C hronic non-cancer-related pain (CNCP) includes chronic pain of a nociceptive or neuropathic nature with variable influence by psychological and socioenvironmental factors. Opioids are the most potent analgesics available and are well established for the treatment of severe acute, 1 surgical 2 and cancer pain.3 However, their use to ameliorate CNCP is still controversial because of the side effects of opioids, the physical tolerance they build up (with the related withdrawal reactions and possibility of addiction) and anxiety over disapproval by regulatory bodies. 4The prevalence of CNCP varies according to the type of pain and the population studied. A study conducted in the United Kingdom in a community in the greater London area to quantify the prevalence of chronic pain found that 46.5% of the general population reported chronic pain; low-back problems and arthritis were the leading causes.5 A recent epidemiological study in Denmark 6 found that nearly 130 000 adults, corresponding to 3% of the Danish population, regularly used opioids. CNCP had a prevalence of 19%, and 12% of those who had CNCP used opioid medications.The objectives of this review were 4-fold: to determine the efficacy of opioids for CNCP compared with placebo; to compare the effectiveness of opioids for CNCP with that of other drugs; to identify categories of CNCP with better response to opioids; and to determine the most common side effects and complications of opioid therapy for CNCP, including incidences of opioid addiction and sexual dysfunction. MethodsWe followed the QUOROM guidelines for reporting metaanalyses of randomized controlled trials.7 We searched the literature up to May 2005 through the OVID interface: MEDLINE (from 1960), EMBASE (from 1988), the Cochrane Database of Systematic Reviews, the Cochrane Controlled Trials Register (CENTRAL), the ACP Journal Club and DARE. We also reviewed the reference lists in the articles, reviews and textbooks retrieved. Our search strategies for MEDLINE and EMBASE are available online as Appendix 1 and Appendix 2, respectively (all appendices for this article are available at www.cmaj.ca /cgi/content/full/174/11/1589/DC1). A single reviewer (J.A.S.) ran the electronic searches and entered the data into Reference Manager 10, removing all duplicates.Each of 2 independent reviewers (A.D.F., J.A.S.) screened Methods: This meta-analysis was carried out with these objectives: to compare the efficacy of opioids for CNCP with other drugs and placebo; to identify types of CNCP that respond better to opioids; and to determine the most common side effects of opioids. We searched MEDLINE, EMBASE, CENTRAL (up to May 2005) and reference lists for randomized controlled trials of any opioid administered by oral or transdermal routes or rectal suppositories for CNCP (defined as pain for longer than 6 mo). Extracted outcomes included pain, function or side effects. Methodological quality was assessed with the Jadad instrument; analyses were conducted with Revman 4.2.7.Results: Included were 41 randomized tr...

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In assessment of chronic pain, the evidence from epidemiologic studies makes it clear that chronic pain can best be understood in the context of psychosocial factors.

Psychosocial and behavioural factors play a significant role in the experience, maintenance, and exacerbation of pain. Self-management is an important complement to biomedical approaches. Cognitive-behavioural therapy alone or within the context of an interdisciplinary pain rehabilitation program has the greatest empirical evidence for success. As none of the most commonly prescribed treatment regimens are sufficient to eliminate pain, a more realistic approach will likely combine pharmacological, physical, and psychological components tailored to each patient's needs.