Surgery to relieve chronic lower back pain is no better than intensive rehabilitation and nearly twice as expensive, researchers said.

Low back pain is one of the world's most common complaints. In the 25-nation European Union, it affects over 40 million workers and accounts for nearly half of all sick days.

Researchers at the Nuffield Orthopaedic Center in Oxford, England found little difference when they compared the effects of surgery with rehabilitation on nearly 350 sufferers.

"This is strong evidence that intensive rehabilitation is a good thing to do for people with chronic back pain who are thinking of having about having operations," said Jeremy Fairbank, an orthopaedic surgeon at the center.

"The ultimate outcome ... is there is not much difference," he told Reuters.

Fairbank and his colleagues studied 349 back pain sufferers who either had spinal fusion surgery or intensive rehabilitation involving exercises and cognitive behavioral therapy.

Thirty patients in the therapy group later had surgery.

The researchers, whose findings are reported online by the British Medical Journal, concluded that there was no evidence that surgery was any better.

But the average cost for a surgery patient was 7,830 pounds ($14,400), compared to 4,526 pounds for rehabilitation.

"In the short term, compared with intensive rehabilitation, surgical stabilisation of the spine as first line treatment for chronic low back pain patients who have already failed standard non-operative care seems not to be cost effective," said Helen Campbell of the University of Oxford in the journal.

Doctors suspect chronic back pain is caused by a combination of normal wear and tear on the joints of the back and poor muscle control. It is treated with physiotherapy, osteopathy, chiropody and surgery or a combination of treatments.

"The peak prevalence is in young middle age," said Fairbank.

He added that surgeons offering spinal fusion surgery, in which one or more vertebrae of the spine are joined to stabilize a section of the spine, should explain all the options to patients.