CHICAGO (Reuters) - Acupuncture brought more relief to people with back pain than standard treatments, whether it was done with a toothpick or a real needle, U.S. researchers said on Monday in a study that raises new questions about how acupuncture works.

A woman receives facial acupuncture at the Beautyworld Japan trade fair in Tokyo May 20, 2008. REUTERS/Yuriko Nakao

For many patients, that benefit lasted for a year, the team reported in the Archives of Internal Medicine.

“Our study shows that you don’t need to stick needles into people to get the same effect,” said Dr. Daniel Cherkin of Group Health Center for Health Studies in Seattle, who led the study.

“Historically, some types of acupuncture have used non-penetrating needles. Such treatments may involve physiological effects that make a clinical difference,” Karen Sherman of Group Health, who worked on the study, said in a statement.

The team, wanted to study the effects of different types of acupuncture in a large, carefully controlled study of 638 patients with chronic low back pain.

They divided patients into several groups. One got seven weeks of standardized acupuncture treatment known to be effective in back pain. Another group got an individually prescribed acupuncture treatment.

A third group was treated using a toothpick in a needle guide tube that did not pierce the skin as regular acupuncture does, but targeting the correct acupuncture “points”.

A fourth group just got standard medical treatment, which included medication and physical therapy.

After eight weeks, 60 percent of the patients who got any type of acupuncture reported significant improvement in their ability to function compared with those who got standard medical care alone.

But there was no significant difference in the pain relief people got from the acupuncture using needles or from toothpicks.

The researchers said there is some evidence that even needles were used 2,000 years ago in acupuncture treatment, and some imaging studies have shown that “superficial and deep needling of an acupuncture point elicited similar blood oxygen level-dependent responses,” the team wrote.

Another study even found that lightly touching the skin can induce some emotional and hormonal reactions, which could explain the benefit, they wrote.

Or, it may simply be the experience of visiting an acupuncturist for treatments that helps.

Regardless of how it worked, they said acupuncture appears to be a relatively safe and painless way of easing an aching back, especially when traditional medicine alone fails.