U.S. doctors are more frequently prescribing powerful and addictive painkillers for back pain instead of the recommended conservative treatment, the Los Angeles Times reported.

Researchers at Massachusetts' Beth Israel Deaconess Medical Center and Harvard Medical School analyzed 24,000 spinal cases from 1999 to 2010 in their study, published Monday in JAMA Internal Medicine.

"Well-established guidelines for routine back pain stress conservative management, including use of nonsteroidal anti-inflammatory drugs (NSAIDs) or acetaminophen and physical therapy," wrote lead author Dr. John Mafi and his colleagues.

The study found that many doctors were doing exactly the opposite of these guidelines. During the 11-year span of the cases, narcotic painkiller prescriptions rose 51 percent while non-opiate drugs fell by the same amount.

The researchers noted a study done in 2007 in which doctors had found narcotics to provide a hardly any benefit to acute or chronic back pain.

"This is kind of concerning," said Dr. Steven Cohen, an anesthesiologist and critical care doctor at Johns Hopkins School of Medicine in Baltimore who didn't participate in the research, told Reuters. "We have increased utilization, yet we don't have better treatment outcomes."

The amount of CT scans had also gone up from seven percent in 1999 and 2000 to 11 percent in 2009 and 2010. Cohen said people with low back pain should use Tylenol or other NSAIDs.

Physical therapy remained static throughout the study's time period, but other doctor referrals, for surgery and other treatments, doubled from seven to 14 percent.

"Physicians want to offer patients treatments that are going to work sooner and patients are demanding them and sometimes it's just easier to order the MRI or order the referral," Dr. Bruce Landon, of the Harvard Medical School, said.

According to the Los Angeles Times, back and neck pain account for ten percent of visits to a person's primary care doctor and $86 billion in healthcare spending annually.

"Patients expect and want it to get better in seconds and that's not always going to happen," Landon said. "But if you give it time, work on it, do stretching and physical therapy exercises, that's what's going to make it better in the long run."