In patients with acute, nontraumatic low back pain, adding cyclobenzaprine or oxycodone/acetaminophen to naproxen alone did not improve functional outcomes or pain at 1-week follow-up in a new randomized study.
“Naproxen alone was just as good as using it in combination with the muscle relaxant or the opioid,” lead author Benjamin W. Friedman, MD, Albert Einstein College of Medicine, Bronx, New York said, “so there is no reason to add in these other drugs. Patients are probably best advised to take naproxen or another NSAID [nonsteroidal anti-inflammatory drug] on its own.”
Dr Friedman explained that the study to address the clinical uncertainly about how to treat low back pain, a very common condition accounting for 2.4% of visits to US emergency departments. All these medications tested are popular options for treatment. And although each has been shown to be better than placebo as monotherapy, there are few data on whether combinations are better than use on their own.
The current study, published in the October 20 issue of JAMA, included 323 patients presenting to the emergency department with nontraumatic, nonradicular lower back pain of 2 weeks’ duration or less and a score greater than 5 on the Roland-Morris Disability Questionnaire (RMDQ), a 44-item questionnaire commonly used to measure low back pain and related functional impairment.
All patents were given naproxen, 500 mg, to be taken twice daily. They were then randomly assigned to placebo; the skeletal muscle relaxant cyclobenzaprine, 5 mg; or the opioid oxycodone, 5 mg, plus acetaminophen, 325 mg, each to be taken every 8 hours, as needed.
The primary outcome — improvement in RMDQ score at 1 week — was similar in all three groups, with no statistically significant differences.
Table. Improvement in RMDQ at 1 Week
| Endpoint | Placebo | Cyclobenzaprine | Oxycodone/Acetaminophen |
| Improvement in RMDQ at 1 wk | 9.8 | 10.1 | 11.1 |
Subgroup analysis did suggest some effect in patients who regularly took the opioid/acetaminophen combination close to maximum prescribed dose. Dr Friedman noted: “They showed a slight benefit on the pain outcome (not the primary outcome), but this was only moderate — the number needed to treat was 6 to prevent 1 patient from having moderate to severe pain, and this needs to be balanced by a number to harm of 5 due to side effects, so I would not recommend it.”
He noted that while his advice from this study was to stick with NSAIDs alone, he realized that many patients will continue to have pain and that new approaches are urgently needed.
“In this study, 50% of patients still had moderate to severe pain at 1 week and 25% at 3 months in all three groups, so the medications we have at the moment don’t seem to be the answer,” he commented. “The problem will be that clinicians and patients are frustrated by not having anything very effective to treat this low back pain. It is difficult to tell patients we have nothing else to offer them other than NSAIDs. But if you explain all the evidence they should accept the advice.”
He added: “There are other varieties of muscle relaxants and opioids out there, but there is no reason to believe they would be any different from the agents we tested. Some people use benzodiazepines or complementary therapies, such as acupuncture, massage, or chiropractor treatment, but these have not been clearly established to be beneficial. I think the way forward is to study combinations of medications and various complementary therapies.”
Dr Friedman noted that any of the three drug categories could be used as monotherapy, but NSAIDs are normally regarded as first choice probably because of the adverse effect profiles. “But if the patient has a stomach ulcer you wouldn’t use an NSAID, and if they were a truck driver you wouldn’t use a muscle relaxant because of the sedative side effects. The opioids have their own side effect concerns, but it wouldn’t be unreasonable to prescribe them if the patient can’t take NSAIDs or muscle relaxants.”
He added that he was not overly worried about the addictive potential of opioids in this scenario: “I’m not convinced that a short course of opioid for an acute problem will be a major issue. It is uncommon enough that it shouldn’t cause a clinician to treat acute pain inadequately,” he said.