Cannabis for medical use versus opioids for chronic non-cancer pain
Why was this study conducted?
Chronic non-cancer pain impacts 20% of the global population and is associated with reduced quality of life, disability and considerable socioeconomic burden. Opioids are commonly prescribed for chronic non-cancer pain and may provide improvement in pain relief, physical functioning and quality of sleep compared with placebo; however, they are also associated with harms including addiction, overdose and death. There is a growing interest in cannabis as an alternative to long-term opioid use, and countries increasingly permit therapeutic use of cannabis. Two-thirds of cannabis for medical use users endorse management of chronic pain as their indication for use. Despite the increasing availability of cannabis for medical use, its use for chronic pain remains controversial due, in part, to conflicting recommendations. A 2019 guideline from the National Institute for Health and Care Excellence made strong recommendations against the use of cannabis for chronic pain, and in 2021 the International Association for the Study of Pain (IASP) released a position statement against the use of cannabinoids for pain. Alternately, a 2021 BMJ Rapid Recommendation made a conditional recommendation to offer a trial of non-inhaled cannabis for medical use for people living with chronic pain if standard care was insufficient. The European Pain Federation also issued a position paper stating that cannabis-based medicines can be used by experienced physicians when guideline recommended first-line and second-line therapies for chronic pain do not provide sufficient benefit. The study undertook a systematic review and network meta-analysis (NMA) of randomised controlled trials (RCTs) to explore the comparative benefits and harms of cannabis for medical use and opioids for chronic non-cancer pain.
What does this study add?
Ninety trials involving 22,028 patients were eligible for review, among which the length of follow-up ranged from 28 to 180 days. Moderate certainty evidence showed that opioids provide small improvements in pain, physical functioning and sleep quality versus placebo; low to moderate certainty evidence supported similar effects for cannabis versus placebo. Neither was more effective than placebo for role, social or emotional functioning (all high to moderate certainty evidence). Moderate certainty evidence showed there is probably little to no difference between cannabis for medical use and opioids for physical functioning (weighted mean difference (WMD) 0.47 on the 100-point 36-item Short Form Survey physical component summary score, 95% credible interval (CrI) ?1.97 to 2.99), and cannabis resulted in fewer discontinuations due to adverse events versus opioids (OR 0.55, 95% CrI 0.36 to 0.83). Low certainty evidence suggested little to no difference between cannabis and opioids for pain relief (WMD 0.23?cm on a 10?cm Visual Analogue Scale (VAS), 95% CrI ?0.06 to 0.53) or sleep quality (WMD 0.49?mm on a 100?mm VAS, 95% CrI ?4.72 to 5.59).
Is there anything else I should know?
Future research should directly compare the effectiveness of opioids versus cannabis for chronic pain, and follow patients sufficiently to inform long-term benefits and harms. Trials should report all outcome measures of importance to people who live with chronic pain. Randomized trials are also needed to establish the opioid-substitution effects of cannabis for chronic pain, and observational studies to inform long-term and infrequent harms of both cannabis for medical use and opioids for chronic pain (eg, overdose and addiction).