OPINION: Cannabis used to top up prescribed opioids

The researchers also found that those who used cannabis in addition to opioids reported greater pain relief than those using opioids alone.

 Use of cannabis among chronic-pain patients using opioids was common. Past-year cannabis use was more than three times higher than in the general population – 13per cent of the sample had used cannabis in the past year, compared with only 4.7per cent of the general population aged over 40 years. One in six had never used cannabis for pain relief (16per cent), and a quarter (23per cent) reported that they would use cannabis for pain if they had access to it.

 The analysis of cannabis use among prescription opioid users was conducted as part of Australia’s largest  study of chronic pain sufferers using pharmaceutical opioids. Called the POINT study, it is following more than 1500 Australians over two years.

 Those in the cohort who had used cannabis for pain were younger than those who used prescription opioids only (average age of 49 compared with 59 for non-users), were more likely to report more severe pain, had been living with pain for longer and reported that their pain interfered with their lives to a great  extent. They were also more likely to have a history of substance use disorders and mental health issues.

 There is  limited research evidence on the effectiveness of cannabis use for chronic pain, either on its own or in conjunction with opioids.

 Yet despite this, and the fact that cannabis use is illegal in Australia, use of cannabis among this group was high. 

Despite scientific uncertainty about the benefits of cannabis use for medical purposes there is a significant sub-population of people living with chronic pain who report that they experience real benefits in terms of pain relief.

 Associate Professor Nicholas Lintzeris, an Addiction Medicine specialist from Sydney University has noted: ‘‘We need to know much more about the potential role of cannabinoids for chronic pain conditions.

 ‘‘We have documented that a small but significant population of chronic pain sufferers reported pain relief from their cannabis use. This group of individuals generally reported more complex and debilitating pain conditions than non-cannabis users, and less satisfactory symptom relief with conventional pain treatments such as opioid medication. It may be that cannabis use provides some additional therapeutic benefits for those not benefiting from usual treatment approaches. 

‘‘However, there is often a complex relationship between pain and other health issues – such as mental health, sleep and substance use, and much more research is required to disentangle the effects of cannabis use in chronic pain sufferers,’’ he said.

This is a group of individuals with complex clinical histories. The potential risks of long-term cannabis use need to be considered and carefully managed.

The study has been published in the international journal Drug and Alcohol Dependence. Professor Louisa Degenhardt is the lead author