Consider treating patients with acute low back pain with naproxen only, as adding cyclobenzaprine or oxycodone/acetaminophen to scheduled naproxen does not improve functional assessment at 7 days or 3 months and increases adverse effects.
Strength of recommendation
B: Based on a high-quality, randomized controlled trial (RCT).1
Friedman BW, Dym AA, Davitt M, et al. Naproxen with cyclobenzaprine, oxycodone/acetaminophen, or placebo for treating acute low back pain: a randomized clinical trial. JAMA. 2015;314:1572-1580.
A 46-year-old man presents to the emergency department (ED) with low back pain (LBP) after helping a friend move a couch 3 days earlier. He denies any direct trauma to his back and describes the pain as a spasm in his lumbar spinal region with no radicular symptoms. The pain worsens with prolonged standing and any position changes. He has tried acetaminophen with no benefit. You diagnose a lumbar muscular strain. What medications should you prescribe to help relieve his LBP and improve his overall function?
Acute LBP prompts close to 2.7 million ED visits annually in the United States.2 It leads to persistent subjective impairment and continued analgesic usage at 7 days (impairment 70%, analgesic use 69%) and at 3 months (48% and 46%, respectively) after ED discharge.3 Systematic reviews show that monotherapy with nonsteroidal anti-inflammatory drugs (NSAIDs) or muscle relaxers is better than placebo for relieving pain.4,5 A secondary analysis of patients (N=715) from a prospective cohort study showed that patients prescribed opiates for LBP had worse functioning at 6 months than those not prescribed opiates.6
Monotherapy or combination therapy for LBP? That is the question
Because medications used for LBP have different mechanisms of action, clinicians frequently combine them in an attempt to improve symptoms and function.2 Current evidence evaluating combination therapy demonstrates mixed results. A large RCT (N=867) showed that the combination of cyclobenzaprine and ibuprofen led to lower subjective pain intensity, but did not result in self-reported pain improvement (based on answers to the Patient Global Impression of Change and the Oswestry Disability Index) than cyclobenzaprine alone. However, a small RCT (N=40) combining naproxen with cyclobenzaprine demonstrated improved LBP and spasm compared to naproxen alone.7,8
This study sought to determine the benefit of treating acute LBP with cyclobenzaprine or oxycodone/acetaminophen in combination with an NSAID compared to treatment with an NSAID alone.
Adding second pain reliever to the NSAID provided no significant benefit
This double-blinded RCT enrolled 323 adult patients presenting to an ED with ≤2 weeks of nontraumatic, nonradicular LBP, which was defined as pain between the lower border of the scapulae and the upper gluteal folds.1 Participants had a score of >5 on the Roland-Morris Disability Questionnaire (RMDQ), which measures functional impairment due to LBP (range: 0-24). Patients were excluded if they had radicular pain radiating below the gluteal folds, direct trauma to the back within the previous month, pain duration >2 weeks, or a recent history of >1 LBP episode per month. Patients with current or past chronic opioid use were also excluded.
All participants received 10 days’ worth of naproxen (500 mg twice daily). They were then randomized to receive either: oxycodone 5 mg/acetaminophen 325 mg; cyclobenzaprine 5 mg; or placebo, with instructions to take one to 2 tablets prn every 8 hours for 10 days. They were told that if one tablet afforded sufficient relief, there was no need to take the second one, but if the first tablet did not provide relief within 30 minutes, they should take the second one. All patients also received a 10-minute educational session emphasizing the role of exercise, stretching, physical/massage therapy, and other non-pharmacologic interventions.
The primary outcome was change in the RMDQ between ED discharge and a phone call 7 days later, with a 5-point improvement in the RMDQ considered clinically significant. Secondary outcomes at 7 days and 3 months after ED discharge included subjective description of worst pain, frequency of LBP pain, frequency of analgesic use, satisfaction with treatment, median number of days to return to work and usual activities, need for follow-up health care visits, and opioid use. Investigators also asked about any adverse effects at 7 days and 3 months.
At 7 days, patients randomized to naproxen plus placebo improved on reported RMDQ scores by a mean of 9.8 points, naproxen plus cyclobenzaprine by 10.1 points, and naproxen plus oxycodone/acetaminophen by 11.1 points. Between group differences in mean RMDQ changes showed no statistically significant differences with placebo vs cyclobenzaprine (0.3 points; P=.77), placebo vs oxycodone/acetaminophen (1.3 points; P=.28), and cyclobenzaprine vs oxycodone/acetaminophen (0.9 points; P=.45).