Osmotic-release methylphenidate randomized controlled trial for adolescents with attention-deficit/hyperactivity disorders and substance use disorders: A missing data sensitivity analysis.

The purpose of this study was to examine sensitivity to missing data procedures on treatment effects in a randomized controlled trial (RCT) of osmotic-release methylphenidate (OROS) for adolescents with co-occurring attention-deficit/hyperactivity disorder (ADHD) and substance use disorders (SUD). Data came from a National Drug Abuse Treatment Clinical Trials Network study (CTN-0028, N=303), which evaluated the safety/efficacy of a 16-week RCT of OROS vs. placebo in adolescents aged 13-18 with ADHD who were also receiving cognitive-behavioral therapy for their SUD. The two primary outcomes were clinician-reported ADHD symptoms and self-reported past 28 days of substance use (SU). A parallel grow model was used to assess the effect sizes assuming missing at random (MAR) compared to two missing not at random (MNAR) models: Diggle-Kenward (DK) selection model and Wu-Carroll (WC) selection model.

The MAR model found no significant treatment effect on ADHD or SU, and the effect sizes were small for both ADHD and SU. The MNAR DK model also produced non-significant treatment effects with similar effect sizes of ADHD and SU. The MNAR WC model evidenced a significant effect of OROS relative to placebo on SU, and the effect sizes for both ADHD and SU were larger than reported in the other models.

Conclusions: While the MAR model and one MNAR model found similarly sized effects as the original RCT, the second MNAR model produced different results for both of the outcomes. This sensitivity analysis highlights an important need for future RCTs of co-morbid mental illness and SUDs to carefully evaluate the missing data assumptions made when assessing treatment effects.

Related protocols: CTN-0028