Whether your doctor prescribes potent opioid drugs for your back pain can depend on some unlikely factors: where you live, what type of insurance you have, and your educational level and income.

New research concludes that lesser-educated, lower-income patients and those living in the South are more likely to be given opioids, which are sometimes referred to as narcotics, are prescribed for their potent pain-killing ability, and have the potential for addiction.

Xuemei Luo, a research associate at the Duke University Medical Center, and her team analyzed data from 1996 to 1999 in the Medical Expenditure Panel Survey, a national survey conducted by the government. The findings appear in the April 15 issue of Spine.

“To my knowledge, there has been no national study to examine patterns of opioid use among individuals with back pain in the United States,” Luo said. “We looked at the pattern of use and the trend of use. We found there is a wide variation in opioid use among individuals with different education levels and income.”

In the study, Luo evaluated the use of codeine, morphine, hydromorphone, hydrocodone, oxycodone, methadone, fentanyl and others.

In all, almost 9,000 survey respondents from 1996 through 1999 reported back pain, defined for the study as pain experienced in the spine area.

Overall, opioid use rates increased slightly from 1996 to 1999. During 1996, 11.6 percent of those surveyed had at least one opioid prescription; by 1999 it was 12.6 percent. The rate of oxycodone use doubled during the four-year period. Hydrocodone also increased, but at a slower pace.

Doctors in the South were more likely than those in other regions to prescribe the opioids, Luo found.

The big surprise, she said, was that patients with public insurance rather than private insurance were more likely to be on opioids. In addition, patients with less than a 12th-grade education consistently used more opioids, with rates ranging from 13.1 percent to 14.5 percent during the four-year period; those with a greater than 12th-grade education ranged from 7.6 percent to 10.8 percent. And patients in low-income families were also more likely to get opioids, with a range of 12.8 percent to 15.9 percent, compared to a range of 8.5 percent to 10.3 percent for high-income families. Luo said she did not evaluate these differences.

Back pain is a major health-care concern, Luo noted, with about 20 percent of adult Americans suffering at least one episode during a one-year period. An earlier study by Luo showed health-care expenses for back pain patients totaled more than $90 billion annually, with approximately $26 billion of that amount directly attributable to treating the pain.

Other experts, however, had some criticisms of the study.

For one thing, it didn’t delve into some important information, said Dr. Arya Nick Shamie, director of the Comprehensive Spine Center at Santa Monica UCLA Medical Center.

“We have to understand what the source of the back pain was to begin with,” he said. “We have to look at whether these patients needed opioid treatment.”

“If you have a patient with disk herniation and severe leg pain, if you put them on opioids you have not treated the cause of the pain, and opioids would not be a good treatment,” he explained.

Even with the missing links, however, the study does give some good advice for back pain patients, said Shamie and his colleague, Dr. David Fish, an assistant professor of physical medicine and rehabilitation at UCLA.

“You put someone on opioids as a last resort,” Fish said. “Make sure you have tried other options for treatment in conjunction with, or before, narcotics.”

Added Shamie: “The most important thing is to find out the reason for your back pain before you commit to opioid treatment. There might be something else you can do.”