ScholarWorks@Georgia State University

Tobacco use remains the leading cause of preventable death in the United States (US). Overall, tobacco use in the US steadily declined among youth and young adults since the mid- 1970s. During the 2000s, that progress reversed as new products such as e-cigarettes flooded the US market. E-cigarettes are particularly appealing to youth and young adults due – in part – to the availability of product flavors. In addition, the increased legalization of marijuana has been associated with increased co-use of tobacco and cannabis among youth. The unprecedented changes to the nicotine, tobacco, and marijuana (NTM) product landscape in the last decade created the potential for increased and increasingly complex patterns of NTM use as well as negative health consequences among populations known to be at greater risk for NTM use like the lesbian, gay, bisexual, and transgender (LGBT) community, youth, and young adults. Using cross-sectional data from seven states between February 2020 and June 2022, this dissertation assessed NTM use among 13-24 year olds. Specifically, the study examined the empirically identified, dominant, and distinct polyuse patterns – or classes – of NTM products that capture individual variability and population heterogeneity among youth and young adults in the US; the effect of LGBT identity and measurement bias on class membership; and the effect of intersectionality of LGBT identity and gender in the context of race/ethnicity and age on class membership. The study found nine distinct classes of NTM polyuse, ranging from regular use categories dominated by e-cigarettes and marijuana products to ever/irregular use of various NTM products. Based on proportions of class membership, LGBT respondents comprised greater proportions of classes characterized by regular NTM use. Analyses also suggested that LGBT identity was a source of differential item functioning (DIF) – measurement noninvariance – for certain latent indicators of NTM polyuse use, particularly marijuana. Differences in NTM use were also observed by gender among LGBT respondents. Membership for female LGBT respondents was higher among classes characterized by more regular marijuana use; although, male LGBT respondents tended to have increased membership in regular NTM use classes. In general, LGBT respondents had greater membership in the regular NTM use classes than non- LGBT respondents. Notable differences in class membership by race/ethnicity and age were also found. For race/ethnicity, the most prominent differences tended to be in the characterization of e-cigarette and marijuana co-use. For age, the 13-17 year old respondents NTM use was primarily in classes with distinct e-cigarette use; the 18-24 year old users had greater membership in classes with current marijuana use. The nature and number of classes along with the impact of LGBT identity, gender, race/ethnicity, and age on class membership provided unique insight into emerging patterns of NTM polyuse that are important for public health action and future regulation of NTM products. The methodological contributions from examining the impact effect of DIF among the LGBT population can be translated to improvements in surveys, measures, and analyses that offer richer understanding of this important population. In addition, this dissertation adds that, as NTM products and regulations diversify, research needs to explicitly address population heterogeneity to develop policy, practices, and interventions that fully protect the public’s health.