title: Concurrent polysubstance use in a longitudinal study of US youth: associations with sexual orientation.
abstract: To estimate longitudinal associations between self-reported sexual orientation and past-year polysubstance use among youth, and test how gender, age and early onset of tobacco and alcohol use contributed to variation in polysubstance use.
  
  
  
  Longitudinal community-based cohort of US adolescents from the Growing Up Today Study (GUTS 1) (n = 16 873) followed from ages 12-29 years.
  
  
  
  United States of America.
  
  
  
  A total of 13 519 individuals (7839 females; 5680 males) who responded to at least one of five self-administered questionnaires from 1999 to 2010. Ninety-three per cent reported their race/ethnicity as non-Hispanic white.
  
  
  
  Multivariable repeated measures generalized estimating equations estimated relative risks (RRs) of concurrent polysubstance use (i.e. past 12-month use of three or more substances) comparing sexual orientation minority youth [i.e. mostly heterosexual (MH), bisexual (BI), gay/lesbian (GL)] to their same-gender, completely heterosexual (CH) counterparts. Mediation analyses tested whether early onset of tobacco and/or alcohol use explained relationships between sexual orientation and concurrent polysubstance use.
  
  
  
  Compared with their same-gender CH peers, sexual minorities evidenced higher risk for concurrent polysubstance use over all repeated measures [risk ratios (RRs) for sexual minority subgroups: from 1.63-2.91, P-values: <0.001] and for all age groups (RRs: from 1.50-4.04, P-values: < 0.05-< 0.001), except GL males aged 18-20 years. Differences between sexual minorities and CHs were larger among females than males (P-values for sexual orientation × gender interactions were < 0.05 for MHs and BIs), and among younger versus older ages (P-values for sexual orientation × age interactions were < 0.05, except for BI males). Sexual minorities' younger age of smoking and/or drinking initiation contributed to their elevated polysubstance use (% of effect explained was between 9.4-24.3, P-values: 0.04-< 0.001), except among GL males.
  
  
  
  Sexual minority youth in the United States, and in particular younger females, appear to be at disproportionate risk for concurrent past-year polysubstance use. Early onset of smoking and drinking may contribute to elevated risk of polysubstance use among sexual minorities.
authors: Department of Public Health, William Paterson University New Jersey, Wayne, NJ, USA.
authors: Aleksandar
authors: A
authors: Kecojevic
authors: Graduate School of Public Health, Division of Health Promotion and Behavioral Science, San Diego State University, San Diego, CA, USA.
authors: Hee-Jin
authors: HJ
authors: Jun
authors: Division of General Pediatrics, Boston Children's Hospital/Harvard Medical School, Boston, MA, USA.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Fenway Health, The Fenway Institute, Boston, MA, USA.
authors: Sari L
authors: SL
authors: Reisner
authors: Graduate School of Public Health, Division of Health Promotion and Behavioral Science, San Diego State University, San Diego, CA, USA.|Channing Division of Network Medicine, Brigham and Women's Hospital, Boston, MA, USA.
authors: Heather L
authors: HL
authors: Corliss
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000428:Alcohol Drinking / Q000453:epidemiology; D001727:Bisexuality; D016022:Case-Control Studies; D002648:Child; D005260:Female; D020010:Heterosexuality; D006716:Homosexuality; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D016017:Odds Ratio; D012737:Sex Factors; D012725:Sexual Behavior / Q000706:statistics & numerical data; D000072339:Sexual and Gender Minorities / Q000706:statistics & numerical data*; D012907:Smoking / Q000453:epidemiology*; D019966:Substance-Related Disorders / Q000453:epidemiology*; D000066608:Underage Drinking / Q000706:statistics & numerical data*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: Adolescents; early onset of substance use; emerging adults; longitudinal study; polysubstance use; sexual orientation