Patients with Brain Disorders?

Since the CCC/ICC do surely delineate a more ME/CFS-like set there’s also the potential for more physiological findings but if Dr. Natelson’s work is correct these definitions could also select out a group with fewer neurological findings.

Should the community choose the known problems of the Fukuda definition or the possible consequences of the CCC?

Should the community choose the known problems of the Fukuda definition or the possible consequences of the CCC?

Dr. Natelson’s work over the past 15 years suggests that ME/CFS patients without mood disorders have a specific type of  brain disorder that patients with mood disorders do not have.  Patients without mood disorders appear to have significantly more neurological impairments, functional impairments, reduced blood flows to the brain, lesions on the brain, etc. than patients with mood disorders. Since the CCC/ICC appears to select for patients with mood disorders it’s possible  that they select against patients without mood disorders. In any case, the percentage of patients without mood disorders could drop dramatically and that could make spell hard times for researchers like Dr. Natelson who are looking for evidence of central nervous system damage in this disorder.

Both the DePaul studies have flaws and it’s possible that further, more definitive studies will not find increased rates of mood disorders in CCC defined patients. On the other hand it’s possible that they will. The point is that we don’t know and do we want to take that chance?

The steady stream of psychiatric based ME/CFS studies from Europe and the UK suggests researchers would be eager to exploit any advantage that would allow them to define this disorder as a psychiatric one. The implementation of the new DSM-V criteria potentially opens the door more for psychiatric diagnoses as well.  This is not a time to give psychologically oriented researchers more ammunition.


The letter calls for the adoption of the CCC now with the idea of a transition to a better definition as it becomes available.  on the face it that sounds reasonable but history does not suggest  that the federal government is interested in transitions in this area. Despite the acknowledgement embedded in the Fukuda definition that it was an interim definition, but in the 20 years that definition (nobody seems to really like) has been in force,  the federal government has not tinkered or even funded studies designed to transition to a new definition.

It would undoubtedly take a major effort – spread across multiple agencies, including the  NIH/CDC, FDA, Social Securit, Medicare/Medicaid – to endorse and transition to a new definition. Since that kind of effort probably wouldn’t happen very often it would be much better to gather consensus and data and get it right the first time.

A good statistically based definition may not be that far away.

A good statistically based definition may not be that far away.

Not Far From the Right Definition

We’re actually not that far from a suitable definition that avoids the psychiatric disorder question. Jason found that an ME definition based on Ramsay’s criteria it picked out a more severely ill group of patients than the Fukuda definition without plucking out patients with increased rates of psychiatric illness.  The difference – that definition required just four symptoms; sudden onset, post-exertional malaise, one neurocognitive symptom and one autonomic symptom. The sudden-onset requirement ruins the definition for me but this definition demonstrates you can narrow in on an ME/CFS group without requiring alot of symptoms.

Note that a definition with fewer symptoms does not dis-include people with psychiatric disorders; it simply ensures that people with fewer symptoms and presumably fewer psychiatric disorders also fit the definition.

The End of Consensus Definitions (?)

Diagnostic criteria should be based on statistical methods rather than consensus declarations. Ongoing discussions about which case definition to employ miss the point that the criteria did not pass appropriate external validation. Maes et al. 

The Holmes, Fukuda,  Oxford, Empirical, CCC, ICC….. in fact, all the definitions for ME/CFS produced thus far are consensus definitions put together by groups of people who think they know what ME/CFS looks like.  It’s questionable whether consensus definitions  are going to cut it anymore.  My guess is that science is too data driven now for the federal government to put it’ stamp of approval on another consensus definition.. My guess is that attempting to push the federal government to insert something that radically redefines ME/CFS research efforts and other federal programs is going to require statistical evidence.

The best approach at this point might be to  press the federal government to have the workshop on producing a new definition and provide a funding set aside for studies that statistically determine the best definition for ME/CFS.  Lenny Jason has already done a good deal of work in this area and the feds have shown some interest.  We may not be that far from a definition that everybody can support and which the federal government can take action on. I suggest that we wait for more studies from Jason and others before we endorse a definition at this point.

Take the Canadian Consensus Criteria Poll

Who Ruffles Feathers Better? 🙂

Support Health Rising


Like the blog you're reading? Don't miss another one.

Get the most in-depth information available on the latest ME/CFS and FM treatment and research findings by registering for Health Rising's free  ME/CFS and Fibromyalgia blog here.

Stay on Top of the News!

Subscribe To Health Rising’s Free Information on Chronic Fatigue Syndrome (ME/CFS), Fibromyalgia (FM), Long COVID and Related Diseases.

Thank you for signing up!

Pin It on Pinterest

Share This