Preprint Psychometric evaluation of The Index of Myalgic Encephalomyelitis Symptoms TIMES. Part II…, 2026, Tyson, Horton, Fleming

SNT Gatchaman

SNT Gatchaman

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Psychometric evaluation of The Index of Myalgic Encephalomyelitis Symptoms TIMES. Part II: Criterion-related and discriminant validity, test-retest reliability and minimal detectable difference.
Sarah F Tyson; Mike C Horton; Russell Fleming

OBJECTIVE
To evaluate the criterion-related and discriminant validity, test-retest reliability and minimal detectable difference of The Index of ME Symptoms (TIMES) in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

METHODS
People with ME/CFS in the UK completed the TIMES online (n=1055). Rasch-transformed interval data and parametric statistics were used: Pearson correlations (with the ME severity scale); analysis of variance; intra-class correlations (ICC) and standard error of measurement of ICC measured criterion-related and discriminant validity, test-retest reliability and minimal detectable difference respectively.

RESULTS
Highly significant (P<0.001) moderate (r=0.400- 0.528) correlations were seen between the TIMES scales and severity of ME/CFS except the gastro-intestinal and immune systems scales (r= 0.315 and 0.302 P<0.001 respectively). Discriminant validity was demonstrated with significant differences in TIMES scores between all five levels of ME severity, except between levels 4 and 5 in some cases, which were underpowered due to the small group numbers. Test-retest reliability was excellent (ICC>0.7, p<0.001) except the cranial nerves and immune system scales which were good (ICC = 0.681 and 0.669, p<0.001) and minimal detectable difference was excellent (3.95-17.45%).

CONCLUSIONS
The Index of ME Symptoms (TIMES) scales are valid, reliable, sensitive assessments of symptoms in ME/CFS. They are freely available for use.

Web | DOI | PDF | Preprint: MedRxiv | Open Access
 
The domains excluding fatigue also form valid sub-scales which assess neurological symptoms and dysautonomia.
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We commented in the thread for the first paper that it makes no sense to have cranial nerves in a dysautonomia section when neurology is right there. Also sleep and the immune system in dysautonomia ?!? (As well as dysautonomia relating to neurology anyway). Arbitrary and ill-informed.

The TIMES was co-produced with people with ME/CFS and clinicians working in specialist NHS ME/CFS services using the methods detailed in the companion paper. They are summarised here. An ME/CFS advisory group with a wide range of age, duration and severity of ME/CFS was convened from volunteers following publicity in the ME Association’s newsletter. Members of the clinical advisory group were drawn from volunteers from the membership of the British Association of Clinicians in ME (BACME). Both groups contributed to all stages of the project.
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TIMES.png
 
"Spoiler: Content warning for crimes against graphic design"
:) you've got to laugh....

I have no idea why they had to spread this stuff over two papers. It seems to be repeating a lot of what was in the first paper, which mostly seems to be 'this is great, we did a fabulous job'.

And I repeat - one question on PEM and, what was it five or six? on aspects of sleep. This is junk that will make it relatively easy for rehab people to show they have achieved improvements when in fact they have not. 'Excessive farting'* could go from 3 points to zero points just by telling the patient that the average person farts around 20 times a day, and 40 times is still regarded as normal. PEM could genuinely go from mild frequency to moderate frequency and it wouldn't increase the score at all.

This scale is junk.

*yes, I am not joking it is a symptom on the list


Here's the scale for easy access:
Supplementary file 4 is the TIMES final version. Attaching it here so that people can more easily acces it.
View attachment 30731
 
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