People treated for low-back pain tend to improve greatly in the first six weeks but the pain and disability in some people may linger for a year, a new review suggests.

Researchers from Australia and Britain crunched data from studies on 11,166 people in a dozen countries who were receiving care for low-back pain. An estimated four out of five Canadians will experience back pain at some point in their lives.

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Keith Swenson, who runs a family gardening business in Maple Plain, Minn., suffered disabling back pain for years, like others with the chronic condition. He recovered with an aggressive rehab program that exercises the muscles that support the back. (Jim Mone/Associated Press)

"We found that patients with acute or persistent low-back pain improved markedly in the first six weeks, but beyond this time improvement slowed," Dr. Christopher Maher, director of the musculoskeletal division at the University of Sydney, Australia, and his co-authors concluded in this week's issue of the Canadian Medical Association Journal.

"Even at one year, patients had low to moderate levels of pain and disability."

Mayer's team found average pain scores improved by almost half after six months among patients who initially showed persistent low-back pain.

In contrast, the majority of people with acute back pain lasting less than six weeks when they sought care recovered by 12 weeks.

Low-back pain is hard to prevent, Dr. Rachelle Buchbinder of Monash University in Malvern, Australia, said in a journal commentary.

Knowing "that disability, rather than low back pain, persists is an important pointer for improving our interventions," Buchbinder said.

The review did not include details on the nature of the back pain or the treatments.

Much of "the apparent benefits of any treatment for low-back pain are likely to be unrelated to the effects of specific interventions," the commentary noted.

There was no specific funding for the study.