World's largest opioid review finds they often do not work

The largest systematic review yet of opioid effectiveness in chronic pain has been published. Science Daily reports that the work, led by the University of Sydney with international collaborators, found that opioids deliver limited benefit in most chronic pain conditions.

The study pooled data from more than 600 randomized controlled trials and over 100,000 participants. Indications such as back pain, osteoarthritis, fibromyalgia, neuropathic pain and cancer pain were analyzed separately. For most indications, the average reduction in pain did not reach a clinically meaningful threshold.

The researchers report that, on a 0-10 pain-intensity scale, opioids improved scores by an average of 0.5-1 point compared to placebo. The threshold for clinical meaningfulness is typically a two-point difference. Once dependence risk and side effects are factored in, those small differences become even harder to justify.

Lead author Professor Christine Lin said: 'Our prescribing practices are based on limited evidence developed in the late 1990s and early 2000s that we can no longer accept as adequate. A modern, much broader evidence base seriously shrinks the role of opioids in chronic pain management.'

The clearest benefit was seen in cancer pain and in acute post-operative pain. In those settings, opioids remain a key component of care. By contrast, in chronic musculoskeletal pain and in central-sensitization conditions like fibromyalgia, the benefit of opioids is small and the risks are pronounced.

The review also focused on the dependence-dose relationship. About a quarter of chronic-pain patients started on low doses and then escalated met at least some dependence criteria within six months. Side effects of note include constipation, hormonal disruption, cognitive impairment and increased fall risk.

Changes in clinical guidance are expected. National pain bodies in Australia, the UK and Canada have said they are reviewing the work and will update recommendations. Updates are expected to raise the thresholds for starting opioids and widen first-line interventions such as physical therapy, cognitive behavioural therapy and exercise.

The message to patients is not dramatic. In expert commentary cited by Science Daily, Stanford pain medicine specialist Dr Sean Mackey said: 'It is true that opioids deliver important benefit to some patients, but treating them as the only option has been a mistake for years. Multimodal pain management should be standard care.'

The cost dimension matters for health systems. Off-label use and opioid-related emergency department visits make up a significant share of healthcare spending in the United States and the United Kingdom. Less opioid prescribing could lower long-term costs without worsening short-term clinical outcomes.

The researchers caution that an outright rejection of opioids would risk an increase in undertreated pain. The takeaway is not 'discard opioids' but 'use them in the right place, for the right patient, in short courses and at limited doses.' This is not medical advice; consult your doctor on pain-management decisions.