A socioeconomic gradient in health – the association of low economic means with a higher likelihood of worse health – is well documented in the extant literature (Adler et al., 1994, Angell, 1993). The social gradient has been consistently shown in epidemiology and social science research despite measurement complexities and substantial variation in factors like race/ethnicity, age, sex, geographic location, and specific health outcomes(Petrovic et al., 2018, Schieman and Koltai, 2017). Determining the contours of the socioeconomic gradient involves assessing differences in socioeconomic status (SES) according to reliable measures of education, income, and wealth(Galobardes et al., 2007). Adolescent SES is commonly assessed through composite indices involving family material possessions, cultural capital, parental education, and parental employment and occupation(Moreno-Maldonado et al., 2018). Generally, the literature shows that low SES negatively impacts an individual's biopsychology and can have detrimental effects on health and longevity throughout the life course(Kraft & Kraft, 2021).

In the United States and beyond, low SES has been associated with a higher prevalence of certain health risk behaviors, including cigarette smoking(Garrett et al., 2019, Casetta et al., 2017, Fidler et al., 2008). Research has shown that low SES is associated with smoking uptake, lower cessation rates, and a higher likelihood of using other combustible tobacco products(Hiscock et al., 2012, Hiscock et al., 2015, Spears et al., 2019). In addition, low SES smokers are more likely to access smoking-friendly environments(Jahnel et al., 2018). Despite the well-established evidence supporting a socioeconomic gradient in smoking, there is little evidence about if and to what extent a socioeconomic gradient is apparent in e-cigarette use, particularly among youth. E-cigarette use has become a major public health concern as prevalence is especially high among adolescents and young people(Cooper, 2022). There is strong evidence that flavored e-cigarettes are particularly attractive to and widely used by adolescents and young adults(Goldenson et al., 2019, Hong et al., 2019, Kong et al., 2015, Zhu et al., 2014). Moreover, one population disproportionately using e-cigarettes is sexual minority youth(Azagba et al., 2019, Azagba and Shan, 2021b, Garcia et al., 2021), and SES has been shown as an important determinant of health among this group(Spiker, 2020). E-cigarette use presents many potential health dangers, including cognitive risks due to nicotine addiction and respiratory hazards due to inhaling aerosolized liquid toxicants and other chemicals (Chun et al., 2017, McConnell et al., 2017).

The few studies that have examined the association between SES and e-cigarette use among the general youth population have found mixed results. Several studies showed the socioeconomic gradient in e-cigarette use among youth(Babineau et al., 2015, Khoury et al., 2016, Kinnunen et al., 2016, Simon et al., 2017, Wills et al., 2017), while others found no significant association between SES and e-cigarette use among youth(Barrington-Trimis et al., 2015, Moore et al., 2015, Pentz et al., 2015). One study even found that high SES was associated with greater youth e-cigarette use(Rennie et al., 2016). It is unclear to what extent the inconclusive findings are due to the imbalance between the different SES groups in terms of observed characteristics. This study examines the association between SES and youth e-cigarette use and addresses potential confounding factors through the propensity score weighting approach. Another unique feature of this study is exploring SES and e-cigarette use among sexual minority youth.

We hypothesized that low SES sexual minorities would be more likely to use e-cigarettes than other SES sexual minority groups and all SES non-sexual minority groups. As the minority stress model posits, marginalized groups experience unique and excess social stressors that make them more vulnerable to health disparities(Hatzenbuehler et al., 2013, Meyer, 2003). There is evidence that sexual minority adults and youth are more likely than their heterosexual counterparts to use tobacco and e-cigarettes(Caputi, 2018, Garcia et al., 2021). Furthermore, low-SES sexual minorities may be more engaged in risky health behaviors than high-SES sexual minorities and may also be confronted with residential environments that are hostile to their identities, stricter standards for gender role conformity, and isolation from the mainstream sexual minority community(McGarrity, 2014). Low SES sexual minorities may face even greater stress, stigma, and discrimination than high SES sexual minorities(McGarrity, 2014), and minority stress processes may operate differently for lower SES versus higher SES sexual minorities(Shangani et al., 2020). Additionally, previous studies have observed interactive effects of SES and sexual minority status on tobacco use(Amroussia et al., 2020, Hart et al., 2020). These lines of thought informed our hypothesis.