No additional benefit for low back pain when naproxen is combined with adjunct treatment, study finds

Naproxen appears to offer similar benefit for acute, nontraumatic back pain when used alone and when combined with other drugs, according to a new study.

Researchers performed a randomized, double-blind, 3-group study of patients who presented to an urban ED in New York City with nontraumatic, nonradicular low back pain that had lasted 2 weeks or less and who had a Roland Morris Disability Questionnaire (RMDQ) score greater than 5 on a 24-point scale (0=no functional impairment; 24=maximum functional impairment). The study began in April 2012, and follow-up was completed in December 2014. The primary outcome was improvement in function as measured by the RMDQ at 1 week after ED discharge. Study results appeared in the Oct. 20 Journal of the American Medical Association.

Three hundred twenty-three patients were considered eligible to participate in the study. All patients received 20 tablets of naproxen, 500 mg, to be taken twice daily. One hundred seven were randomly assigned to also receive 60 tablets of placebo; 108 were randomly assigned to also receive 60 five-mg tablets of cyclobenzaprine; and 108 were randomly assigned to also receive 60 tablets of oxycodone/acetaminophen (5 mg/325 mg). Patients were told to take 1 or 2 of the adjunct tablets every 8 hours as needed for low back pain. All patients also participated in a 1-minute educational session on low back pain before ED discharge.

The mean age of study patients was 39 years in the placebo group, 38 years in the cyclobenzaprine group, and 39 years in the oxycodone/acetaminophen group. Fifty-one percent of the 323 included patients were men, and 49% were women. Median RMDQ scores were high at baseline in all of the study groups: 20 (interquartile range [IQR], 17 to 21) in the placebo group, 19 (IQR, 17 to 21) in the cyclobenzaprine group, and 20 (IQR, 17 to 22) in the oxycodone/acetaminophen group. One week after ED discharge, mean improvement in RMDQ score in these groups was 9.8, 10.1, and 11.1, respectively. The between-group difference in mean RMDQ improvement was 0.3 for cyclobenzaprine versus placebo (P=0.77), 1.3 for oxycodone/acetaminophen versus placebo (P=0.28), and 0.9 for oxycodone/acetaminophen versus cyclobenzaprine (P=0.45).

More than half of all study patients reported that they still needed medication for low back pain at 1-week follow-up. Adverse effects were more common in the cyclobenzaprine group and the oxycodone/acetaminophen group than in the placebo group (33%, 40%, and 21%, respectively). Most patients' low back pain had resolved by 3 months after the ED visit, but 26%, 24%, and 19% of those in the placebo, cyclobenzaprine, and oxycodone/acetaminophen groups, respectively, reported that they still used medication for low back pain.

The authors noted that their results may not be generalizable and that they did not evaluate how adequately patients were blinded, among other limitations. However, they concluded that adding a muscle relaxant or an opioid plus acetaminophen to naproxen does not improve pain or functional outcomes at 1 week in patients who present to an ED with low back pain. “These findings do not support the use of these additional medications in this setting,” they wrote.