PHILADELPHIA — Acupuncture proved no more effective than sham treatments for treating pain from a common chronic condition, according to a new study.

For 12 weeks, researchers tested conventional acupuncture against treatments in which needles were improperly applied in 100 Seattle-area patients suffering from fibromyalgia, which is characterized by chronic pain in the head and torso.

The study concluded that adding acupuncture to other treatments the patients were already using provided no greater pain relief than sham acupuncture treatments, according to the Tuesday issue of Annals of Internal Medicine.

"We did not find that acupuncture reduced pain in patients with fibromyalgia," the study concluded.

Researcher Dr. Dedra Buchwald said the results were a surprise, given stories and testimonials from fibromyalgia patients who say acupuncture helps.

"We've seen it ourselves in our patients, that they swear by it they have a lot of faith that acupuncture works," she said.

In the study, patients in all the groups improved, but very early, after only one or two treatments — far earlier than most acupuncturists would expect an improvement — and then remained at the same level for the rest of the study, Buchwald said.

The results could mean that any form of acupuncture results in some form of improvement or that simply enrolling in the study and being hopeful about the outcome spurred an initial improvement in patients, she said.

The sham treatments — acupuncture for an unrelated condition, needle insertion at points that are not used in acupuncture, and simulated acupuncture that didn't actually pierce the skin — were intended to help pinpoint what elements of acupuncture might be beneficial.

"No one really knows what the active component of acupuncture is," Buchwald said.

She added that the questions researchers were asking were whether acupuncture is beneficial in treating fibromyalgia, and if so, what part of the treatment might be beneficial.

Buchwald cautioned that acupuncturists generally tailor treatment for each patient and often combine it with other forms of treatment, which cannot be done in a clinical trial.

Acupuncture, she said, "certainly works in acute pain control and it works in some conditions of chronic pain, so I don't think this is to say that acupuncture doesn't work at all."

Adam Burke, an acupuncturist who treats patients with fibromyalgia and was not connected with the study, said the findings were not conclusive, nor was the treatment the study's subjects received consistent with real-life alternative therapies for the condition.

Typically, such treatment can consist of more than a year of acupuncture, along with complementary therapies like herbs and lifestyle changes, he said. Also, acupuncture involving electrical stimulation that has been effective for fibromyalgia wasn't looked at in the study, said Burke, an assistant professor of health education at San Francisco State University.

Fibromyalgia is the second most-common rheumatologic condition after osteoarthritis and affects 2 to 4 percent of the U.S. population. Patients suffer chronic and widespread pain and sensitivity to pressure at various points on the body.

The cause of the condition is unknown, there are no laboratory tests for it and no treatments have proven effective, the researchers said.