Perception of induced dyspnea in fibromyalgia and chronic fatigue syndrome (2018) Van Den Houte et al

https://www.ncbi.nlm.nih.gov/pubmed/29455899
http://www.jpsychores.com/article/S0022-3999(17)31032-2/fulltext

 

No it doesn't, because there is no data showing that the observed results are specific to "functional somatic syndromes".Where is the comparison to similar chronic disabling illnesses such as heart disease or multiple sclerosis?

Even if it were a specific finding, it would still be unclear what this means, even though the authors would probably jump to the conclusion that patients attention to their body is causing symptoms.

 

Full text is at https://sci-hub.tw/https://doi.org/10.1016/j.jpsychores.2018.01.007

These are Belgian quacks, primarily from Leuven.


So the real test is how long it takes patients to recover from breathing in an elevated amount of carbon dioxide, after they return to breathing normal air without being aware of the switch:

They're explicitly starting with the assumption that the patients are completely physically healthy:

Their hypothesis is that FM/CFS-crazy will look like medically unexplained dypsnea-crazy on this test:

Fukuda was used to recruit CFS patients, with exclusions based on "chronic cardiovascular, respiratory or neurological disorders" among other things. I'm not quite sure how you exclude patients with neurological disorders in a study involving a disease which is officially classified as neurological


This doesn't sound like standard practice, and it's not clear if patients and controls are being tested with the same equipment in a reasonable ratio with each other:

It sounds like they made a lot of comparisons without making statistical corrections for the increased likelihood of a false positive:

They lost a lot of data, primarily due to technical problems. The distribution of those losses suggests that patients and controls were not being tested with the same equipment:

What a mess. I guess this answers the question of what happens when you exclude neurological disorders from a study of a neurological disease. And what was the point of the diagnostic questionnaires if they were going to be ignored? Presumably they needed the results from those "patients" to get their desired conclusion:

This is a pretty shitty p-value, especially since this group didn't correct for making multiple comparisons and has done these sorts of studies before with other groups, and should be able to focus on the essential outcomes by now. It's likely a false positive, and even if it weren't it would only indicate that FM/CFS patients take longer to recover - it would not rule out a physical cause:

Again, a shitty p-value. And even that is only correlated with physical symptoms, and not with mood or psychiatric disorder. Even most psychosomatic questionnaires would only consider symptoms to be psychosomatic if there is also a mood disorder, hence the lack of association between the results and the mood/psychiatric symptoms seems to disprove their hypothesis:

 

Thanks @Valentijn for saving me the effort of trying to understand it.

Have I got this right? On the basis of a very brief test on a small sample of patients that showed a barely significant difference in perception of breathlessness between FM/CFS patients and healthy controls, they extrapolate to say this is evidence that patients with all so called functional syndromes have altered symptom perception for all symptoms? That is the most outrageous extrapolation.

 

Yes, exactly. It's also combined with some severe methodological problems which make it very unlikely that there was any statistical significance at all.