Underexplored Heterogeneity and Publication Bias for the Electronic Cigarette and Marijuana Use Association

To the Editor We read with great interest the systematic review and meta-analysis by Chadi et al,¹ who examined the association between electronic cigarette (e-cigarette) and marijuana use in adolescents and young adults, and they found that past or current e-cigarette users are more likely to be subsequent marijuana users. This finding signifies the importance of quitting e-cigarettes to curb the increasing use of marijuana among young people.