Objective cognitive performance and subjective complaints in patients with chronic Q fever or Q fever fatigue syndrome: Reukers et al June 2020

[Sly Saint]

Abstract
Background

Primary aim of this study was to compare cognitive performance of patients with chronic Q fever or Q fever fatigue syndrome (QFS) to matched controls from the general population, while taking performance validity into account. Second, we investigated whether objective cognitive performance was related to subjective cognitive complaints or psychological wellbeing.

Methods
Cognitive functioning was assessed with a neuropsychological test battery measuring the domains of processing speed, episodic memory, working memory and executive functioning. Tests for performance validity and premorbid intelligence were also included. Validated questionnaires were administered to assess self-reported fatigue, depressive symptoms and cognitive complaints.

Results
In total, 30 patients with chronic Q fever, 32 with QFS and 35 controls were included. A high percentage of chronic Q fever patients showed poor performance validity (38%) compared to controls (14%, p = 0.066). After exclusion of participants showing poor performance validity, no significant differences between patients and controls were found in the cognitive domains. QFS patients reported a high level of cognitive complaints compared to controls (41.2 vs 30.4, p = 0.023). Cognitive complaints were not significantly related to cognitive performance in any of the domains for this patient group.

Conclusions
The high level of self-reported cognitive complaints in QFS patients does not indicate cognitive impairment. A large proportion of the chronic Q fever patients showed suboptimal mental effort during neuropsychological assessment. More research into the underlying explanations is needed. Our findings stress the importance of assessing cognitive functioning by neuropsychological examination including performance validity, rather than only measuring subjective cognitive complaints.

https://bmcinfectdis.biomedcentral.com/articles/10.1186/s12879-020-05118-z

 

[Trish]

I have only read the abstract. What is 'performance validity'. And does the conclusion 'suboptimal mental effort' mean they are blaming the patients for lack of effort?

 

[Peter T]

I have only read the abstract. What is 'performance validity'. And does the conclusion 'suboptimal mental effort' mean they are blaming the patients for lack of effort?

It would seem to me that this ‘phenomenon’, though it is not quite clear what the authors have observed, could in itself represent a cognitive impairment.

Given high levels of variation between individuals within the normal population surely you would need considerably larger groups sizes to make meaningful comparisons between the groups, it would be wonderful indeed if the 30 patients and 35 controls just happened to equally reflect the same bit of the entire populations normal distribution. The fact that they found no differences between their groups Is for me worrying, and raises the question are their tests sensitive enough.

I would have thought that either you need studies comparing pre and post morbid performance, which is generally impossible or much larger sample sizes.

 

[rvallee]

This is frankly supposed to be easy stuff, I don't know how someone can screw it up but, BPS I guess, it's the sticker that tells you something is useless. Researchers with no personal insight into brain fog will never select the appropriate tests. And even then you need to go through a systemic process.

This makes me think of a common problem in software engineering: testing. Programmers can only test for problems they can think of, the ones they considered enough to code for. That's why there is an entirely separate discipline of quality assurance, which goes through all the imaginable and unimaginable tests possible, including random dumb stuff that no one would think about but where most of the bugs are actually found. QA is skipped entirely in some places. With disastrous consequences. BPS is just like that, coding without thought to begin with and no QA to verify anything.

If you don't know what you are actually testing you will not do the appropriate tests. Supply-side medicine strikes again, physicians thinking about physician things among physicians, validated by physicians and for physician needs. You can't keep on just searching where the light shines. If you are doing research you are expected to go where it's dark.

Really obvious that the entirety of the BPS model serves no purpose whatsoever because the people involved in it can't do the basic things they need to do while believing they are totally nailing it, like some drunk blaring out at the microphone while the crowd boos and asks them to leave but they're too drunk to even be aware of a crowd of booing angry people.

 

[Hoopoe]

This smells like garbage.

There is no chance my cognitive problems are due to lack of effort and I highly doubt it's any different with other patients and similar illnesses.

 

[wigglethemouse]

Awful. I don't know why I clicked on this thread. Lets just disbelieve the patients rather than try and understand why the tests are not capturing the cognitive decline patients are complaining about.

Our study had some limitations.

That's pretty clear. Huge age difference between groups to start with but sample sizes too small for your correction formulas to be of use

Due to the high number of chronic Q fever patients with poor performance validity, the analysis could only be performed in a valid sample of 18 chronic Q fever patients.

