Differences in ME and CFS Symptomology in Patients with Normal and Abnormal Exercise Test Results

[Cheesus]

Stephanie L McManimen and Leonard A Jason

Int J Neurol Neurother, IJNN-4-066, (Volume 4, Issue 1), Research Article; ISSN: 2378-3001
Received: August 24, 2016 | Accepted: March 18, 2017 | Published: March 21, 2017

Abstract

Post-exertional malaise (PEM) is a cardinal symptom of myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS), which often distinguishes patients with this illness from healthy controls or individuals with exclusionary illnesses such as depression. However, occurrence rates for PEM fluctuate from subject to how the symptom is operationalized. One commonly utilized method is exercise testing, maximal or submaximal. Many patients with ME and CFS experience PEM after participating in these tests, and often show abnormal results. However, some patients still exhibit normal results after participating in the exercise testing. This study examined the differences between two patient groups with ME and CFS, those with normal results and those with abnormal results, on several PEM-related symptoms and illness characteristics. The results suggest those that displayed abnormal results following testing have more frequent and severe PEM, worse overall functioning, and are more likely to be bedbound than those that displayed normal results.

https://www.clinmedjournals.org/art...logy-and-neurotherapy-ijnn-4-066.php?jid=ijnn

 

[Diwi9]

This finding result in a heterogeneous patient population for research involving exercise testing, which may help explain the discrepant results found in previous studies. Additionally, since the group with abnormal exercise test results is more likely to be bedbound or housebound, it is possible that they are unable to make it to a tertiary clinic to participate in these research studies. As a result, the more severely impaired group patients with ME and CFS may be excluded from analyses comparing the full patient population to healthy control populations. This could prevent researchers from finding significant differences between patients and controls if the more impaired patients are unable to participate in research.

I respect Leonard Jason's persistence at applying logic to ME/CFS studies. He has been a ceaseless advocate for our community through his work.

 

[*GG*]

Abstract
Post-exertional malaise (PEM) is a cardinal symptom of myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS), which often distinguishes patients with this illness from healthy controls or individuals with exclusionary illnesses such as depression.

However, occurrence rates for PEM fluctuate from subject to how the symptom is operationalized. One commonly utilized method is exercise testing, maximal or submaximal.

Many patients with ME and CFS experience PEM after participating in these tests, and often show abnormal results. However, some patients still exhibit normal results after participating in the exercise testing.

This study examined the differences between two patient groups with ME and CFS, those with normal results and those with abnormal results, on several PEM-related symptoms and illness characteristics.

The results suggest those that displayed abnormal results following testing have more frequent and severe PEM, worse overall functioning, and are more likely to be bedbound than those that displayed normal results."

GG

 

[Dolphin]

I read this. Virtually all the data is in the tables.

 

[Dolphin]

For those that only had a one-day test, 45.0% (N = 63) had normal results and 55.0% (N = 77) had abnormal results. For the participants that had a two-day test, 8.6% (N = 3) had normal results and 91.4% (N = 32) had abnormal results

 

[Dolphin]

The abnormal results group had a significantly higher education level compared to the normal results group [χ2 (3) = 12.39, p < 0.01] so this was controlled for in subsequent analyses.

This seems a bit odd.

Here are possible explanations that I have come up with:
- people with higher education investigate their results more deeply either by their own analysis and/or asking about them meaning they were more inclined to notice differences.

- People with higher education are a different group from those who do not fit this category. For example, the diagnosis is more accurate in the higher educated group. This study depended on patients reporting their diagnosis rather than being screened specifically for this study.

-Possibly people with higher education who have ME/CFS are more able to work compared to those with a similar severity of illness because their jobs are less dependent on physically demanding activities. Perhaps this might mean the average highly educated person in the ME/CFS community is more severely affected than the average less educated person as perhaps if you were able to work especially full-time, you are less focused on what is happening in the ME/CFS community???

 

[Dolphin]

There isn't a huge amount of difference between the 2 groups so I am not too excited by this study:

 

[Dolphin]

To be extra critical, I wonder could believing you had normal or abnormal tests on an exercise test influence how you might answer questions on the effects of exercise i.e. if you had or believed you had a normal test, you might report the effects of exercise being less severe than if you had an abnormal test??

 

[Snow Leopard]

I think the education thing suggests there are participation biases in these studies.

I wonder could believing you had normal or abnormal tests on an exercise test influence how you might answer questions on the effects of exercise i.e. if you had or believed you had a normal test, you might report the effects of exercise being less severe than if you had an abnormal test?

I've done the 2 day CPET and well, it you actually achieved maximal exertion, you will feel it, regardless of whether you had a VO2 max in the normal range (I did) or not (thought the second day was still around 10% lower performance). I was feeling worse than usual for about 3 weeks.

Seriously, maximal exertion is really hard for a person with ME, it hurts for a long time. If you can achieve normal results and don't feel it much afterwards, you simply aren't very ill.

 

[Dolphin]

Only 20% (N = 35) of these participants were asked to exercise on back-to-back days.

 

[Dolphin]

I've done the 2 day CPET and well, it you actually achieved maximal exertion, you will feel it, regardless of whether you had a VO2 max in the normal range (I did) or not (thought the second day was still around 10% lower performance). I was feeling worse than usual for about 3 weeks.

Seriously, maximal exertion is really hard for a person with ME, it hurts for a long time. If you can achieve normal results and don't feel it much afterwards, you simply aren't very ill.

Only 20% of the people in the study had done a two-day test.

And the tests that were done were not necessarily maximal.

Also these questions weren't asked just after people did exercise tests. These were just general questions about how they responded to exertion, rather than after the exercise test specifically.

 

[Dolphin]

Just in case it is not clear: exercise tests were not run specifically for this study. People were just asked to report on any testing they may have had in the past.

 

[happy]

I think the reason why Normal Result and Abnormal Result groups look so similar is that one day exercise test tells us nothing anyway. Many patients who got a normal result on 1-day test would get abnormal result if doing 2-day test and were therefore wrongly categorized.

Isn't it interesting that only 3 out of 30+ patients who did two day CPET had "normal result"? Of course there could be other reasons (only more severe patients did two day CPET for example), but a normal result on 2 day CPET cannot be equated to normal result from one day CPET. I think it was a big mistake to combine both results.