Secular Trends in Hazardous Alcohol and Cannabis Use from 2015 to 2024 in Diverse Subgroups of Youth Entering Residential Care

<b><i>Background</i></b>: Secular trends in adolescent alcohol and cannabis use in the general population have shown declines in both substances, but trends among high-risk youth placed in residential care are unclear. Understanding these differences could help address substance-related issues in this vulnerable population. <b><i>Objectives</i></b>: This study examines subgroup differences in the secular trends in hazardous alcohol and cannabis use and co-use among youth entering residential care using clinical records data collected over a 10-year period from 2015 to 2024. Repeated cross-sectional data from 2,256 youth (ages 9-18 years) entering a Midwestern U.S. residential care facility (2015-2024) were analyzed. Hazardous alcohol and cannabis use were assessed using the AUDIT (Alcohol Use Disorders Identification Test) and CUDIT-R (Cannabis Use Disorders Identification Test-Revised), respectively. Subgroup differences were examined through product-term logistic regressions, testing trends by age, sex, and race/ethnicity. <b><i>Results</i></b>: Hazardous alcohol use significantly increased over time among females (OR = 1.043, se = 0.026, <i>p</i> < 0.05) but decreased among males (OR = 0.981, se = 0.021, <i>p</i> < 0.05). Both Latinx youth (OR = 0.944, se = 0.038, <i>p</i> < 0.05) and American Indian youth (OR = 0.909, se = 0.066, <i>p</i> < 0.05) reported a significant decrease in hazardous alcohol use over time compared to a significant increase among White youth (OR = 1.021, se = 0.018, <i>p</i> < 0.05). A similar interaction pattern was shown for American Indian compared to White youth for comorbid use. <b><i>Conclusions</i></b>: Results have implications for ongoing monitoring and development of tailored interventions for youth entering residential care.