Tobacco-cannabis co-use and risk of substance use problems among Black and Hispanic adolescent and young adult females in New York City.

Background: Tobacco-cannabis co-use is more common than exclusive cannabis use, and is linked to more severe tobacco and cannabis health consequences. We assessed trends and predictors of tobacco-cannabis co-use and their link to future substance use problems and severity among Black and Hispanic adolescent and young adult (AYA) females living in New York City. Methods: Secondary data were analyzed from a seven year (2013-2020) prospective open cohort study conducted at Mount Sinai Adolescent Health Center in New York City (n=1,281). Participants completed questionnaires every six months, and self-reported information on use of smoked tobacco, cannabis, and blunts/spliffs; sexual risk behaviors, depressive symptoms, and other substance use. Regression analyses examined initiation and frequency of past 30-day co-use, and risk of future substance use severity. Results: Age-adjusted prevalence of past 30-day cannabis use increased from 46.5% in 2013-2014 to 59.0% in 2019-2020, while past 30-day tobacco smoking declined from 22.1% to 6.1%. After accounting for blunt/spliff use, any use of tobacco increased from 31.6% in 2013-2014 to 39.6% in 2019-2020. Co-consumers were more likely to meet criteria for clinical depression (OR=1.34, 95%CI:1.12-1.61) and have same-sex (OR=1.35, 95%CI:1.03-1.76) and/or multiple male sex partners (OR=1.45, 95%CI:1.23-1.71). Those who used blunts/spliffs frequently or rarely had higher risk profiles for problematic substance use. Conclusions: Tobacco-cannabis co-use, particularly blunt use, appears to drive increasing prevalence of cannabis use, sustain overall rates of tobacco use, and predicts substance use problems among inner-city Black and Hispanic AYA females, independent of other factors.