Firestormm
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Contrasting Case Definitions for Chronic Fatigue Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Myalgic Encephalomyelitis
Note: Link gives access to full paper
One way in which the CCC was operationalised - something that the IOM has said a criteria is in need of I recall - was by Jason. He applied a measure of severity and frequency. Currently the 2003 CCC and other criteria, merely ask if you have a symptom, not how often you have it occur...
I don't have the time or really the inclination to review this paper properly. Indeed I probably read it when it was published - but have forgotten the salient points now.
Here's a few highlights from a quick read through. The issue of selecting an existing criteria is clearly not a straightforward one, and even Fukuda appears to have some benefits.
I'm not sure if Jason has published the study he refers to in my 'conclusion' at the bottom, but if he has then it might also be something the IOM should consider.
Incidentally, the Statement of Work from HHS, refers to a 'Revised Canadian ME/CFS Definition' published in 2010 - and not something referred to by the experts - as another criteria they want or feel is in need of consideration as part of the IOM remit.
This is again another paper from Jason (thanks @Ember for finding where it had been referenced ) but I haven't yet read it or considered what impact it might have on the 2003 Canadian Criteria - even if I was so inclined.
And then of course you have the NICE criteria encapsulated in it's 2007 Clinical Guideline and the ME ICC published in 2011. Both of which are also up for consideration by the IOM committee.
Anyways...
Note: Link gives access to full paper
One way in which the CCC was operationalised - something that the IOM has said a criteria is in need of I recall - was by Jason. He applied a measure of severity and frequency. Currently the 2003 CCC and other criteria, merely ask if you have a symptom, not how often you have it occur...
To operationalize the Canadian clinical ME/CFS case definition, we used data from the CFS Questionnaire to assess how often the person had experienced the symptom (fatigue, postexertional malaise, etc.) over the past 6 months using the following scale: 0 = never, 1 = seldom, 2 = often or usually, 3 = always.
To be counted as “persisted or recurred,” the individual had to have a frequency score of 2 or higher (See Jason, Evans et al., 2010). In addition, it is important that fatigue and the other core symptoms were either moderate or severe on a 100-point scale.
This “severity index” has not been well defined in previous ME/CFS criteria. We now specified that existing symptoms need to be rated at a 50 (as moderate) or higher to meet criteria. Both ratings of frequency and severity, therefore, had to be satisfied in order to qualify for each individual symptom.
I don't have the time or really the inclination to review this paper properly. Indeed I probably read it when it was published - but have forgotten the salient points now.
Here's a few highlights from a quick read through. The issue of selecting an existing criteria is clearly not a straightforward one, and even Fukuda appears to have some benefits.
I'm not sure if Jason has published the study he refers to in my 'conclusion' at the bottom, but if he has then it might also be something the IOM should consider.
Incidentally, the Statement of Work from HHS, refers to a 'Revised Canadian ME/CFS Definition' published in 2010 - and not something referred to by the experts - as another criteria they want or feel is in need of consideration as part of the IOM remit.
This is again another paper from Jason (thanks @Ember for finding where it had been referenced ) but I haven't yet read it or considered what impact it might have on the 2003 Canadian Criteria - even if I was so inclined.
And then of course you have the NICE criteria encapsulated in it's 2007 Clinical Guideline and the ME ICC published in 2011. Both of which are also up for consideration by the IOM committee.
Anyways...
Discussion
...Table 2 indicates that both the ME/CFS and the ME groups had more impairment than the comparison Fukuda CFS groups. In addition, the most impairment on physical issues involved the ME group.
We did not directly contrast the ME/CFS and ME groups, but in general, impairment was significant for both groups. In addition, the ME group appears to have less mental health issues than the ME/CFS group.
It does appear that requiring specific criteria, such as what occurs in the ME and ME/CFS case definitions, does select individuals with more functional disabilities.
In the original Canadian ME/CFS criteria (Carruthers et al., 2003), symptoms could be rated as mild, moderate or severe, but it was unclear whether symptoms needed to meet specific frequency and severity levels to be counted.
In other words, it was possible to count just whether symptoms occurred in order to meet the ME/CFS criteria. Had just occurrence of symptoms been employed (rather than needing to meet cutoff scores for frequency and severity of symptoms) for the core ME/CFS Canadian criteria symptoms in Table 3, 105 of the individuals in the current sample (over 90%) would have met ME/CFS criteria.
