An Interview with Dr. Leonard Jason on the New Prevalence Estimates and the Empirical Definition for Chronic Fatigue Syndorme by Cort Johnson (August 2007)
Dr. Jason has had a profound impact on how we view CFS. An epidemiologist, Dr. Jason lead the Pediatric definition group, produced the first complete economic costs estimate of ME/CFS, was instrumental in coming up with the correct prevalence estimates and has highlighted the central role post-exertional and cognitive problems play in ME/CFS. He is a board member of the IACFS/ME and a committee member of the Chronic Fatigue Syndrome Advisory Committee. He was a major author of the International Chronic Fatigue Syndrome Group (ICFSG) paper that provided the CDC with recommendations for the Empirical definition. The CDC took the recommendations and then used an in-house team to create the new definition.
Dr. Jason was good enough to chat with me regarding the startling new prevalence figures and the Empirical Definition for CFS and the consequences it may have for CFS research.
(The Empirical Definition and the 2007 Prevalence Study are in the public domain. You can access them by clicking on each phrase. An overview of the new definition can be found at the Defining CFS page.)
(1) This definition seems more revolutionary than evolutionary; it raises prevalence figures enormously, it no longer relies solely on symptoms, it uses standardized testing, it discounts fatigue and pain and introduces emotion as a potential contributor to a CFS diagnosis for the first time. It almost seems like we’re starting over – like this is a sort of a ‘Brave New World’ for CFS. Is this something we might look back at in 10 or 15 years and say that event substantially changed the course of CFS research?
You certainly raise concerns and I have done so as well.
Dig Deeper! Defining ME/CFS.
(2) Symptoms: This is the first definition I am aware of that doesn’t define CFS using symptoms. The CDC has tried and failed find a unique symptom set in CFS patients as opposed to chronically fatigued or unwell patients. Several other groups that tried to do the same thing had mixed results and failed to replicate each other. You were a major author of the recommendations paper that proposed using indices of fatigue, disability and symptom severity to define CFS. Can we say that CFS patients do not have a unique set of symptoms as opposed to other people with chronic fatigue? Is the search for a symptom based definition of CFS over?
I disagree. The cardinal symptoms are assessed in the Canadian criteria, and that seems like a very worthy direction for the future.
(3) The Use of an Emotional Subscale. You’ve demonstrated this is the first definition in which someone reporting emotional but not necessarily physical distress can fulfill the disability criteria for CFS. Do you believe that physical distress is an inherent part of CFS or should the definition of CFS be opened to include patients whose disability arises from emotional problems as well?
I think the issue is that if one only has emotional distress, it would signal that a person could meet the disability criteria. That is the problem.
(4) Excluding Depressed Patient Without CFS . There is a world of difference between someone who has restricted his or her activities because they know that being too active will cause them to ‘crash’ (CFS) and someone who is inactive because they don’t feel they have any reason to be active; (major depression). Can tests distinguish between people with CFS who are depressed and people who are depressed but don’t have CFS?
Yes, they can and it can be done with high reliability as a recent paper I published indicated. (The reference is below). (A anonymous CFS/ME graduate student has offered a rebuttal to this statement. In a family portrait he/she draws he provides an fascinating look at the intersection between infection, CFS and emotional distress. )
(5) Post-Exertional Malaise. I have always personally felt post-exertional malaise (PEM) to be the hallmark symptom of CFS. Everything else; the fatigue, concentration problems, muscle pains, dizziness, etc. are kind of nebulous compared the dramatic changes I experience when I exercise. Some of your studies, and if I am reading them right, some CDC studies have suggested PEM is an important symptom in CFS but others have not. PEM is also found in other diseases including major depression. What role do you believe PEM plays in CFS and what role should it be given in a definition of CFS?
You might want to check out the Canadian criteria, as they have it right on this important issue. The problem with Fukuda et al. (19940 as well as the new empirical case definition is that you can not have this symptom and still get the CFS diagnosis.
(6) Fatigue in CFS? Fatigue is taking more a back seat in this new definition. Dr. White noted that under this definition ” it would be possible to meet the fatigue criterion without significant fatigue”. Simply scoring low on the activity subscale allows one to meet the ‘fatigue’ criteria for CFS. Dr. Reeves has noted that as he’s learned more about CFS he’s found that ” Many people have more problems with pain, memory or concentration than they do with fatigue”. Many in the CFS community have, in fact, railed against the emphasis given to fatigue in CFS. Should fatigue be given a less prominent role in defining CFS?
Fatigue is too general, but post-ex malaise is the key piece. Some do not experience fatigue anymore because they try to avoid doing too much. It is a lack of endurance, stamina, or energy that can be sustained that is the key issue.
