By Pat Anson, Editor

People with chronic lower back pain are more likely to have used illicit drugs -- including marijuana, cocaine, heroin and methamphetamine -- compared to those without back pain, according to new research published in the journal Spine.

The study also found that people with lower back pain who had used illicit drugs were somewhat more likely to have an active prescription for opioid pain medication (22.5% vs. 15%).

Lower back pain is the world’s leading cause of disability and most people will suffer from it at least once in their lives. Although nearly a quarter of the opioid prescriptions written in the U.S. are for low back pain, medical guidelines often recommend against it.

Researchers analyzed data from over 5,000 U.S. adults who participated in a nationally representative health study and found that nearly half (49%) of those who reported lower back pain admitted having a history of illicit drug use, compared to 43% of those without back pain.

Current use of illicit drugs (within the past 30 days) was much lower in both groups; 14% versus nine percent.

The study did not differentiate between recreational and medical marijuana use, nor did it draw a distinction between marijuana use in states where it is legal and where it is not. All marijuana use was considered "illicit."

All four illicit drugs in the survey were more commonly used by people with low back pain compared to those without back pain. Rates of lifetime use were 46.5% versus 42% for marijuana; 22% vs. 14% for cocaine; 9% vs. 5% for methamphetamine; and 5% vs. 2% for heroin.

Researchers said there was no evidence that illicit drug use causes lower back pain, only that there was an association between the two that bears watching when opioids are prescribed.

“The association between a history of illicit drug use and prescription opioid use in the cLBP (chronic lower back pain) population is consistent with previous studies, but may be confounded by other clinical conditions,” said lead author Anna Shmagel, MD, Division of Rheumatic and Autoimmune Diseases at the University of Minnesota.

“Mental health disorders, for example, have been associated with both illicit substance use and prescription opioid use in the chronic low back pain population. In the context of management, however, illicit drug abuse is predictive of aberrant prescription opioid behaviors. As we face a prescription opioid addiction epidemic, careful assessment of illicit drug use history may aid prescribing decisions.”

In a recent analysis of prescriptions filled for 12 million of its members, pharmacy benefit manager Prime Therapeutics found that nearly a quarter of the opioid prescriptions were written to treat low back pain.

"Our analysis found low back pain was the most common diagnosis among all members taking an opioid, even though medical guidelines suggest the risks are likely greater than the benefits for these individuals," said Catherine Starner, PharmD, lead health researcher for Prime Therapeutics.

In a 2014 position paper, the American Academy of Neurology said opioids provide “significant short term pain relief” for low back pain, but there was “no substantial evidence” that long term use outweighs the risk of addiction and overdose.