Substance use among sexual minorities in the US - Linked to inequalities and unmet need for mental health treatment? Results from the National Survey on Drug Use and Health (NSDUH)

Background: Sexual minorities (SM) have specific substance use patterns and show elevated rates of substance use and substance use disorders. We investigated the potential association between substance use - including chemsex drug use - among SM adults in the United States (US) and social inequality, with an additional focus on disparities in unmet need for mental health treatment.Methods: A secondary cross-sectional data analysis was performed using National Survey on Drug Use and Health (NSDUH) data from 2015 to 2017 and including 126,463 individuals with 8241 identifying as SM. Multivariable logistic regression models were implemented to quantify disparities in substance use, to calculate the effect of sociodemographic variables on substance use, and to examine associations with socioeconomic vulnerability.Findings: SM showed higher odds of past-year substance use and lifetime chemsex drug use. All SM except for bisexual men exhibited higher odds of past-month binge drinking relative to heterosexuals. Bisexual women had higher odds for use of all analysed substances relative to heterosexual women. Being older and being a woman were shown to be protective factors. Urbanity, being uninsured, and unmet need for mental health treatment were associated with significantly higher odds of substance use, chemsex drug use and binge drinking. A link was established between drug use and health indicators, with higher odds of drug use for lower health ratings. SM experienced significantly higher levels of socioeconomic vulnerability. Higher vulnerability indices were associated with increased odds for drug use.Interpretation: This study is among the first nationally representative samples that analysed the link between sociodemographic factors and unmet need for mental health treatment and substance use in SM. It emphasises the multifactorial aetiology of substance use exposure, highlights the underlying mechanisms for substance use among SM while underscoring disparities among them. Approaches tailored to SM subgroups may be needed to address comorbidities and negative health outcomes of substance use in the long-term. However, critical gaps in the literature remain and large-scale studies inclusive of SM individuals are needed to present causal links.