Quinn PD, Fine KL, Rickert ME, et al. - In a nationwide Swedish cohort, researchers sought to investigate the correlation of opioid initiation among adolescents and young adults with subsequent broadly defined substance-related morbidity. Population-register data were analyzed from January 1, 2007, to December 31, 2013, on Swedish people aged 13 to 29 years by January 1, 2013, who were naive to opioid prescription. Among the included cohort (n = 1,541,862; 793,933 male [51.5%]), 193,922 people started opioid therapy by December 31, 2013 (median age at initiation, 20.9 years [interquartile range, 18.2-23.6 years]). Among adolescents and young adults studied in this analysis, the initial opioid prescription receipt was correlated with an almost 30% to 40% relative increase in the risk of subsequent substance-related morbidity in multiple confounding-adjusted designs. Such results indicate that this rise could be lower than previously estimated in some other studies.