People who use cannabis, both medical or otherwise, are at increased risk of prescription opioid misuse – but medical cannabis users are not at higher risk of disorder
A study by US researchers has investigated potential associations between cannabis use and increased risks of prescription opioid misuse or prescription opioid use disorder.
Prescription opioid misuse was defined as prescription opioid pain reliever use in the past 12 months that was not directed by a doctor.
Prescription opioid use disorder was defined as past-year dependence or abuse screened by the diagnostic criteria in the DSM-IV.
The study drew samples from the US National Survey on Drug Use and Health (2013-16), and the National Epidemiology Survey on Alcohol and Related Conditions-III (2012-13).
It included a total of 1,295 medical cannabis users, 18,666 cannabis users (non medical), 707 cannabis dual users (both medical and non medical) and 57,196 cannabis non-users.
Propensity score matching was used to make a balanced comparison between cannabis users and non-users, with the goal of alleviating potential bias due to confounding.
The study also controlled for factors such as socioeconomic characteristics, other substance use disorders, and physical and mental health conditions.
In a secondary analysis, pain symptoms were taken into consideration.
Prevalence rates of prescription opioid misuse was 11.34% among medical cannabis users, 17.19% among cannabis dual users, 15.06% among non-medical cannabis users, and 2.96% among cannabis non-users.
The prevalence rates of prescription opioid use disorder among these groups were 2.33%, 3.87%, 2.40% and 0.44%, respectively.
All cannabis use was associated with a higher risk of prescription opioid misuse, regardless of use purposes.
Risk was greatest among non-medical cannabis users (OR = 3.15, 95%CI: 2.89-3.44, P < 0.001), followed by cannabis dual users (OR = 2.55, 95%CI: 1.78-3.65, P < 0.001) and medical cannabis users (OR = 2.15, 95%CI: 1.58-2.91, P < 0.001).
This positive association reflects findings of previous studies, said the researchers.
A higher risk of prescription opioid use disorder was observed among non-medical cannabis users (OR = 2.52, 95%CI: 2.06-3.10, P < 0.001) compared to cannabis non-users.
However there was no evidence of association between medical cannabis use or cannabis dual use, and prescription opioid use disorder.
“Our findings along with other individual-level studies suggested that medical cannabis is associated with increased risks of prescription opioid misuse,” said the University of California researchers in the journal Drug and Alcohol Review.
“On the other hand, we did not find evidence to support the long-standing concern that medical cannabis may be associated with increased risks of opioid dependence.
“We therefore encourage a holistic evaluation of its beneficial and harmful effects based on clinical evidence before medical cannabis is recommended as an alternative to prescription opioids.”
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