Measuring improvement and deterioration in ME/CFS (2020) Kirke

Just noticed that this letter on measuring improvement and deterioration with the Chalder Fatigue questionnaire is now Open Access:

https://journals.sagepub.com/doi/full/10.1177/0141076820977843

 

Thanks Trish. I remember doing it through thick brain fog. I had to check and double-check and triple-check and quadruple-check all the "increase"s and "decrease"s to make sure I had the directionality right.

Maybe this is a brain-friendlier way of expressing it:

In a study at a centre where people did CBT for ME/CFS, the researchers said that people whose Chalder Fatigue scores went down by 2 points had improved, and people whose scores went up by 2 points had deteriorated.

Another study at 11 centres where people did various therapies for ME/CFS looked at what happened to people's Chalder Fatigue scores when they said they had gotten better or worse.

We would expect Chalder Fatigue scores to go down when people improve, showing that they have less fatigue

• But people whose scores went down by 2 points actually said that either their condition had not changed or was worse
• And people who said they were much better had scores that went down by quite a lot: about 11 points on a 33-point scale
• So if someone's Chalder Fatigue score goes down, we cannot tell whether they got better or got worse. We can only tell they've improved when their score goes down by a lot.

We would expect Chalder Fatigue score to go up when people get worse, showing that they have more fatigue

• But people who said they were worse often had scores that went down
• Some who said they were worse had scores that went up, but only by a small amount, for example 2 points
• So if we say that only people whose scores go up are getting worse, we will miss a lot of people who are getting worse.

This suggests that comparing Chalder Fatigue scores at the beginning of therapy and at the end of therapy might not be a good way of telling whether people with ME/CFS have improved or deteriorated. The change in these scores might make it look like there's more improvement than there really is, and less deterioration than there really is.