However, when using the symptom frequency and severity cutoff points as specified by Jason et al. (2010), only 50% met the ME/CFS criteria. It is clear that these individuals with ME/CFS had more severe functional disability and symptoms than the Fukuda CFS {a} group....
In the present study, we found significantly higher current psychiatric comorbidity rates for those with ME/CFS versus Fukuda CFS {a} (58% vs. 20%). In the prior study, using just symptom occurrence to classify patients, Jason et al. (2004) found that the ME/CFS group had significantly lower current psychiatric rates (48%) than the Fukuda et al. (1994) CFS group (75%).
It is probable that the current study selected a more seriously impaired group of patients with ME/CFS and that their impairments were across a broad array of both physical and mental health areas. Katon and Russo (1992) have argued that a requirement of more symptoms to meet criteria could inadvertently select for individuals with psychiatric problems.
Similarly, Kroenke (2003) found similar results examining 15 variables within a fatigued sample. Upon examination of 13 of these 15 variables in our sample, we found that a greater number of symptoms was associated with increased psychiatric comorbidity as well as an ME/CFS diagnosis. It is certainly possible that the larger number of symptoms of higher frequency and severity among patients meeting the ME/CFS criteria versus Fukuda CFS {a}, accounts for the higher levels of psychiatric comorbidity and more functional
impairments on the Role Emotional and Mental Health SF-36 subscales among the ME/CFS criteria group.
In contrast, the ME criteria required four versus the seven ME/CFS symptoms to meet its case definition. Of interest, there were no significant psychiatric rate differences for the ME versus Fukuda CFS {b} groups (44% vs. 37%).
There were also no significant differences between the ME and Fukuda CFS {b} groups on the SF-36 scales measuring Role Emotional and Mental Health areas....
...But the lack of differences on the psychiatric items suggests that the ME criteria selects individuals with less psychiatric comorbidity and mental health issues than the ME/CFS group.
It is possible that sudden onset, postexertional malaise, a neurocognitive and autonomic symptom identify individuals with fewer emotional and mental health problems, but when additional symptoms are required, this selects both more physical and mental problems.
It should also be noted that in previous studies that have found more disability/symptoms causing psychiatric problems, there were confounds, with symptoms counting for psychiatric diagnoses.
In addition, there might be a number of reasons for a higher rate of psychiatric disorders associated with more symptoms and/or disability. For example, it could be more “depressing” to have more symptoms and/or disability interfering with what one can do.
Perhaps similarly, one might be more anxious about how one might be able to cope in the future.
Across medical conditions, illnesses/diseases that are more disabling and/or have more symptoms associated with them/interfere with life more are associated with higher rates of psychiatric problems.
Conclusion
The current CFS case definition of Fukuda et al. (1994) has been used internationally by researchers for over 15 years. It is possible that some patients meeting these criteria do not have core symptoms such as postexertional malaise or memory/concentration problems.
By specifying seven symptoms as with the ME/CFS criteria or by specifying four symptoms with the ME criteria, it may be possible to identify a more homogenous and impaired group of patients. The current study suggests that the ME and ME/CFS criteria might be used to identify patients with possibly more homogenous and severe symptomatology and functional impairment.
Some might conclude that the ME/CFS definition requires too many symptoms that may at the upper ends select for psychiatric disorder. Others might feel that we should just expect higher levels of a variety of both medical and psychiatric disorders if this definition is utilized. Still others might feel that the severity dimension be relaxed as in the previous ME/CFS study (Jason, Torres-Harding, Jurgens, & Helgerson, 2004) that did not require such a high level of symptom severity.
The present study suggests that the initial definitions of ME (Dowsett et al., 1994; Goudsmit et al., 2009; Ramsay, 1988) and later on the Canadian criteria of ME/CFS (Carruthers et al., 2003) appear to select a group of patients that have more severe functional impairments, and physical and cognitive symptoms.
The ME/CFS criteria appear to identify more impairments in symptoms, whereas the ME criteria appear to identify more impairment in functional status, except for emotional and mental health domains.
It would be premature to make any definitive conclusion at this time concerning which explanation is more valid. Certainly, there is a need for more research on this topic, with larger data sets. We are currently collecting more data on this issue, and we hope in the future to be able to offer more definitive interpretations of the findings reported in the current study.
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