People with chronic low-back pain can benefit from cognitive behavioral therapy, a new British report shows.

Low-back pain is one of the most costly and disabling health problems in developed countries, the researchers write in The Lancet, but so far effective treatment has been lacking.

When they added group therapy sessions to standard care — which includes pain medication and advice to stay active — the proportion of patients who got better doubled.

In addition, the benefits lasted longer and cost less than half of that of other interventions such as acupuncture.

"Unlike many of these other treatments," the researchers write, "the benefits of cognitive behavioral intervention were broad-ranging and lasted 12 months, suggesting that these benefits will translate into substantial health gain at a population level."

For the study, researchers from the University of Warwick enrolled 701 people with troublesome daily pain and stiffness in the back and buttocks. Each person was randomly assigned to receive either standard care or standard care and cognitive behavioral therapy.

Experienced nurses or psychologists worked with the 468 people in the therapy group, who received one individual session and six group sessions.

The therapists focused on behaviors and beliefs about physical activity and made patients try to counter negative thoughts.

Over the course of a year, the researchers tested patients' pain and disability. After a year, those participating in talk therapy experienced twice the improvement of patients receiving only standard care.

The percentage of patients reporting recovery was 60 percent in the therapy group and 30 percent in the standard group.