Effect Size and NNT of the Dextroamphetamine Transdermal System (d-ATS) for ADHD in Children and Adolescents: Post-Hoc Analysis of a Pivotal Study

Abstract: Background: In a pivotal study, the dextroamphetamine transdermal system (d-ATS) met primary and secondary efficacy endpoints for ADHD in children and adolescents. This post-hoc analysis investigated effect size and number needed to treat (NNT) for d-ATS. Methods: After a 5-week, open-label dose-optimization period (DOP) and 2-week double-blind period (DBP), ADHD-RS-IV and Clinical Global Impression–Improvement scale (CGI-I) were assessed. Least-squares means, 95% confidence intervals (CIs), and P-values were calculated from a linear mixed model including ADHD-RS-IV scores for each time point, sequence and treatment as fixed effects, and subject as a random effect. Effect sizes for change in ADHD-RS-IV score from baseline were calculated as the difference in least-squares mean score between treatment arms divided by root square error from the model. Responder analysis of CGI-I used McNemar’s test for paired samples. NNT was inverse of the difference in proportions between treatment groups. Results: The DOP included 110 patients, with 106 randomized in the DBP. Differences (d-ATS–placebo) in least-squares mean (CI) during the DBP were ADHD-RS-IV total score, -13.1 (-16.2, -10.0); inattention subscale, -7.3 (-9.0, -5.6); and hyperactivity-impulsivity subscale, -5.8 (-7.6, -4.2) (Nf106; PShort Description: In this post-hoc analysis of a pivotal study of dextroamphetamine transdermal system (d-ATS) for ADHD in children/adolescents, significant improvements vs placebo in ADHD-RS-IV scores were observed; number needed to treat for remission/improvement was 3. Investigator-observed response occurred in 86% of d-ATS–treated patients vs 24% of placebo-treated patients. These results indicate that d-ATS was effective in treating ADHD in children and adolescents and comparable to oral d-amphetamine preparations, with a similar effect size and NNT.Name of Sponsoring Organization(s): Noven Pharmaceuticals, Inc.