Scartozzi, Sunnquist, Jason (2019). ME/CFS case definitions: Effects of requiring a substantial reduction in functioning.

[Lucibee]

From Leonard Jason's FB wall:

Just published online from the DePaul group in our continuing efforts to examine critical issues and assumptions regarding the case definitions.

Scartozzi, S., Sunnquist, M. & Jason, L.A. (in press). Myalgic Encephalomyelitis and Chronic Fatigue Syndrome case definitions: Effects of requiring a substantial reduction in functioning. Fatigue: Biomedicine, Health & Behavior. Published online April 1, 2019. doi: 10.1080/21641846.2019.1600825

ABSTRACT
Background: Current case definitions for myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS) require an individual to report a ‘substantial reduction’ in activity levels, when compared to premorbid functioning. However, little guidance is provided on how to measure these reductions, as well as what level of reduction should be deemed ‘substantial,’ leading to inconsistencies in how this criterion is applied across research settings.

Purpose: The current study examined the influence of substantial reduction criterion on case definitions.

Method: The current study analyzed an international convenience sample of 1002 individuals with ME or CFS, 53 healthy controls, and 260 controls with other chronic illnesses.

Results: Findings indicated that the utility of the substantial reduction criterion varied by case definition, with more stringent case definitions not needing this criterion to identify cases.

Conclusion: These results suggest that the requirement of a substantial reduction in functioning may be redundant when case definitions specify that individuals must endorse a set of core symptoms at specified frequency and severity levels.

From the Introduction:
"While several researchers have attempted to specify measurement rules for assessing substantial reductions in functioning, no study has explicitly examined the diagnostic utility of this criterion. Its inclusion in case definitions may have been inspired by psychiatric literature, as diagnostic criteria for other chronic medical illnesses do not include criteria related to activity reductions from premorbid functioning [e.g. 13–16]. In contrast, this requirement has been included in psychiatric diagnostic criteria within the Diagnostic and Statistical Manual of Mental Disorders (DSM), in versions that predate the first ME and CFS case definitions (e.g. the DSM-III-R) [17]. In the latest version of the manual, the DSM-5 [18], the following phrase is included as a diagnostic criterion for numerous disorders: ‘symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.’ As individuals with ME and CFS often report experiences during which others suggest that their symptoms are psychological [19], using a criterion associated with psychiatric diagnoses could perpetuate their experiences of stigma."

 

[Lisa108]

sci-hub link

 

[Ravn]

Two comments:

1/ They missed the most important effect of "requiring a substantial reduction in functioning" which is that more mildly affected patients don't get an early diagnosis and with it appropriate advice about pacing and so risk becoming worse.

2/ This doesn't seem right: Well above a third of the ill controls in the study supposedly met CCC and ICC, requiring participants to report PEM. Even some of the healthy controls met the criteria which makes me wonder how healthy they actually were.

I suspect what they were really measuring was post-exertional fatigue, not post-exertional malaise.

Their ill control group included lupus, MS, post-polio and cancer. I know people with all those conditions and all of them have post-exertional fatigue to some degree, some quite badly. But none of them have post-exertional malaise.

 

[WillowJ]

I am not sure that post-polio (or post-SARS or post-whatever-infectious-disease) is a different disease from ME.

I am sure that people with lupus, MS, RA, and other diseases can have post-exertional fatigue, but I don't know what other symptoms some of them might have. I mostly hear about fatigue and pain, but I have not done or read a systematic survey.

I think if we define post-exertional malaise very carefully, it might be unique to us, but I don't think we have the evidence to say for sure. Some people who thought they had ME with PEM have been diagnosed with other things and think the new diagnosis suits better.

So I don't think we can be sure of anything yet, except that fatigue or even post-exertional fatigue is a bad sorter for ME/cfs.

 

[rogerblack]

Merged thread

https://www.ncbi.nlm.nih.gov/pubmed/31788347 A paper on on if removing 'substantial reduction' from the diagnostic criterai is useful.

Given the ambiguous nature of the sub-stantial reduction criterion, as well as its potentially stigmatizing association with psychia-tric diagnosis, future research should continue to evaluate this criterion’s inclusion in casedefinitions, as results of this study suggest that the criterion is redundant when casedefinitions require specific, cardinal symptoms of ME and CFS.

Does anyone find 'substantial reduction' stigmatising? Even if it did originate in psychological diagnosis. (?)

Conclusion:These results suggest that the requirement of asubstantial reduction in functioning may be redundant when casedefinitions specify that individuals must endorse a set of coresymptoms at specified frequency and severity levels.

As the conclusion states - with some case definitions - specifically CCC and IOM - the cost of removing it is small.
(But I'm not sure why you'd want to).

 

[ME/CFS Skeptic]

As the conclusion states - with some case definitions - specifically CCC and IOM - the cost of removing it is small.

It has sometimes been said that fatigue is a continuum and that ME/CFS just forms an artifical part at the severe end. Patients are very ill because case definitions require them to be.

So if I remember correctly, this paper was relevant in showing that requiring a substantial reduction in functioning does not fully explain why ME/CFS patients are so ill, as in some case defintions this apparentlh changes little to the selection of patients.

 

[Dolphin]

The paper doesn’t mention that with changing times, more people will have data from actometers of one sort or another. These in theory could provide a baseline against which current activity levels might be compared.

 

[Dolphin]

Two comments:

1/ They missed the most important effect of "requiring a substantial reduction in functioning" which is that more mildly affected patients don't get an early diagnosis and with it appropriate advice about pacing and so risk becoming worse.

Yeah.

I suspect the requirement of a 50% reduction one sometimes hears may not be appropriate, at least in a clinical setting (stricter criteria for research studies can be justified).

 

[Dolphin]

This is that the only table of data in the paper, apart from one giving demographic information:


It's interesting to see the relatively low numbers of (apparently) "healthy controls" who satisfied the Institute of Medicine criteria, and that the figures are lower than for the Canadian ME/CFS criteria.

It's also interesting to see how how much the Fukuda criteria depend on "substantial reduction in activity"; without them their specificity(s) is/are very bad, though might improve with the use of frequency and severity thresholds like those required with the Institute of Medicine criteria.