We calculated the ORs to estimate the effect size of the association between medication status (medicated vs nonmedicated) and 2 separate dichotomous substance outcomes: (1) ever use (yes/no) and (2) abuse or dependence (yes/no). When any cell used to calculate the OR had a value of 0, we inserted 0.5 to all 4 cells to calculate the effect size according to expert recommendation.21 An OR of 1 indicated that substance outcome was equivalent in children with and without medication treatment history, whereas an OR greater than 1 or less than 1 indicated that the outcome in the medicated group was more or less likely, respectively, to occur in the medicated group. The 95% CI for the OR represents the relative precision of the measurement (ie, wider ranges are less precise). For each study, an OR was separately calculated for each available substance outcome. Thus, the same study could yield as many as 10 ORs, reflecting 5 substance types and use and abuse or dependence. When there was no positive endorsement for the substance outcome, the study was excluded for that
