Integrating Use Frequency, Vaping, and Dependence to Characterize Nicotine-Cannabis Co-Use in Young Adults: A Latent Class Analysis.

INTRODUCTION: Tobacco and cannabis co-use is an increasingly complex public health challenge shaped by rapid expansion of vaping technologies and product diversity. To inform prevention and intervention efforts, behavioral typologies that incorporate use frequency, vaping, dependence/disordered use indicators are needed. METHODS: We analyzed pooled 2022-2023 National Survey on Drug Use and Health data from 14,500 U.S. young adults aged 18-29 who reported tobacco/nicotine or cannabis use. Latent class analysis identified subgroups based on past 30-day tobacco use frequency, nicotine vaping frequency, cannabis use frequency, nicotine dependence (Nicotine Dependence Syndrome Scale), and cannabis use disorder (DSM-5 criteria). RESULTS: A four-class model optimally balanced fit and interpretability. The largest subgroup was the nicotine-dominant use class (38.6%), marked by high tobacco use and minimal cannabis involvement. Three distinct co-use classes were identified: low co-use (17.4%), characterized by the lowest levels of tobacco product use, nicotine vaping, and cannabis use and comparatively low nicotine dependence and cannabis use disorder; cannabis-dominant co-use (32.3%), characterized by near-daily cannabis use with relatively low tobacco product use, nicotine vaping, and nicotine dependence; and high-frequency co-use (11.7%), characterized by frequent use of both nicotine products and cannabis and elevated nicotine dependence and cannabis use disorder. Serious psychological distress was associated with nearly twice the risk of cannabis-dominant co-use relative to nicotine-dominant use. CONCLUSION: Incorporating use frequency, vaping behaviors, and validated dependence and disordered use measures revealed distinct, tobacco-cannabis co-use behavioral phenotypes among young adults. Findings underscore the need for integrated prevention and cessation approaches tailored to heterogeneous co-use patterns.