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Acupuncture for Knee Pain

Posted by medconsumers on August 1, 2007

Strong Placebo Effect

How good is acupuncture at alleviating the pain of knee osteoarthritis? Studies have attempted to answer this question, but results are mixed. One solution is an analysis of all the highest quality trials on the topic. The results, published recently in Annals of Internal Medicine, say more about the power of the placebo than any substantial painkilling effect of acupuncture and may be disappointing to anyone looking for a safe alternative to drugs.

The new analysis was conducted by Eric Manheimer, University of Maryland School of Medicine, Baltimore, and colleagues at two European medical centers. They found nine trials had produced enough information to pool results and came to a conclusion about the effectiveness of acupuncture for arthritic knee pain.

All nine trials had some sort of comparison group against which the effects of acupuncture could be measured. The comparator was either a sham procedure (i.e., needles placed away from the traditional acupuncture points), or usual care (e.g., education and anti-inflammatory drugs), or time spent on a waiting list for acupuncture treatment. All trials had randomly assigned participants to receive one of these treatments or acupuncture for at least six weeks. The phrase randomly assigned means that the participants cannot choose their treatment.

Acupuncture showed moderate to large benefits in the trials that compared it with usual care or waiting list, and small benefits in the trials that compared it with a sham procedure. Yet acupuncture showed little to no benefit in the two trials that compared it with a sham acupuncture procedure that was clearly indistinguishable to the participants from the true acupuncture. The analysis of all nine trials suggested that the more likely participants knew or suspected they were getting real acupuncture, the more likely they were to report a benefit. This led Manheimer and colleagues to conclude that placebo effects are perhaps mostly responsible for the benefits of acupuncture. In a telephone interview, Eric Manheimer mentioned the importance of trials that not only had sham acupuncture as a comparator but had also tested the credibility of the sham procedure. This means that after the trial is over, the investigators asked the participants if they knew whether they were getting the real or the sham acupuncture, explained Manheimer, and they could not distinguish between the two procedures.

But things are even more complicated because the sham acupuncture can involve intensive needling, Manheimer continued, “and this insertion of needles, even if they are not in the right place and even if it’s just superficial, may have some physiological or biological effects.” He suspects that this could partly explain why there was no difference between the effect of sham and real acupuncture in the combined results of the two trials that used a particularly intensive version of fake needling.

Despite the finding that much of the benefit of acupuncture appears to be due to patients’ expectations, the researchers were not closing the door on it. Manheimer and colleagues concluded that acupuncture “seems to have a genuine biological effect suggested by the small short-term improvements in pain and function shown in the trials compared with sham.” In addition, no adverse effects were reported in the trials, which is more than can be said about arthritis drugs.

“Like acupuncture, many prescription painkillers have benefits that are also probably too small to be meaningful to patients,” said Manheimer. “Given the limited treatment options available for patients with arthritis and the possibility of a slight short-term benefit of acupuncture, some might consider acupuncture as one treatment option in a multidisciplinary approach to treating knee osteoarthritis.”

Maryann Napoli, Center for Medical Consumers ©
August 2007

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