Are Muscle Relaxants Useful for Back Pain?

March 9, 2022

Written by Jonathan Brewer

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Skeletal muscle relaxants (SMRs) + nonsteroidal anti-inflammatory drug (NSAIDs) do not improve outcomes any more than placebo + NSAIDs in the treatment of low back pain (LBP). Even when stratified by age, sex, history of LBP, and initial severity, SMRs still did not win against placebo.

Why does this matter?
As we make a push for better non-opioid “multimodal analgesia cocktails” for low back pain, we keep searching for medications that actually work. We know that SMRs have been shown to be efficacious as monotherapy for acute LBP, but when added to a NSAIDs in the ED, is there any benefit?

Just relax…easier said than done
This was a planned secondary analysis of data from 4 randomized studies of patients with acute non-radicular low back pain. Patients were enrolled during an ED visit and received a follow-up 1 week later. The primary outcome was improvement in the Roland-Morris Disability Questionnaire (RMDQ).

Eight groups were created consisting of commonly used SMRs. All patients also received a NSAID (naproxen or ibuprofen). The mean improvement in RMDQ per group is listed below. Between-group differences were not statistically significantly different (using ANOVA), and there was no association of SMR efficacy with age, sex, or baseline severity using linear regression.

What I take from this is that SMRs aren’t the holy grail for LBP. Given these results, I wonder about the power of placebo, especially when simple intradermal sterile water injection markedly and sustainably improved back pain symptoms.

Source
The Relative Efficacy of Seven Skeletal Muscle Relaxants. An Analysis of Data From Randomized Studies. J Emerg Med. 2022 Jan 20;S0736-4679(21)00839-8. doi: 10.1016/j.jemermed.2021.09.025. Online ahead of print.

Reviewed by Clay Smith