National guidelines advise that 90 per cent of the thousands who suffer lower back pain will fully recover within six weeks.
But this estimate is overly optimistic, says Sydney specialist Professor Chris Maher, who led a study of almost 1,000 Australians published in the British Medical Journal on Monday.
It found that two months on, only 50 per cent had fully recovered from the original episode of pain, even with treatment, and after a year about 40 per cent reported their back pain persisted.
About a third had to adjust their work hours or duties as a result of their injury.
Recovery was slowest for people who had lodged compensation claims, older people, and those who delayed seeking medical attention.
"These results challenge the accepted view that recovery is rapid following an episode of acute low back pain," said Prof Maher, of The George Institute for International Health.
"For many people back pain becomes a long-term problem that severely impacts their life, and this is despite receiving what we think is the best possible care.
"We clearly need to rethink our approach."
About 20 per cent of the Australian population suffers from lower back pain at any one time, a phenomenon which costs the country about $1 billion a year to treat.
To analyse the long term prognosis of the typical patient, Prof Maher and his colleagues tracked 973 people with acute low back pain for one year.
Each was managed by a doctor, physiotherapist or chiropractor who followed national treatment guidelines.
The report concludes that recovery was general "slow and incomplete", even though every clinician was fully trained to provide best practice care, and there was no clear way to improve the situation, they said.
"At the moment it is unclear how better health outcomes can be achieved," the report states.
Prof Maher said the results showed there was substantial room for improvement in lower back pain management, and suggests the compensation system should be a target for reform.
"People within this system do much worse than those outside of it," Prof Maher said.
"More work needs to be done as this is an extremely complex system."
