New risk indexes for identifying children at risk of high-risk substance use during adolescence

Aim: Develop brief, practical risk indexes for identifying children with no/minimal history of substance use who are at risk of high-risk substance use patterns during adolescence.Design: Observational, longitudinal cohort study (ABCD Study).Setting: 21 study sites across the United States.Participants: Community-based sample of 8,055 youth recruited at ages 9-10 years old (49% female, 20% Hispanic; 15% Black).Measurements: To create the risk indexes, we drew items from a comprehensive baseline assessment when youth were 9-10 years old that measured all major risk factors for adolescent substance use. We then measured substance use outcomes at annual follow-up assessments occurring annually through age 15-16 years old. We used a training subsample (n=5,555) to choose which items should be on the risk indexes and fit a risk algorithm, then evaluated the predictive performance of each risk score in holdout data (n=2,500).Findings: The parent- and youth-report risk indexes were 8 items long, each asking questions about multiple risk factors for future substance use. The risk score based on parent report at ages 9-10 predicted several clinically meaningful outcomes during early-to-mid adolescence: being treated for a substance use problem (AUC=0.84), meeting DSM 5 criteria for a substance use disorder (AUC=0.68), experiencing multiple negative consequences of use (AUC=0.64) and establishing monthly use before one’s 15th birthday (AUC=0.68) (ps<.001). Children in the top 10% of the parent-report risk score were 2.1-3.1x times more likely than the base rates to go on to display high-risk substance use outcomes during adolescence. The risk scores significantly predicted alcohol, cannabis, and nicotine use outcomes, in addition to general substance use. Risk scores based on youth report were also significant predictors of substance use outcomes, but their performance was weaker (mean AUC=0.65, vs. 0.68 for parent report).Conclusions: 8-item parent- and youth-reported risk indexes a identify children at markedly elevated risk of clinically concerning substance use outcomes. These risk indexes compare favorably with existing tools and might prove useful for triage, monitoring, or targeted prevention. The next step is to perform external validations in new samples.