- Rainer Freynhagen, head of department, associate professor12,
- Gerd Geisslinger, full professor, head of institute3,
- Stephan A Schug, professor and chair4
- 1Department of Anaesthesiology, Critical Care Medicine, Pain Therapy, and Palliative Care, Benedictus Hospital Tutzing, Bahnhofstraße 5, 82327 Tutzing, Germany
- 2Department of Anaesthesiology, Technical University Munich, Munich, Germany
- 3Pharmazentrum Frankfurt/ZAFES, Institute of Clinical Pharmacology, University Hospital, Goethe University Frankfurt, 60590 Frankfurt am Main, Germany
- 4Pharmacology, Pharmacy and Anaesthesiology Unit, School of Medicine and Pharmacology, University of Western Australia, Pain Medicine, Royal Perth Hospital, Perth WA 6847, Australia
- Correspondence to: R Freynhagen
- Accepted 25 March 2013
A 36 year old carpenter has a six month history of lower back pain with no specific clinical or radiological findings. As his pain has not responded to paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs), he asks his doctor if he can have “stronger painkillers” such as morphine.
What are opioids?
Opioids are a group of compounds that act by binding to opioid receptors (μ, κ, and δ), which are widely distributed in the brain, spinal cord, and peripheral tissues. They are the mainstay in the management of cancer pain, but published data show a continual increase in the volume of prescribed opioids to manage moderate to severe, chronic, non-cancer pain.1 2
Changes in attitude and aggressive marketing have driven a dramatic increase in use, with more adverse events, including deaths from overdose (now the second leading cause of accidental death in the US).3 Proponents claim that opioids are underused for chronic pain,4 but lack of good scientific data has prevented the formulation of evidence based guidelines for their use, especially in primary care.
How well do opioids work in chronic non-cancer pain?
Several meta-analyses of the effectiveness of opioids have been published. Most of the randomised clinical trials summarised in these meta-analyses were funded by the pharmaceutical industry and report heterogeneous, short term outcomes in highly selected patients. Non-randomised and uncontrolled observational studies make up the rest of the literature. Nevertheless, most studies have consistently shown some effectiveness in chronic non-cancer pain by reducing pain intensity. In particular, meta-analyses show the efficacy of opioids in neuropathic pain,5 6 7 although most guidelines regard opioids only as second or third line treatment for such pain because of their risk:benefit profile.8 9 The data are even less encouraging for chronic non-neuropathic pain, the focus of this paper. A 2009 Cochrane review of 10 randomised or quasi-randomised controlled trials compared …