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Original Investigation
July 9, 2001

Cyclobenzaprine and Back Pain: A Meta-analysis

Author Affiliations

From the Departments of Medicine, National Naval Medical Center (Dr Browning), and Uniformed Services University of the Health Sciences (Drs Jackson and O'Malley), Bethesda, Md; and the Department of Medicine, Walter Reed Army Medical Center, Washington, DC (Drs Jackson and O'Malley).

Arch Intern Med. 2001;161(13):1613-1620. doi:10.1001/archinte.161.13.1613

Background  Back pain is a common problem for which cyclobenzaprine hydrochloride is frequently prescribed.

Objective  To perform a systematic review of cyclobenzaprine's effectiveness in the treatment of back pain.

Methods  We searched MEDLINE, PsycLIT, CINAHL, EMBASE, AIDSLINE, HEALTHSTAR, CANCERLIT, the Cochrane Library, Micromedex, Federal Research in Progress, and the references of reviewed articles, and contacted Merck, Sharpe and Dohme for English-language, randomized, placebo-controlled trials of cyclobenzaprine in adults with back pain. Outcomes included global improvement and 5 specific domains of back pain (local pain, muscle spasm, range of motion, tenderness to palpation, and activities of daily living). Study quality was assessed using the methods of Jadad. Summary outcomes were obtained using a random-effects model.

Results  Patients treated with cyclobenzaprine were nearly 5 times (odds ratio, 4.7; 95% confidence interval, 2.7-8.1) as likely to report symptom improvement by day 14 as were those treated with placebo. Slightly fewer than 3 individuals (2.7; 95% confidence interval, 2.0-4.2) needed treatment for 1 to improve. The magnitude of this improvement was modest, with an effect size of 0.38 to 0.58 in all 5 outcomes (local pain, muscle spasm, tenderness to palpation, range of motion, and activities of daily living). Treatment efficacy for these 5 outcomes was greatest early, in the first few days of treatment, declining after the first week. Patients receiving cyclobenzaprine also experienced more adverse effects, the most common being drowsiness.

Conclusions  Cyclobenzaprine is more effective than placebo in the management of back pain; the effect is modest and comes at the price of greater adverse effects. The effect is greatest in the first 4 days of treatment, suggesting that shorter courses may be better. Studies comparing the relative value of acetaminophen, nonsteroidal anti-inflammatory drugs, and cyclobenzaprine individually and in combination in the treatment of back pain are needed.