Prescribing opioids and muscle relaxants to acute low back pain (LBP) patients who are already on nonsteroidal anti-inflammatory drugs (NSAIDs) does not provide additional pain relief, a new study suggests.

There are more than 2.5 million acute LBP-related visits to emergency departments in the United States annually, where patients are often treated with a combination of NSAIDs, acetaminophen, opioids or skeletal muscle relaxants, according to researchers from the Albert Einstein College of Medicine, in New York City. The investigators conducted a randomized controlled clinical trial with 323 acute LBP patients to compare the efficacy of different drug combinations that are used to treat pain. The main measures were functional outcomes using the Roland-Morris Disability Questionnaire (RMDQ) and pain ratings one week after discharge from the emergency department. All patients included in the study had a score of 5 or greater on the RMDQ (a score of 0 indicates no functional impairment; a score of 24 indicates maximum impairment).

The patients were randomly assigned to receive a 10-day course of 500 mg of naproxen with either placebo (n=108); 5 mg of cyclobenzaprine, a muscle relaxant (n=108); or 5 mg of oxycodone/325 mg of acetaminophen. The patients were instructed to take the naproxen twice a day and to take one or two tablets of the other medication every eight hours as needed.

The researchers found no additional pain relief in the patients given cyclobenzaprine or oxycodone/acetaminophen compared with placebo at the week 1 follow-up; approximately two-thirds of all the patients experienced clinically significant improvement in acute LBP and function (Table).

Medication Type	Baseline (Median)	Improvement at Week 1 (Mean)
Placebo	20	9.8
Cyclobenzaprine	19	10.0
Oxycodone/acetaminophen	20	11.0

The difference in mean RMDQ improvement for cyclobenzaprine compared with placebo was 0.3 (98.3% CI, –2.6 to 3.2; P=0.77); for oxycodone/acetaminophen compared with placebo the difference was 1.3 (98.3% CI, –1.5 to 4.1; P=0.28); and for oxycodone/acetaminophen compared with cyclobenzaprine the difference was 0.9 (98.3% CI, –2.1 to 3.9; P=0.45).

The researchers noted that the findings do not “support the use of these additional medications” in the emergency department for the treatment of acute LBP.

The findings are published in JAMA (2015;314:1572-1580).