A recent double-blinded, RCT from JAMA investigated the relative efficacies of naproxen + placebo, naproxen + cyclobenzaprine and naproxen + oxycodone/acetaminophen on functional impairment in acute onset (<2 weeks), non-traumatic, non-radicular low back pain in the non-elderly (<64). 

Their findings: Of 390 patients that met inclusion criteria, there was no added benefit on functional impairment from opioids/cyclobenzaprine.  There were also more adverse effects with those medications. (Adverse events included: drowsiness, dizziness, n/v, and stomach irritation.) Functional impairment was measured at 1-week and then 3-months post-ED visit.

Although their primary outcome was functional impairment, they also investigated adherence, utilization of the medication, desire for same medication, days to return to work and self-reported pain.  There was minimal difference in these outcomes, excepting more patients in the opiate group reported mild/no pain than the other two groups (difference, 18% [95% CI, 3%-33%]; NNT, 6[95%CI, 3-37]).  This is a more subjective metric, but something to consider.

The take-home: for non-elderly patients with acute onset, non-traumatic, non-radicular LBP, naproxen alone is likely sufficient and associated with less adverse effects.  However, many ED LBP patients do not meet this criteria.  Additionally, given that 46% reported continued analgesic use at 3 months, it would be important to ensure no adverse effects of chronic NSAID use if this pattern continued 2/2 continued pain.

Friedman BW, et al. Naproxen with Cyclobenzaprine, Oxycodone/Aceaminophen, or Placebo for Treating Acute Low Back Pain: A Randomized Clinical Trial. JAMA 2015;314(15):1572-80.