This blog was first published on 15th March 2016 on BMJ Blogs (link no longer available).
Comments on: Ee et al Ann Int Med 2016
A large rigorous trial published in a prestigious general medical journal, and the usual mantra rings out – acupuncture is no better than sham. In this case there was not a fraction of difference from a non-penetrating sham in a two-armed trial with over 300 women. Ok, so we have known for some time that we really need 400 in each arm to demonstrate the usual difference over sham seen in meta-analysis in pain conditions, but there really was not even a sniff of a difference here. So is that it for acupuncture in hot flushes? Well, we have a 40% symptom reduction in both groups, and a strong conviction from some practitioners that it really seems to work. Is 40% enough for a strong conviction? I have heard some dramatic stories from medical acupuncturist colleagues that really would be hard to dismiss as non-specific effects, and from others I have heard relative ambivalence about the effects in hot flushes.
Personally, I always try to consider mechanisms, and I wish researchers in the field would do the same before embarking on their trials. That is not intended as a criticism of this trial, but some consideration of mechanisms might allow us to explain all our data, including the contribution of this trial.
Acupuncture has recognised effects that are local to the needle, in the spinal cord (mainly in the segments stimulated) and in the brain (as well as humoral effects in CSF and blood). The latter are probably the mildest of the three categories, and require the best group of patient responders for them to be observable in clinical practice.
Menopausal hot flushes are explained by the effects of reduced oestrogens on the thermoregulatory centre in the anterior hypothalamus. It is certainly plausible that the neuro-inhibitory effects of endogenous opioids such as beta-endorphin, which we know can be released by acupuncture stimulation in experimental settings, could stabilise neurones in the anterior hypothalamus that have become irritable due to a sudden drop in oestrogens.
So, are endogenous opioids always released by acupuncture? Well, they and their effects seem to be measurable in experiments that use what I call proper acupuncture. That is, strong stimulation to deep somatic tissue. In the laboratory, and indeed in the clinic, this is only usually achieved in a palatable manner by electroacupuncture to muscle, although repeated manual stimulation every few minutes may have similar effects.
Ee et al used a relatively gentle acupuncture protocol, so they may have only generated measurable effects, based on mechanistic speculation, in the most responsive patients, perhaps less than 10%.
What does all this tell us? Well, this trial clearly demonstrates that gentle acupuncture protocols generate effects in women with hot flushes via context rather than penetrating needling. In conditions that rely on central effects, I think we still need to consider stronger stimulation protocols and enriched enrolment in trials, ie preselecting responders before randomisation.
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