Despite a lack of evidence that opioids are more effective than other drugs used for chronic non-cancer pain (CNCP) there has been a large increase in the use of opioids for CNCP and concerns expressed over the risks associated with long-term use.1 An overview of Cochrane systematic reviews has assessed the occurrence and nature of adverse events associated with opioids.2 The review assessed any opioid agent (any dose, frequency or route of administration) used on a …