SynthesisSchmerz (Berlin, Germany)2015

[Opioids in chronic noncancer pain-are opioids superior to nonopioid analgesics? A systematic review and meta-analysis of efficacy, tolerability and safety in randomized head-to-head comparisons of opioids versus nonopioid analgesics of at least four week's duration].

P Welsch et al.PubMed ↗Publisher ↗

No numbers read from the abstract.