Increasing cannabis use is associated with poorer cigarette smoking cessation outcomes: Findings from the ITC Four Country Smoking and Vaping Surveys, 2016-2018
Driezen, P., Gravely, S., Wadsworth, E., Smith, D.M., Loewen, R., Hammond, D., Li, L., Abramovici, H., McNeill, A., Borland, R., Cummings, K.M., Thompson, M.E., Fong, G.T. (2021). Increasing cannabis use is associated with poorer cigarette smoking cessation outcomes: Findings from the ITC Four Country Smoking and Vaping Surveys, 2016-2018. Nicotine and Tobacco Research, [Published online June 10, doi: 10.1093/ntr/ntab122].
Introduction: Concurrent use (co-use) of tobacco and cannabis may impede successful cigarette smoking cessation. This study examined whether changes in cannabis use frequency were associated with smoking cessation.
Methods: Nationally representative samples of adult cigarette smokers from Canada (n=1455), the United States (n=892), England (n=1416), and Australia (n=717) were surveyed in 2016 and 2018. In each year, smokers reported how often they used cannabis in the previous 12 months. Reports were compared to determine whether cannabis use increased, remained unchanged, or decreased. Smoking cessation outcomes, measured in 2018, were (1) any attempt to quit in the previous year, (2) currently quit, and (3) currently quit for at least 6 months. Weighted multivariable logistic regression estimated the association between changes in cannabis use and cessation outcomes.
Results: Cigarette smokers who increased their frequency of cannabis use were significantly less likely to be currently quit than non-cannabis using smokers (adjusted odds ratio (aOR) = 0.52, 95% CI: 0.31, 0.86); they were also less likely to have quit for at least 6 months (aOR = 0.30; 95% CI: 0.15, 0.62).
Conclusions: Smokers who increase their frequency of cannabis use have poorer smoking cessation outcomes compared to non-cannabis using smokers. It will be important to monitor the impact of cannabis legalization on patterns of cannabis use, and whether this influences cigarette smoking cessation rates.