Lit Matters #1: SMRs No Better Than Placebo for LBP

Acute nonradicular low back pain usually improves within a week with conservative therapy. In ED patients treated with an NSAID, seven commonly used skeletal muscle relaxants performed no better than placebo on functional recovery, while cyclobenzaprine produced more adverse effects.

Acute Low Back Pain Treatment

• Placebo-level SMR benefit: Across 887 ED patients with acute nonradicular low back pain, baclofen, methocarbamol, tizanidine, diazepam, metaxalone, orphenadrine, and cyclobenzaprine were no better than placebo for 1-week functional improvement.
• Meaningful early recovery: Average Roland-Morris Disability Questionnaire scores improved by about 10 points in all groups, comfortably exceeding the 5-point threshold for clinical significance and reinforcing the usual favorable short-term course.
• Mild pain by one week: Roughly 60% to 68% of patients had no pain or only mild pain at follow-up regardless of which adjunct they received, a practical expectation-setting point worth hearing in the episode.
• No clear responder subgroup: Age, sex, baseline disability, and prior low back pain episodes did not meaningfully change outcomes, arguing against a reliable demographic profile that benefits more from adding a muscle relaxant.
• Cyclobenzaprine adverse effects: Cyclobenzaprine stood out for harm, with adverse events in 35% versus 16% on placebo, mostly drowsiness, dry mouth, dizziness, and nausea.
• NSAID-first framing: All patients received naproxen or ibuprofen, so the strongest takeaway is NSAID-based conservative care first; the unanswered NSAID-only question is one we get into in the podcast.