Acupuncture Has Minimal Analgesic Effect Over Sham Acupuncture

Better Understanding of Effects of Sham Acupuncture Needed

Marlene Busko

February 23, 2009

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February 23, 2009 — Pain relief with acupuncture is only slightly better than that achieved with sham, or "placebo," acupuncture, new research suggests. However, an accompanying editorial says that a better understanding of the effect of sham acupuncture may be the key to grasping the true analgesic effect of traditional acupuncture.

A large, systematic review of 13 three-group studies conducted by investigators at the Nordic Cochrane Center, in Copenhagen, Denmark, showed on a 100-mm visual analog pain scale that the effect of placebo acupuncture corresponded to a 10-mm reduction in pain, while true acupuncture added a further 4-mm reduction.

"We interpret this to mean that the analgesic effect of acupuncture is, to a very large degree, a placebo effect," review author Asbjorn Hrobjartsson, MD, told Medscape Psychiatry.

"The effect of true acupuncture seems to be too small to be of clinical relevance and is difficult to distinguish from bias due to incomplete blinding. The effect of placebo acupuncture seems, at times, to be quite effective," he said.

The study, which looked at acupuncture treatment for clinical conditions ranging from migraine to osteoarthritis to fibromyalgia, was published online January 27 in BMJ.

Parsing Out Placebo Effect

The theory of how acupuncture works is based on the existence of the vital energy Qi and meridians in the body, and acupuncture is commonly believed to have an important effect on pain, the authors write.

However, previous reviews of the analgesic effects of acupuncture vs placebo acupuncture vs no acupuncture or no treatment have reported conflicting results.

To analyze the effect of acupuncture and placebo acupuncture for pain, the researchers reviewed 13 clinical trials of acupuncture that randomized 3025 patients to 3 groups: true acupuncture, placebo acupuncture, or no acupuncture.

The review included trials of traditional acupuncture and electroacupuncture. Placebo acupuncture was done by superficial needling at nontraditional points in 7 trials, by other penetrative needling in 4 trials, and without skin penetration in 2 trials.

The patients were being treated for pain associated with colonoscopy (1 trial), fibromyalgia (1), low back pain (3), migraine (1), osteoarthritis (3), postoperative pain (2), scar pain (1), and tension headache (1).

All patients received standard care, usually analgesics (13 trials) or physiotherapy (5 trials). Thus, the findings are limited to the additive effect of acupuncture and placebo acupuncture.

There was a small difference in pain reduction with acupuncture vs placebo acupuncture and a moderate difference between placebo acupuncture and no acupuncture.

Since a consensus report characterized a 10-mm reduction on a 100-mm visual analog scale as representing "minimal" change or "little change," the findings in this review suggest that the analgesic effect of acupuncture on pain is not sufficient to be clinically relevant, the authors write.

Incomplete blinding of the patients, or the interaction between the patients and the acupuncturists, might explain some or even all of the observed effect, they note.

Not a True Placebo

In an accompanying editorial, Adrian White, MD, from the Universities of Exeter and Plymouth, in Plymouth, the United Kingdom, and Mike Cummings, MD, from the Royal London Homeopathic Hospital, in London, the United Kingdom, suggest that the small but significant difference between needling at classic anatomical locations and sham acupuncture may be due to the physiological difference between 2 active treatments — needling classic points in deeper tissues and incorrect points in more superficial tissues.

"Acupuncture 'placebo' generally involves placing needles in the wrong locations and is therefore likely to have some activity — in other words, this is not a true placebo," Dr. White told Medscape Psychiatry.

Commenting on the 10-mm reduction on the visual analog scale with placebo acupuncture and the further 4-mm reduction with acupuncture, he said: "Don’t forget the patient: the patient gains the total effect, in this case a 14-mm reduction, which is certainly worthwhile."

Needles as a placebo have a greater effect than placebo pills, for some reason that is not fully understood, he added.

The review was designed to search for trials with a similar methodology as opposed to similar clinical condition, which is an "unusual" approach. Therefore, because the analysis covers such a broad range of conditions, "it cannot directly inform clinical decisions about patients with particular conditions," the editorialists note.

Nevertheless, they add, "the overall effect size of acupuncture in relation to usual care may be clinically relevant for musculoskeletal conditions, particularly in view of the limited treatment options and acupuncture’s safety record and patient preference.

"Conventional systematic reviews of acupuncture’s effect on specific conditions provide evidence for an effect in nausea, chronic back pain, knee osteoarthritis, postoperative pain, and tension headache," said Dr. White. "Other reviews are suggestive but not conclusive for an effect in other conditions, and still others suggest no effect on smoking cessation or for stroke recovery," he said.

The review authors report no financial disclosures. The editorialists, Dr. White and Dr. Cummings, are employees of the British Medical Acupuncture Society, a registered charity established to encourage the use and scientific understanding of acupuncture within medicine for the public benefit. Dr. White is editor in chief of Acupuncture in Medicine.

BMJ. Published online January 27, 2009. Abstract Abstract

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