UC San Diego

Introduction and aims

Previous research suggested that cannabis use was associated with increased risks of prescription opioid misuse and use disorder. This study examined whether these associations differed by cannabis use purpose.

Design and methods

This is a secondary analysis of cross-sectional surveys with propensity score matching. Medical cannabis users (N = 1295), cannabis dual users with both medical and non-medical purposes (N = 707) and non-medical cannabis users (N = 18 666) were compared with cannabis non-users (N = 57 196) in the pooled 2013-2016 US nationally representative National Survey on Drug Use and Health. Propensity score models were applied to match cannabis non-users to cannabis users with different purposes with respect to potential confounders in individual socioeconomic characteristics, other substance use disorders and health conditions. In a matched sample, logistic regressions were used to assess associations.

Results

Propensity score matching considerably improved the balance of the potential confounders between cannabis non-users and users. In a matched sample, non-medical cannabis use was associated with increased risks of prescription opioid misuse (OR = 3.15, 95%CI: 2.89-3.44) and use disorder (OR = 2.52, 95%CI: 2.06-3.10). Cannabis dual use and medical cannabis use were associated with increased risks of prescription opioid misuse (OR = 2.55, 95%CI: 1.78-3.65; OR = 2.15, 95%CI: 1.58-2.91, respectively), but they were not associated with prescription opioid use disorder.

Discussion and conclusions

Medical and non-medical cannabis use both were both associated with increased risks of prescription opioid misuse. Medical cannabis use, however, was not associated with prescription opioid use disorder, and non-medical cannabis was. There appeared to be differential associations between cannabis use and prescription opioid use disorder by cannabis use purpose.