Co–administering cannabis with tobacco and persistent tobacco smoking after 4½ years in young adults who use stimulants: A prospective population–based study

ABSTRACT

Tobacco smoking remains highly prevalent in high-risk groups, including young adults who use cannabis and a variety of other drugs. We examine whether co-administering cannabis with tobacco is associated with heavier and more persistent tobacco smoking compared to separate use of these substances among young adults who use drugs recreationally. Data are from a prospective population-based study of young adults residing in Queensland, Australia, who recurrently used ecstasy or methamphetamine. The mean age was 20.8 years at baseline, and 47% were female. An ordinal regression model was developed (n = 277) with levels of tobacco smoking at 4½ years as the outcome. At baseline, just under half the sample (44.6%) had not co-administered cannabis with tobacco in the last month, 9.5% rarely co-administered, 7.7% sometimes co-administered, and 38.2% always co-administered. Always co-administering cannabis with tobacco was associated with more frequent and persistent tobacco smoking at 4½ years (Odds Ratio (OR): 1.98, 95% Confidence Interval (CI): 1.02, 3.83), independently of factors including baseline frequency of cannabis and tobacco use. Young adults who use cannabis should be advised not to co-administrate cannabis with tobacco, and comprise an important target group for tobacco smoking cessation interventions.

KEYWORDS:

• Cannabis use
• tobacco use
• co-administration
• young adults

Acknowledgments

The authors thank the study participants, interviewers, and project staff. We also thank Idin Panahi for his comments on the drafts.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Contribution

All authors contributed to the study design and conception. Abdullah conducted the data analysis and drafted the manuscript, with contributions from Andrew Smirnov and Coral Gartner. All authors contributed to manuscript revisions and have approved the final manuscript.

Additional information

Funding

This research was supported by an Australian Research Council’s Linkage Projects grant [LP0776879]. Abdullah Alghamdi was supported by a scholarship from Umm Al-Qura University, Saudi Arabia.