A Randomized, Double-Blind, Placebo-Controlled Trial of Naproxen With or Without Orphenadrine or Methocarbamol for Acute Low Back Pain

Study objective In US emergency departments (EDs), patients with low back painare often treated with nonsteroidal anti-inflammatory drugs and muscle relaxants. We compare functional outcomes among patients randomized to a 1-week course of naproxen+placebo versus naproxen+ orphenadrineor naproxen+ methocarbamol. Methods This was a randomized, double-blind, comparative effectiveness trial conducted in 2 urban EDs. Patients presenting with acute, nontraumatic, nonradicular low back painwere enrolled. The primary outcome was improvement on the Roland-Morris Disability Questionnaire (RMDQ) between ED discharge and 1 week later. All patients were given 14 tablets of naproxen500 mg, to be used twice a day, as needed for low back pain. Additionally, patients were randomized to receive a 1-week supply of orphenadrine100 mg, to be used twice a day as needed, methocarbamol750 mg, to be used as 1 or 2 tablets 3 times per day as needed, or placebo. All patients received a standardized 10-minute low back paineducational session before discharge. Results Two hundred forty patients were randomized. Baseline demographic characteristics were comparable. The mean RMDQ score of patients randomized to naproxen+placebo improved by 10.9 points (95% confidence interval [CI] 8.9 to 12.9). The mean RMDQ score of patients randomized to naproxen+ orphenadrineimproved by 9.4 points (95% CI 7.4 to 11.5). The mean RMDQ score of patients randomized to naproxen+ methocarbamolimproved by 8.1 points (95% CI 6.1 to 10.1). None of the between-group differences surpassed our threshold for clinical significance. Adverse events were reported by 17% (95% CI 10% to 28%) of placebo patients, 9% (95% CI 4% to 19%) of orphenadrinepatients, and 19% (95% CI 11% to 29%) of methocarbamolpatients. Conclusion Among ED patients with acute, nontraumatic, nonradicular low back pain, combining naproxenwith either orphenadrineor methocarbamoldid not improve functional outcomes compared with naproxen+placebo.