Simon
Senior Member
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The NIH/CDC are deciding on the “common data elements“, CDEs, that must be collected in all future studies they fund. And they’ve asked for patient comments on the draft proposals by 31 January.
Perhaps the most important of the CDEs covers post-exertional malaise (PEM), the cardinal symptom of the illness. The PEM working group has proposed using the PEM subscale from Lenny Jason’s DePaul Symptom Questionnaire (DSQ). However, I have concerns about its suitability and I’d like to hear what other patients think.
The DSQ will help define who has PEM and who does not (in some studies it will be the only measure used). If it’s inaccurate, it risks including patients who don’t have the illness and excluding those who do, weakening research.
The DSQ assesses PEM by asking patients to rate the severity and frequency of five symptoms over the last six months:
However, I don’t feel that these questions capture the essence of PEM.
In fact, the working group itself has adopted the Institute of Medicine report’s definition of PEM:
Post-exertional malaise is defined as an abnormal response to minimal amounts of physical or cognitive exertion that is characterised by [my summary]:
This looks to me like a good description of PEM but it’s substantially different from the DSQ.
Also, the DSQ asks patients to rate each item in terms of frequency and severity, and only those who get above a relatively high score will be classed as experiencing PEM (e.g. having the problem at least half the time). However, the frequency and severity of PEM depend not only on severity of illness but also on a patient’s level of exertion. Most patients pace themselves very carefully to try to avoid PEM, and those who do would be appear not to have PEM and would be excluded from every NIH and CDC study.
The working group are aware of this problem and talk about having researchers ask supplemental questions (e.g. the effect if/when they engage in physical or mental activity and whether there are activities they avoid because it exacerbates symptoms). But surely the better approach would be to use a questionnaire that asks patients directly what happens if they exert themselves, in order to reveal whether they have PEM?
If other patients share my concerns, then we need a clear plan from the NIH/CDC to urgently develop a replacement questionnaire, based on input from patients.
So I’d appreciate any answers to these questions:
IMPORTANT. This is not intended as a criticism of Professor Leonard Jason, who has been a lonely pioneer of case definitions and PEM in particular. Without his and his team’s research there would be nothing to use now, and we do need something in the interim. Nor is this a criticism of the working group (co-chaired by Lily Chu and patient-advocate Mary Dimmock). This group has produced many good recommendations and has highlighted many of the weaknesses of the DSQ.
This, though, is about how PEM will be defined in every NIH and CDC study, including every biomedical study, so it needs to be as good as it can be, as soon as possible, to produce the best possible research.
Perhaps the most important of the CDEs covers post-exertional malaise (PEM), the cardinal symptom of the illness. The PEM working group has proposed using the PEM subscale from Lenny Jason’s DePaul Symptom Questionnaire (DSQ). However, I have concerns about its suitability and I’d like to hear what other patients think.
The DSQ will help define who has PEM and who does not (in some studies it will be the only measure used). If it’s inaccurate, it risks including patients who don’t have the illness and excluding those who do, weakening research.
The DSQ assesses PEM by asking patients to rate the severity and frequency of five symptoms over the last six months:
- Dead, heavy feeling after starting to exercise.
- Next day soreness or fatigue after non-strenuous, everyday activities.
- Mentally tired after the slightest effort.
- Minimum exercise makes you physically tired.
- Physically drained or sick after mild activity.
However, I don’t feel that these questions capture the essence of PEM.
In fact, the working group itself has adopted the Institute of Medicine report’s definition of PEM:
Post-exertional malaise is defined as an abnormal response to minimal amounts of physical or cognitive exertion that is characterised by [my summary]:
- A flare of some or all of an individual’s symptoms,
- with an immediate or delayed onset and
- with prolonged recovery.
- Severity and duration of symptoms are out of proportion to the initial trigger.
- There is a loss of functional capacity and/or stamina.
This looks to me like a good description of PEM but it’s substantially different from the DSQ.
Also, the DSQ asks patients to rate each item in terms of frequency and severity, and only those who get above a relatively high score will be classed as experiencing PEM (e.g. having the problem at least half the time). However, the frequency and severity of PEM depend not only on severity of illness but also on a patient’s level of exertion. Most patients pace themselves very carefully to try to avoid PEM, and those who do would be appear not to have PEM and would be excluded from every NIH and CDC study.
The working group are aware of this problem and talk about having researchers ask supplemental questions (e.g. the effect if/when they engage in physical or mental activity and whether there are activities they avoid because it exacerbates symptoms). But surely the better approach would be to use a questionnaire that asks patients directly what happens if they exert themselves, in order to reveal whether they have PEM?
If other patients share my concerns, then we need a clear plan from the NIH/CDC to urgently develop a replacement questionnaire, based on input from patients.
So I’d appreciate any answers to these questions:
- Does the DSQ fall short of properly capturing post-exertional malaise?
- If so, should we be asking for a timetabled plan to urgently develop a better alternative?
IMPORTANT. This is not intended as a criticism of Professor Leonard Jason, who has been a lonely pioneer of case definitions and PEM in particular. Without his and his team’s research there would be nothing to use now, and we do need something in the interim. Nor is this a criticism of the working group (co-chaired by Lily Chu and patient-advocate Mary Dimmock). This group has produced many good recommendations and has highlighted many of the weaknesses of the DSQ.
This, though, is about how PEM will be defined in every NIH and CDC study, including every biomedical study, so it needs to be as good as it can be, as soon as possible, to produce the best possible research.