Ummmmm, why aren't you focusing on this key finding instead of chucking 38% of patients out of this group so you can get a null result.

This is below the number that was necessary according to the sample size calculation and may have been insufficient to detect relevant effect sizes.

Duh.

However, it should be stressed that taking performance validity into account is a strength of our study design.

Uhhhhh nope. Seems more like fiddling with the results to me.

 

[rvallee]

I am bothered by this term and need to know more:

Performance validity was assessed using the short form of the Amsterdam Short-Term Memory Test (ASTMT) [25,26,27]. A score lower than 82 was used as a cut-off for suboptimal effort [28], with a specificity of 97% and a sensitivity of 65%.

From another source because those tests are always proprietary and hidden from public view, but somehow many sources describe it as a malingering test and I have no idea how that even works:

The Amsterdam Short-Term Memory Test (ASTM; Schmand & Lindeboom, 2004) is a 30-trial word recognition test. Each trial consists of five words from a particular semantic category (e.g., five vegetables), which participants are instructed to read aloud and to memorize. Subsequently, the participant has to solve a relatively simple addition or subtraction problem. Finally, participants have to select three out of five words (containing two semantically related foils) that they recognize from the first list.

How does poor performance on that test invalidate other tests to the point of warranting exclusion from analysis? It's not an especially good test but there is no possible reason to do that arbitrary exclusion. Unlike things about mood and beliefs it's a test that has some relevance, it actually tests performance, which is the point.

What a complete mess. As usual the deeper you look the worse it gets.

Also:

Premorbid IQ was estimated with the Dutch version of the National Adult Reading Test (NART-IQ)

How is that valid?

There are several possible explanations for the high number of chronic Q fever patients with poor performance validity, but we were unable to confirm these hypotheses in this study. First, depressive symptoms could have affected test behavior.

If it's valid to posit that the test can be influenced by unrelated factors than by definition it is either a poor test, was incorrectly used or it's simply a BS excuse for disappointing results.

The ‘Q fever claim’ that was ongoing during the data collection phase of this study should also be taken into account. A collective of 300 Q fever patients had started a lawsuit for compensation from the Dutch government for neglecting to inform the public about the dangers of Q fever and not taking adequate measures to protect the public from these dangers

I see that excuse is now being re-used. This is absolutely laughable, not for the authors but for the journal. BMJ, where requirements are optional, peer review is a rubber stamp and substance does not matter as long as you label it BPS.

 

[Hutan]

Just wanted to make it clear that there are two patient groups, one with QFS (that is, essentially CFS) and one with chronic Q fever. I presume the chronic Q fever group still has evidence of an ongoing infection, but I haven't seen the full paper.

It's only the chronic Q fever group that is accused of suboptimal effort.

A very small percentage of people (less than 5 out of 100) who become infected with C. burnetii bacteria develop a more serious infection called chronic Q fever. Chronic Q fever develops months or years following initial Q fever infection. People with chronic Q fever often develop an infection of one or more heart valves (called endocarditis). People with endocarditis may experience night sweats, fatigue, shortness of breath, weight loss, or swelling of their limbs. A healthcare provider will need to perform a series of tests to diagnose endocarditis.

Chronic Q fever is serious and can be deadly if not treated correctly. Chronic Q fever infection requires months of antibiotic treatment. Chronic Q fever is more likely to occur in people with heart valve disease, blood vessel abnormalities, or in people with weakened immune systems. Women infected during pregnancy may also be at risk for developing chronic Q fever.

It seems to me a lot more likely that the reduced ability of many in this group on the test that was arbitrarily used to decide if someone was trying hard enough, is due to having an ongoing infection, possibly with endocarditis.

But yeah, just wanted to point out that the QFS group wasn't found to be not trying hard enough. They were however found to be doing well enough for it to be suggested that there was 'no cognitive impairment'.

Researchers with no personal insight into brain fog will never select the appropriate tests.

This. The fact that someone seemed ok on a specific, possibly irrelevant test at a specific time for a specific (short) duration of testing doesn't mean that there is no problem.

 

[Snow Leopard]

Only patients with significantly above average cognitive ability are usually willing to participate in studies like this in the first place. The study didn't prospectively study these participants from before they became ill, hence the study is only of "suggestive" quality evidence.