Post hoc analyses of response rates to pharmacological treatments in children and adolescents with attention-deficit/hyperactivity disorder

Introduction and objectives: Lack of consensus regarding how best to define treatment response hinders translation from trials to the clinic. These post hoc analyses examine three commonly used response criteria in six trials of lisdexamfetamine dimesylate (LDX) in children and adolescents with attention-deficit/hyperactivity disorder (ADHD).

Methods: Data from four short-term randomised controlled trials (RCTs) and two long-term open-label studies were analysed. Children and adolescents with ADHD received either dose-optimised (30-70 mg/day) or fixed-dose (70 mg/day) LDX. The RCTs included osmotic-release oral system methylphenidate (OROS-MPH) or atomoxetine (ATX) as a head-to-head comparator or as a reference treatment. Three definitions of response were used in these analyses: reductions of ⩾30% or ⩾50% in ADHD Rating Scale IV (ADHD-RS-IV) total score plus a Clinical Global Impressions - Improvement (CGI-I) score of 1 or 2, or an ADHD-RS-IV total score of ⩽18.

Results: At the end point, LDX response rates for the least stringent criterion of ⩾30% reduction in ADHD-RS-IV total score plus a CGI-I score of 1 or 2 ranged from 69.6% to 82.6%. The proportion achieving the more stringent criterion of a reduction in ADHD-RS-IV total score of ⩾50% plus a CGI-I score of 1 or 2 at the end point ranged from 59.8% to 74.8%. An ADHD-RS-IV total score of ⩽18 at the end point was achieved by 56.7-79.9% of participants. Response rates remained stable throughout the long-term open-label studies.

Conclusions: Response rates were similar for the two more stringent response criteria. The less stringent criterion resulted in higher response rates and may include partial responders.