Trends in cannabis and tobacco co-use in the United States, 2002-2021.

Background: Co-use of cannabis and tobacco poses greater risks than use of either substance individually and may be becoming more prevalent with increasing cannabis medicalization and legalization. We aimed to assess trends in the prevalence of cannabis and tobacco co-use between 2002-2019 and identify the updated prevalence and correlates of co-use in 2021 among US adults.

Methods: This study used data from the 2002-2021 National Survey on Drug Use and Health, a nationally-representative, cross-sectional survey in the US. We assessed prevalence trends in past 30-day cannabis and tobacco co-use, exclusive cannabis use, and exclusive tobacco use overall and by sociodemographic group using joinpoint regression. Additionally, multinomial models identified correlates of co-use in 2021.

Results: In 2021, the weighted prevalence of cannabis and tobacco co-use was 6.38 %, the weighted prevalence of exclusive cannabis use was 7.28 %, and the weighted prevalence of exclusive tobacco use was 15.01 %. From 2002 to 2019, the prevalence of past 30-day co-use of cannabis and tobacco increased significantly (annual percentage change [APC]: 1.9 [1.4-2.4], P<0.05) among the overall US population. All subgroups of sex, race/ethnicity, and age also saw significant increases in co-use, other than young adults ages 18-25, for whom co-use was stagnant between 2002-2014 and then decreased significantly between 2014-2019.

Conclusion: This study identified increasing cannabis and tobacco co-use overall and among most sociodemographic strata in the US. As cannabis policy changes rapidly, co-use requires closer surveillance, clinical screening, and dedicated research.