Group therapy can provide a cost-effective way of treating lower back pain, a study shows.

After six one and a half hour sessions of the talking therapy the participants still showed improvements a year later, the trial published in the Lancet revealed.

All of the 701 patients taking part in the study were given general advice about remaining active, avoiding bed rest and taking pain medication.

While a control group received no further intervention, 468 participants went on to have an individual assessment and six sessions of cognitive behavioural therapy (CBT) in groups of eight.

During the therapy participants discussed beliefs about doing physical activity, countering negative thoughts, and relaxation.

Those who underwent the therapy scored significantly better on questionnaires designed to measure pain and disability.

They were more positive about being able to deal with their pain and less fearful about their situation.

The treatment was also relatively cheap, at £187 for the six sessions.

The study, led by Professor Sarah Lamb, at the University of Warwick, found: "Compared with advice alone, advice plus cognitive behavioural intervention was associated with significant benefits in nearly all outcomes.

"Effective treatments that result in sustained improvements in low-back pain are elusive.

"This trial shows that a bespoke cognitive behavioural intervention package, BeST, is effective in managing subacute and chronic low-back pain in primary care."

The treatment also compared favourably to other ways of combating back pain such as acupuncture and teaching correct posture.

The authors wrote: "Unlike many of these other treatments the benefits of cognitive behavioural intervention were broad ranging and maintained at 12 months, suggesting that these benefits will translate into substantial health gain at a population level."

Persistent low-back pain is ranked as one of the top three most disabling conditions in the developed world.

Dr Laxmaiah Manchikanti, from the Pain Management Center of Paducah, in Kentucky in the US, said the study "showed rather impressive results".

He said: "The results suggest that cognitive behavioural therapy is an excellent option for primary care physicians before they seek speciality consultations for their patients."