A new study on cannabis use for pain has found the need for caution around use of the drug as there is no clear evidence of its efficacy against pain.
The Pain and Opioid IN Treatment (POINT), conducted by UNSW Sydney, looked at 1500 people prescribed opioids for non-cancer pain over a four-year period and how using cannabis affected their pain and opioid use.
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Other studies conducted before POINT have focused on a shorter time, typically around three months, and excluded patients with complex physical and mental health problems.
Patients in the POINT study who used cannabis for pain management were found to have greater pain and anxiety, coped less well with pain and reported the pain was interfering more with daily life.
There wasn't any clear indication cannabis reduced pain severity or led the participants to reduce their opioid use.
Study lead author Dr Gabrielle Campbell admitted there were some caveats to the study, such as the fact most of the participant's accessed cannabis illegally for the first few years of the study.
She also said 20 percent of the study participants stopped taking part. Dr Campbell says this was due to legal and access difficulties.
Overall the pain reported by patients who used cannabis for pain was significantly higher than those who did not use cannabis.
"Those using cannabis with the intent of relieving their pain may comprise a patient population with more distress and poorer coping mechanisms as evidenced in our study by the lower pain self-efficacy scores for people who used cannabis," Dr Campbell said.
"It may be that in the absence of cannabis use, pain severity and interference may have been worse. It is difficult to disentangle this based on the current study."