This is actually an interesting trial. It's one of the few that tested the effects of blinding and probably the only one that tested this in patients with CFS.
It's also a very large study. 409 CFS patients were randomized into four groups:
- Those who were blinded and received the intervention (distant healing)
- Those who weren't blinded and received the intervention (distant healing)
- Those who were blinded and were put on the waiting list control.
- Those who weren't blinded and were put on the waiting list control.
So there were approximately 100 patients in each group. The main outcome was the mental health component summary of the Sf-36 and that didn't show anything. But the secondary outcome the physical health component summary (PHCS), showed something interesting results.
View attachment 8464
The first three groups showed some small improvements, but the group that knew they were not being treated didn't improve. Although the difference was very small, the authors reported that it was significant (a result of their large sample size?).
So this seems to constitute evidence that the expectation of (possibly) receiving the intervention is sufficient to create a significant difference in reported physical health in a proper randomized trial, even if the intervention is something implausible as distant healing.
This was supported by a post-hoc analysis. The authors had asked the blinded patient groups whether they thought they were in the intervention or waiting-list control group. The mere belief of being in the intervention group caused a significant change in how patients reported their physical health:
The authors wrote that they "consider an effect size of d = 0.20 as clinically relevant."
So it seems that in an unblinded trial, expectations of possibly receiving the intervention suffice to create changes in reported physical health that look like clinically relevant effects, but disappear when patients are properly blinded.
Interested in hearing your thoughts on this trial
@Jonathan Edwards @strategist @Snow Leopard @Esther12 and others