(7) You don’t need to be that much less active or that fatigued to meet the ‘fatigue’ criteria for CFS; you simply need to score on the median or below. But it’s hard to imagine how a median level of fatigue or activity is severe enough to result in the ‘ substantial reductions in previous levels of occupational, etc. activities’ the Fukuda definition called for let alone it’s concept of -‘ severe mental and physical exhaustion’. Doesn’t this throw what’s been considered a basic aspect of CFS out the window?
I agree with your assessment.
(8) A Step Forward or a Step Back? The big concern for CFS patients is that if there is a unique disorder called CFS and you add all these other diseases in the mix then the search for a biomarker just gets that much harder. One could argue that by allowing a subset of non-CFS patients into CFS research studies that the Fukuda definition set back CFS research and its search for legitimacy by years. Do you believe there’s a big danger in this new definition?
Yes, and I have stated this.
(9) If these diseases (CFS, PTSD, MDD, FMS, IBS) have different physiological origins – and based on the evidence thus far one must assume that, at least in part, that they do – and you throw them all into one pot then you run the risk of simply left with symptoms and complaints – for which you can’t show a cause plus increased rates of mood disorder. This seems like a situation which could over time lead to CFS increasingly being cast as some sort of mood disorder. Do you see this as a possibility with this new definition?
Mood disorders are one of the more common psychiatric set of disorders. Yes, I am most concerned about this, as I have previously stated.
(10) An Opportunity? Dr. Reeves stated that the most important part of the definition is not the specific criteria but the fact that there are, for the first time, measurable criteria. If researchers do use the SF-36, MFI and Symptom Severity tests won’t they be able to tell if distinct subgroups are showing up? Shouldn’t we be able to tell, for example, if a depressed group without post-exertional fatigue shows up? Could the better characterizations implicit in the new definition help us find the subsets researchers have been speculating about for years and perhaps even contribute to the breakup of the CFS label?
With criteria this broad, you might be diagnosing people with chronic unwellness, and then you will have to try to differentiate these groups into other subgroups.
(11) Excluding Mood Disorders? They ICFSG produced a long list of exclusionary factors designed to prevent people who have other diseases from participating in CFS research studies. Among them were a rather long list of psychiatric diagnoses including a diagnosis of major depressive disorder (with melancholia/psychosis) within the past five years. Won’t these exclusionary factors protect CFS research studies from being swamped with people with mood disorders?
Check closely the new CDC papers. They do not use this criteria.
(The CDC has used the same general group of patients (‘Surveillance Study Group’) for most of its studies of the past five years. This group included patients with major melancholic depression (MMD) – a disease that both the Fukuda and Empirical Definition exclude from participating in research studies.
Some of these studies have included the MMD subset and others have not. The Pharmacogenomic’s studies all appear to have included them. Studies on symptoms, child abuse, the glucocorticoid receptor polymorphisms, sleep and the Empirical definition and Prevalence studies excluded them. The Prevalence study used a different group of patients and excluded MMD patients.
Only the most severe form of depression – melancholic depression – is exclusionary for CFS. ‘Regular’ depression, anxiety disorder and somatoform disorders are not).
(12) Another Smoke-filled Room. It seemed ironic that not long after Dr. Reeves characterized the Fukuda definition as being produced by a group of people in a smoke filled room that the new definition was produced in much the same way. The CDC convened a representative and varied group of CFS professionals to work on the broad recommendations for the new definition but then turned over the actual creation to a small group of CDC researchers who have, thus far, hardly been forthcoming regarding their decision making process. The CDC brought you together to provide recommendations -did they explain why they didn’t do that during the critical definition building process?
We have not been informed of this. But you have asked the key question.
(12) A Surprising Outcome. Your studies help build the foundation for a new definition. They suggested that simple definitions like the Fukuda (International) definition can allow people with emotional disorders (but not CFS) entry into CFS research studies. They’ve also indicated that using measures of symptom severity (rather than simply occurrence) and tests like the SF-36 make it less likely that this type of misdiagnosis will occur. Both of these tests are found in the new definition but you, ironically, are more concerned than ever about people without CFS getting into CFS research studies. This can’t be what you envisioned when you signed off on the ICFSSG recommendations? Were you surprised at the direction the definition finally took?
Yes I was very surprised.
(13)The IACFS. If this really has the potential to be a kind of paradigm changing event isn’t this something that our professional organization – the IACFS – should weigh in on? They published your letter but shouldn’t they take a formal stance towards an issue of this significance?
I have tried to raise the issue, but am just one board member. As you know, the board has allowed me to post my views on the IACFS/ME website.
(14) A Done Deal? There’s a great deal of worry about the new definition but given the CDC’s dominance with regard to CFS definitions are we, for better or for worse, already living in world defined by it? Is it inevitable that this new definition will become the gold standard for the research community?
I hope not.
(Hawk, C., Jason, L.A., & Torres-Harding, S. (2006). Differential diagnosis of chronic fatigue syndrome and major depressive disorder. International Journal of Behavioral Medicine, 13, 244-251.)