Age, period, and cohort effects in synthetic cannabinoid use among US adolescents, 2011-2015

Background: Synthetic cannabinoids use has been a public health concern given association with hospitalization and death among users. While national reports estimate that reported use is declining among adolescents, differences by birth cohort may indicate subgroups who remain at higher risk, both in the overall adolescent population and among demographic subgroups. Methods: We estimated age, period, and cohort models of self-reported past-year synthetic cannabinoid use (queried as synthetic marijuana [KC, Spice]) among 54,865 adolescents aged 13-19 attending high school from 2011 to 2015. Results: Past-year use decreased from 11.86% in 2011 to 4.75% in 2015. This decrease was best represented as a linear downward trend. When stratified by key covariates, however, results indicated evidence of a positive cohort effect for students of higher socioeconomic status (SES). For those students, use did not decrease at the same rate as the overall population; younger cohorts of high SES students remain at higher risk for synthetic cannabinoid use than older cohorts as well as lower SES peers. A similar and stronger association was found for frequent marijuana users (>= 20 occasions of past-year use). Multi-level models indicated that groups at highest risk included older adolescents, Hispanics and other/mixed race students, cigarette users, and frequent marijuana users. Conclusion: Synthetic cannabinoid use is associated with morbidity as well as mortality; continued attention to reducing synthetic cannabinoid use remains an important public health priority to maximizing student health. (C) 2016 Elsevier Ireland Ltd. All rights reserved.