Deconstructing post-exertional malaise in myalgic encephalomyelitis/ CFS: A patient-centered, cross-sectional survey, Chu et al, 2018

Indigophoton

Indigophoton

Senior Member (Voting Rights)
Background
Post-exertional malaise (PEM) is considered to be the hallmark characteristic of myalgic encephalomyelitis/ chronic fatigue syndrome (ME/CFS). Yet, patients have rarely been asked in formal studies to describe their experience of PEM.

Objectives
To describe symptoms associated with and the time course of PEM

Methods
One hundred and fifty subjects, diagnosed via the 1994 Fukuda CFS criteria, completed a survey concerning 11 symptoms they could experience after exposure to two different types of triggers. We also inquired about onset and duration of PEM and included space for subjects to write in any additional symptoms. Results were summarized with descriptive statistics; McNemar’s, paired t-, Fisher’s exact and chi-square goodness-of-fit tests were used to assess for statistical significance.

Results
One hundred and twenty-nine subjects (90%) experienced PEM with both physical and cognitive exertion and emotional distress. Almost all were affected by exertion but 14 (10%) reported no effect with emotion. Fatigue was the most commonly exacerbated symptom but cognitive difficulties, sleep disturbances, headaches, muscle pain, and flu-like feelings were cited by over 30% of subjects. Sixty percent of subjects experienced at least one inflammatory/ immune-related symptom. Subjects also cited gastrointestinal, orthostatic, mood-related, neurologic and other symptoms. Exertion precipitated significantly more symptoms than emotional distress (7±2.8 vs. 5±3.3 symptoms (median, standard deviation), p<0.001). Onset and duration of PEM varied for most subjects. However, 11% reported a consistent post-trigger delay of at least 24 hours before onset and 84% endure PEM for 24 hours or more.

Conclusions
This study provides exact symptom and time patterns for PEM that is generated in the course of patients’ lives. PEM involves exacerbation of multiple, atypical symptoms, is occasionally delayed, and persists for extended periods. Highlighting these characteristics may improve diagnosis of ME/CFS. Incorporating them into the design of future research will accelerate our understanding of ME/CFS.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0197811
 
I admit to on!y reading the abstract but:

One hundred and twenty-nine subjects (90%) experienced PEM with both physical and cognitive exertion and emotional distress.
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Is it normal to experience emotional distress as part of PEM?

In the early days I got upset because I just couldn't figure out what the hell was happening, but this was a consequence of PEM not part of it.

Nowadays, it naffs me off, but I don't find it distressing so much as frustrating. Sometimes, not even that as I know it it's just part and parcel of having ME.
 
I read that as, both physical and cognitive exertion and emotional distress caused PEM for 90% of people in the study. It then goes on to say, "Almost all were affected by exertion but 14 (10%) reported no effect with emotion", and "Exertion precipitated significantly more symptoms than emotional distress..."
 
Properly defining PEM is extremely important – all too often it seems to get confused with plain exercise intolerance - so I appreciate the efforts by the authors.

Unfortunately the article is too long for me to read in full so can't comment on how well they have achieved this but I was puzzled by this apparent contradiction:

First the authors capably discuss the various diagnostic criteria including the problem with Fukuda – i.e. that PEM is optional.

But then they use Fukuda (PEM optional) to select patients for their own study that has as its express purpose to explore PEM???!!!

Have I missed something that explains this?
 
My assumption would be that they didn't want to presuppose anything about PEM, or at least no more than was unavoidable. This seems to be borne out by a section discussing limitations of the study:
During the recruitment process, we screened subjects using the Fukuda criteria. Although subjects did not have to have PEM to qualify for the study, 99% of subjects responded affirmatively when asked if they had PEM. Thus, despite our efforts to obtain an unbiased picture of PEM without evoking existing definitions or accounts of PEM, some subjects’ reports of PEM might have been unduly influenced by what they had read or heard previously. In the future, this might be remedied by prospectively interviewing patients at risk for ME/CFS, e.g. soon after an episode of Epstein-Barr infectious mononucleosis, before they have heard of or have become familiar with the term PEM, rather than retrospectively.
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I’ve read this and I like, it mainly because it goes way beyond fatigue and properly defines PEM with key symptoms. It is an informed definition of PEM with defined triggers, symptoms and timeframes using a reasonably sized cohort. Worth a read.

“The overwhelming majority (90%) of subjects experienced PEM with physical/ cognitive exertion and emotional upheaval. Aggravation of multiple symptoms, a median of 7 and 5, respectively, was the rule rather than the exception. For 8 out of 11 symptoms, at least a third of subjects encountered them under either situation (Table 1). Some symptoms are commonly observed with physical exertion even in healthy people (e.g. muscle pain) while others are atypical (e.g. flu-like feelings, gut-related symptoms, sensory overload), neither reported by healthy people nor people affected by other medical conditions. Because our questionnaire listed specific symptoms rather than combinations (e.g. “sore throat/ tender lymph nodes” [35]) or categories of symptoms (e.g. “autonomic” [36]), a direct comparison to Workwell’s findings is not possible. Nevertheless, the multitude of symptoms recollected by our subjects reflect those of Workwell’s subjects. For example, fatigue-, pain-, and sleep-related symptoms were the top 3 categories noted by Davenport [36], analogous to the first, fourth, and fifth most common symptoms observed by us post-exertion (fatigue, muscle pain, sleep disturbances). Other symptom combinations they used such as “light-headedness/ vertigo” were not a part of the 11 symptoms we listed but emerged in the open-ended portion of our questionnaire.”
 
