October 02, 2024
JAMA Network Open
TAKE-HOME MESSAGE
- This systematic review of 44 studies assessed the efficacy of long-term use of skeletal muscle relaxants for chronic pain. Skeletal muscle relaxants were effective for neck pain, cramping pain, and trigeminal neuralgia. The effectiveness of skeletal muscle relaxants for fibromyalgia and low back pain was comparable to that of placebo. The most common adverse effects were dry mouth and sedation. Of note, the majority of the included studies had a short-term follow-up duration of 6 weeks or less.
- Clinicians should consider deprescribing muscle relaxants if pain goals are not met to avoid adverse effects, particularly for conditions in which the effects of these medications were comparable to those of placebo.
– Owen Hamilton, MD, MPHS
IMPORTANCE
Stricter opioid prescribing guidelines have increased prescriptions of skeletal muscle relaxants (SMRs) for chronic pain, but the efficacy of long-term use of SMRs for chronic pain is unknown.
OBJECTIVE
To systematically review the effectiveness or efficacy of long-term use of SMRs for chronic pain.
EVIDENCE REVIEW
Two reviewers systematically searched Ovid MEDLINE, Embase (Ovid), Web of Science, CINAHL, and Cochrane through December 4, 2023. They included articles published in English, Spanish, or Italian. Only randomized clinical trials (RCTs) and cohort studies with comparator groups evaluating at least 1-month duration of SMRs for chronic pain were included. The reviewers dually reviewed data abstraction, risk-of-bias, and quality. They characterized studies by chronic pain syndrome: low back pain, fibromyalgia, headaches, painful cramps or spasticity, and other syndromes.
FINDINGS
A total of 30 RCTs with 1314 participants and 14 cohort studies with 1168 participants assessed SMRs for chronic pain. Studies were primarily short-term (4-6 weeks). Nine unique SMRs were represented by the studies identified. Eleven studies (25%) examined baclofen, 8 (18%) examined tizanidine, and 7 (16%) examined cyclobenzaprine. Evidence for effectiveness was strongest for SMRs used for trigeminal neuralgia, neck pain, and painful cramps; evidence suggested SMRs for fibromyalgia, low back pain, and other syndromes were not more beneficial than placebo. The most common adverse effects were sedation and dry mouth. RCTs had a low to moderate risk of bias, and the quality of cohort studies was fair to good.
CONCLUSIONS AND RELEVANCE
In this systematic review of long-term use of SMRs for chronic pain, findings suggest that their long-term use may benefit patients with painful spasms or cramps and neck pain; their long-term use for low back pain, fibromyalgia, and headaches did not appear to be beneficial. Clinicians should be vigilant for adverse effects and consider deprescribing if pain-related goals are not met.