Activity measurement in pediatric chronic fatigue syndrome, 2020, Jason et al

From Leonard Jason's group.

I find this separation a bit odd - I don't think there's enough evidence to differentiate two conditions.

. It's not clear if people who met the requirement for both CFS and ME are included in this study.

35 children who met the Fukuda criteria and 15 healthy controls.

Some bias in the samples I think:
Patients: Male 42.9%; Female 57.1%
Controls: Male 60%; Female 40%
I know there's lots of variation, but I think in most Western cultures, female 13 year olds tend to be less active than males.

Also the time of the year worn:
Patients: During the school term 45.7%; school holiday 54.2%
Controls During the school term 33.3%; school holiday 66.7%
The controls were wearing the activity monitor for much more time in the holidays compared to the patients. Normal patterns of activity during school and holidays are different.

 

Certainly that's what I would expect. But I'm not sure that Figure 1 really shows a lot of night-time activity. Neither group is doing much between 10 pm and 6 am.



The activity monitor was only worn for one day by each participant. This is acknowledged as a limitation by the authors - behaviour might easily change for a day when the participant knows their activity is being analysed. This could easily be a reason why the activity and fatigue levels didn't correlate.

I don't think this finding can be extrapolated beyond this study. Here, the participants had no particular incentive or pressure to report a particular level of activity. That will probably not be the case with most unblinded intervention studies. This paper should not be used to justify self-reporting of activity levels in such studies. If you are going to spend a lot doing a study, spend a bit more to do it properly by using activity monitors (and use them for a lot longer than a day).

 

They were worn around the waist.

Yeah, it isn't clear from the text if the selection was only of children who met the Fukuda definition but not a definition that they equate with ME. (Fukuda compliance but not CCC compliance) or (Fukuda compliance but not IOM compliance) is potentially quite different to (Fukuda compliance but not excluding those who also met more demanding criteria).

I suspect, given the effort the researchers went to to diagnose against various criteria and apply different labels of CFS and ME, the cohort is (Fukuda compliance but not compliance with a criteria that requires PEM). But the way the Fukuda criteria works, some of the cohort still might have had PEM.

It's not clear. It seems as though they are making their research less useful by trying to work within the confines of a criteria that doesn't mean much. I don't understand why good researchers still use Fukuda.

 

Sure, but why would an experienced ME/CFS researcher who understands the consequences of the various criteria use a potentially mixed cohort? Some of the Fukuda sample may not have PEM.