Sensitivity analyses were conducted for the 4 outcomes with significant heterogeneity in effects using the leave-one-out approach (ie, running the random-effects model after the removal of each individual study). No single study unduly influenced the OR estimates of the association between stimulant medication treatment and alcohol abuse or dependence (pooled OR estimates, 0.70–0.96; all 95% CIs included 1). For marijuana abuse or dependence, pooled OR estimates ranged from 0.96 to 1.23, and all 95% CIs included 1. The effect size was no longer heterogeneous (P >.05) after the individual removal of 3 studies.27,32,35 For nicotine use, after the removal of Huss,32 the effect sizes were no longer significantly heterogeneous (Q = 4.29, P =.12). This study may have contributed to heterogeneity given that the overall estimate from the meta-analysis (Q = 1.55) was not included in the CI range from Huss.32 Sensitivity analysis for nonspecific drug abuse or dependence found pooled OR estimates ranged from 0.76 to 1.01, and all 95% CIs included 1. The effect sizes were no longer heterogeneous (P >.05) after the removal of one study.36 When
