The findings, published in the September issue of the journal Arthritis Care and Research, are the latest to suggest that a powerful but little understood placebo effect may be at work when patients report benefits from acupuncture treatment, which involves inserting thin needles deeply into the skin at specific points on the body.
The study, from the M. D. Anderson Cancer Center, tracked 455 patients with painful knee arthritis who received either traditional Chinese acupuncture or a sham treatment. A control group of patients was put on a waiting list for acupuncture treatment. Patients were told only that the study was comparing a traditional versus nontraditional form of acupuncture.
In the real treatment group, needles were inserted at specific points on the body and manipulated in accordance with traditional Chinese acupuncture techniques. In the sham treatment group, needles also were inserted, but not at the locations traditionally used for acupuncture. Electrical stimulation was also used, although those in the sham group received lower voltage and far shorter treatments.
Compared to people on the waiting list for treatment, both the real and sham acupuncture groups had statistically significant reductions in pain, averaging about a one point drop in pain on a scale of 1 to 7. The researchers also found that the enthusiasm of the person inserting the needles had a small but statistically significant effect. Patients reported slightly more pain relief when they were treated by someone who said "I've had a lot of success with treating knee pain," compared with a practitioner who took a more neutral stance, saying "It may or may not work for you."
The results don't mean acupuncture doesn't work, but they do suggest that the benefits of both real and fake acupuncture may have something to do with the way the body transmits or processes pain signals. Other studies have suggested that the prick of a needle around the area of injury or pain could create a "super-placebo" effect that alters the way the brain perceives and responds to pain.
The study design may also have blurred the lines between real and fake acupuncture, muting the effects of the real thing. For instance, in traditional Chinese acupuncture, the needle insertion points are along specific areas called meridians, but the exact point of insertion is decided on a patient-by-patient basis, depending on the patient's body and area of pain. In the study, however, a standard map was used so that the needle insertion point was the same for every patient. In addition, trained acupuncturists also were asked to administer the fake treatment and insert needles at specific points outside of traditional meridians. Although researchers sometimes stepped into treatment sessions to check on the location of the needles, it's possible that some of the sham treatments were similar to real acupuncture.
The current findings are similar to a 2007 study of 1,200 patients with back pain who were also given real acupuncture, a sham treatment or traditional back care such as physical therapy or exercise treatment. In that study about half the patients in both the real and fake acupuncture groups reported significant pain relief compared to only 27 percent of those receiving traditional back care. In that study, however, real acupuncture did reduce the need for pain medicine. Only 15 percent of patients who received real acupuncture used extra pain medication, but 34 percent of patients in the sham group and 59 percent of patients in conventional therapy needed extra pain pills.
A 2007 National Health Interview Survey found that an estimated 3.1 million Americans had used acupuncture in the past year. Back pain is the most common reason patients seek acupuncture treatment, followed by joint pain, neck pain, migraines and other forms of recurring pain.
The National Center for Complementary and Alternative Medicine offers an extensive review of the research on acupuncture, including studies of acupuncture for back pain, knee arthritis, post traumatic stress, fibromyalgia and fertility treatment.