Validation of the PHQ-9 in adults with dissociative seizures, 2021, Lopez, Chalder et al

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Abstract
Background
The PHQ-9 is a self-administered depression screening instrument. Little is known about its utility and accuracy in detecting depression in adults with dissociative seizures (DS).

Objectives
Using the Mini – International Neuropsychiatric Interview as a reference, we evaluated the diagnostic accuracy of the PHQ-9 in adults with DS, examined its convergent and discriminant validity and uniformity.

Methods
Our sample comprised 368 people with DS who completed the pre-randomisation assessment of the CODES trial. The uniformity of the PHQ-9 was determined using factor analysis for categorical data. Optimal cut-offs were determined using the area under the curve (AUC), Youden Index, and diagnostic odds ratio (DOR). Convergent and discriminant validity were assessed against pre-randomisation measures.

Results
Internal consistency of the PHQ-9 was high (α = 0.87). While the diagnostic odds ratio suggested that a cut-off of ≥10 had the best predictive performance (DOR = 14.7), specificity at this cut off was only 0.49. AUC (0.74) and Youden Index (0.48) suggested a ≥ 13 cut-off would yield an optimal sensitivity (0.81) and specificity (0.67) balance. However, a cut-off score of ≥20 would be required to match specificity resulting from a cut-off of ≥13 in other medical conditions. We found good convergent and discriminant validity and one main factor for the PHQ-9.

Conclusions
In terms of internal consistency and structure, our findings were consistent with previous validation studies but indicated that a higher cut-off would be required to identify DS patients with depression with similar specificity achieved with PHQ-9 screening in different clinical and non-clinical populations."
https://www.sciencedirect.com/science/article/pii/S002239992100132X

 

(Is it wrong that I cringe when I see the name Chalder on an article? Even seeing the last name only....)

 

Those questionnaires assume a healthy person with no ongoing health limitations because they make no distinction of "can you do X" and "do you want to do X". It is invalid to use them this way and, no, personal conviction that there is "nothing wrong" with those patients does not allow an arbitrary exemption.

To put this in a different paper from the CODES paper looks a lot like using quantity over quality, just like PACE did hiding the bad news when they all could have fit in a single paper.

This is just lying with statistics, nothing more. It serves absolutely no purpose other than manufacturing junk evidence by quantity.

 

It's funny how these "validation" studies never actually bother to ask the patients themselves as to whether they think it is relevant, reflective of their experience or for that matter, do the questions make sense?

 

Ironically EC has recently made a big deal of asking patients about scales, illness perception / experience .

Sadly the power asymmetry is not recognised and language is so easily suggestible when conducting interviews .

AfME have said that children use different language to describe their illness without realising the mechanism by which children assimilate language .
Children use the language they are taught/ given until the construct dosnt hold true from experience .

EC and clinics are very good at providing language . The very act of ticking symptom boxes ( seemingly fatigue us more of an issue in paediatrics- I wonder why) sets up how things are described by providing defined variables .
When kids go " off piste" with their descriptions of experiences they are simply not listened to / disbelieved.