The pain relieving effects of acupuncture compared with placebo are small and seem to lack clinical relevance, according to a study published on bmj.com.
Researchers at the Nordic Cochrane Centre in Copenhagen analysed evidence from thirteen acupuncture pain trials involving over 3,000 patients. The trials compared three arms of treatment (real acupuncture, placebo or 'pretend' acupuncture or no acupuncture) for a broad range of common conditions such as knee osteoarthritis, migraine, low back pain and post-operative pain.
Before the analysis, differences in study design and quality were taken into account to minimise bias.
They found a small analgesic effect of real acupuncture compared to placebo acupuncture. This corresponded to a reduction in pain levels of about 4mm on a 100mm pain scoring scale. A 10mm reduction on this scale is classed as 'minimal' or 'little change' so the apparent analgesic effect of acupuncture seems to be below a clinically relevant pain improvement, say the authors.
They found a moderate difference between placebo acupuncture and no acupuncture (10mm on a 100mm pain scoring scale), but the effect of placebo acupuncture varied considerably. Some large trials reported effects of placebo that were of clear clinical relevance (24mm), whereas other large trials found effects that seemed clinically irrelevant (5mm).
The authors could not explain this variation, but they did not find an association between the type of placebo acupuncture and its effect.
Our findings correspond with several Cochrane reviews on acupuncture for various types of pain, which all concluded that there was no clear evidence of an analgesic effect of acupuncture, say the authors.