Nine of the Medicaid plans covered steroid injections, but only three covered psychological counseling.

"We were perplexed by the absence of coverage language on psychological interventions," Alexander says. "It's hard to imagine that insurers wouldn't cover that."

Even for physical therapy, a well-established method for relieving lower back pain, insurance coverage was inconsistent.

"Some plans covered two visits, some six, some 12; some allowed you to refer yourself for treatment, while others required referral by a doctor," Alexander says. "That variation indicates a lack of consensus among insurers regarding what model coverage should be, or a lack of willingness to pay for it.”

The Bloomberg study is being published online in the journal JAMA Network Open. It was funded by the U.S. Department of Health and Human Services, National Institutes of Health and the Centers for Disease Control and Prevention.

Lower back pain is the world’s leading cause of disability, but there is surprisingly little consensus on the best way to treat it. A recent series of reviews by an international team of experts in The Lancet medical journal found that low back pain is usually treated with bad advice, inappropriate tests, risky surgeries and painkillers.

“The majority of cases of low back pain respond to simple physical and psychological therapies that keep people active and enable them to stay at work,” said lead author Rachelle Buchbinder, PhD, a professor at Monash University in Australia. “Often, however, it is more aggressive treatments of dubious benefit that are promoted and reimbursed.”

The authors recommend counseling, exercise and cognitive behavioral therapy as first-line treatments for short-term low back pain, followed by spinal manipulation, massage, acupuncture, meditation and yoga as second line treatments. They found limited evidence to support the use of opioids for low back pain, and epidural steroid injections and acetaminophen (paracetamol) are not recommended at all.