There's a lot of good stuff in here, especially how they describe PEM in the discussion section.

the concurrence and type of symptoms aggravated are a strong clue to PEM. Post-exertional fatigue, muscle pain, and joint aches are very common after even minor activity in many people so mere presence of these three symptoms may not help clinicians recognize PEM. However, other symptoms associated with PEM are either not usually linked to exertion/ emotional distress or even paradoxically improved by physical exertion in persons unaffected by ME/CFS. For example, there exists no medical condition the authors are familiar with where exertion or emotional distress causes immune/ inflammatory-related symptoms like sore throat, tender lymph nodes, or flu-like feelings, yet 60% and 36% of our subjects, respectively, reported these symptoms with either stimuli and about a quarter experienced all 3 with exertion.
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it is well-established that physical activity improves mood, sleep, and pain in both healthy people as well those with chronic illnesses like depression or anxiety [47–49] yet our subjects report worsened sleep, mood, and pain with physical activity. This paradoxical effect is also demonstrated by studies which focus on the physiological aspects of ME/CFS
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PEM has an unusual time course. In many medical conditions, exertion-exacerbated symptoms usually start during exertion or immediately after and usually resolve immediately or shortly after exertion stops. In contrast, PEM may not start until hours or even days after the trigger starts or has been removed, may peak after the first day, and may not stop until hours to months later.
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But I do think they could have done more and better with their own study and method.

They could have enrolled patients diagnosed via International consensus or Canadian criteria, not Fukuda, thus making sure patients were actually likely to have true PEM (though that probably still isn't 100% certain unless the diagnosing clinician is experienced enough to not confuse PEM and exercise intolerance – part of the point of the paper). As a bonus, this would also send a signal to other, maybe less well-informed researchers to stop using Fukuda almost as a reflex. While they're at it, they could stop using those pointless Fatigue score questionnaires with questions so vague they cannot possibly be answered in any meaningful way. (This is discussed in @Trish's members only thread on FSS – also used in the present study - “How would you fill in the Fatigue Severity Scale?”)

Alternatively they could have stratified their enrolled patients into those who meet International/Canadian and those who only meet Fukuda and reanalyse their data separately. This could potentially have shown differences in how PEM is reported, qualitatively or quantitatively. It might also have explained the discrepancy between their own findings and Workwell's.

Applying the Workwell Foundation’s findings [36], only 42% of our subjects qualified for their “4-symptom PEM” schema. A different set of symptoms, perhaps accompanied by severity ratings, may be needed in order to detect PEM in more patients.
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This raises – but doesn't answer - the question whether it actually was only 42% of their subjects who experienced “true” PEM and the others experienced various versions of exercise intolerance symptoms? A bit like the difference between strictly defined ME and more broadly defined CFS maybe? Or whether their idea that a different set of symptoms may detect more cases of PEM is correct. I was for example surprised their chosen 11 symptoms didn't include orthostatic intolerance or tachycardia.

In summary, the discussion of PEM in this paper is excellent. The actual study is a little disappointing because it doesn't add a great deal new, though it's always good to confirm findings from prior research, especially when that research is still a bit sparse.
 
Lily Chu has been quietly and humbly being our champion and ally for so many years, and I am continually blown away by her contributions. Of course it goes without saying that so have Montoya et al, but I wanted to take a moment to offer a much-deserved shout-out to Ms. Chu who has stayed the course and keeps showing up for us in so many different powerful ways. Thank you Lily Chu!:trophy@:angel:
 
Out of curiosity, is there a clear definition of flu-like feelings and sensory overload?

Does flu-like feeling refer to a specific kind of sensation that appears in the flu (together with less specific sensations such as malaise, fatigue, fever) or is it a term used to describe how you feel during an infectious illness?

What is sensory overload exactly?
 
Allele said:
Lily Chu has been quietly and humbly being our champion and ally for so many years, and I am continually blown away by her contributions. Of course it goes without saying that so have Montoya et al, but I wanted to take a moment to offer a much-deserved shout-out to Ms. Chu who has stayed the course and keeps showing up for us in so many different powerful ways. Thank you Lily Chu!:trophy@:angel:
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I agree. She was a great help to me in 2010-2011 with my paper:
"Reporting of Harms Associated with Graded Exercise Therapy and Cognitive Behavioural Therapy in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome"
http://iacfsme.org/PDFS/Reporting-of-Harms-Associated-with-GET-and-CBT-in.aspx

A small correction: she is a qualified medical doctor so best to call her Dr Chu
 
Ravn said:
It might also have explained the discrepancy between their own findings and Workwell's.

Applying the Workwell Foundation’s findings [36], only 42% of our subjects qualified for their “4-symptom PEM” schema. A different set of symptoms, perhaps accompanied by severity ratings, may be needed in order to detect PEM in more patients.
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This raises – but doesn't answer - the question whether it actually was only 42% of their subjects who experienced “true” PEM and the others experienced various versions of exercise intolerance symptoms?
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I imagine a big contributing factor to the discrepancy is that the Workwell Foundation studies involved repeat exercise testing. That is an extreme exertion that many people would avoid.
 
Ravn said:
I was for example surprised their chosen 11 symptoms didn't include orthostatic intolerance or tachycardia.
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People could add other symptoms. Here are the others mentioned:
Outside of the 11 symptoms listed, some subjects also cited gut- (e.g. nausea, irritable bowel; N = 6 and 5, respectively, with exertion vs. emotional distress), orthostatic- (e.g. dizziness, pre-syncopal feelings; N = 4, 3), mood- (e.g. anxiety, depression; N = 4, 4), nervous system- (e.g. sensory overload, tingling skin; N = 12, 7), pain- (e.g. sinus pressure; N = 7, 5), respiratory- (N = 2, 2) and “infection”-related (N = 3, 2) symptoms as components of their PEM.
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