Trial methodology and patient characteristics did not influence the size of placebo effects on pain (2008) Kamper et al

Objective
To determine whether trial-design, patient-type, or placebo-type factors influence the size of the placebo analgesic effect in clinical trials.

Study Design and Setting
Trials that measured pain outcomes in Hróbjartsson and Gøtzsche's meta-analysis were retrieved and coded for eight factors potentially predictive of placebo effect size. Random effects meta-regression was used to explore the predictive power of each factor on placebo effect size. The factors investigated aspects of trial design (nonstandardized co-analgesia, co-intervention), patients (pain type, patient group, residual pain score), and placebo (placebo type, indistinguishability, structural equivalence). The meta-analysis undertaken in the original study was also repeated to confirm the results.

Results
The pooled effect of placebo was 3.2 points on a 100-point scale (95% confidence interval [CI]=1.6–4.7). None of the selected factors influenced the size of placebo effect: the effect of all factors was close to zero, all CIs spanned 0, and P-values ranged from 0.13 to 0.90.

Conclusion
This study confirms the findings of previous researchers that, at present, the evidence for large placebo analgesic effects in clinical trials is lacking. Importantly, this analysis also establishes that larger placebo effects are not associated with particular aspects of the trial methodology, patient, or placebo type.

https://www.jclinepi.com/article/S0895-4356(07)00274-0/fulltext

 

3%, sounds about right, it easily falls into any reasonable confidence interval, given the inability to actually measure anything. So it's more of a real zero, adjusted upward for bias and feelings. Subjective ratings on a 1-10 scale have a minimum 10-20% imprecision to them, since it's impossible to be any confident that a 6 isn't actually closer to a 5 or a 7, just a middle ground compromise between ratings on what are usually relative scales.

3% compounded interest rates over a millennia can add up to a significant sum, or significant progress. 3% total effect is not even worth looking at, considering the margin of error here is larger than 3. And yet many papers and reviews somehow conclude far differently, with large effect sizes that confound everything. How odd.

Well, Wessely sure was right that this is the most powerful intervention they have, since they have nothing. At the expense of millions of lives, however, this is criminally insane. There's literally nothing here and there's a giant industry servicing this and the medical profession is more accepting of this than a Goop convention is accepting of scented candles.

Why is medicine so infinitely horny over this stuff? I'll never get it, so cringe-worthy. As a topic, it should be the target of far more challenge given that psychosomatic treatment models essentially abuse this imprecision. It's well past time this nonsense is put to rest, the last remaining professional belief system, responsible for the last acceptable form of bigotry, at least officially.