Atomoxetine Effect on ADHD Scrutinized in Meta-analysis

Atomoxetine was better than comparators in improving symptoms of ADHD.

In a new comprehensive meta-analysis, investigators reported atomoxetine (Strattera/Lilly) was superior to comparators overall in controlled studies and comparable to active medication controls in improving parent-rated core symptoms of attention-deficit/hyperactivity (ADHD).

"The present review includes a sample of studies with greater than 50% of additional total investigations — many of which are not represented in any of the formerly conducted reviews," said Matthew Mychailyszyn, PhD and Jessica Gayleard, Department of Psychology, Towson University, Towson, Maryland.

The current meta-analysis included 42 studies published between 2001 and 2014 involving 8,398 children with ADHD ranging from 5 to 18 years and the study lasted three to 24 weeks.

The investigators highlighted a previous review that found initial improvement of symptoms with atomoxetine were measurable at one week, with some continued improvement in weeks two through six. Another review showed that the efficacy of the medication was still increasing at weeks six through eight.

"Twenty-four weeks were therefore decided upon for this present meta-analysis as it reflects just under half of a year — ample enough time to allow subjects to have been on the non-stimulant – and allows the most comprehensive inclusion of study evaluation results," explained Mychailyszyn and Gayleard.

Their meta-analysis utilized a standardized mean gain (SMG) to assess treatment effect on symptoms over time. The investigators distinguished this approach from standardized mean difference (SMD), which compares scores between groups at a single time point. Applying SMG allowed researchers to determine whether an intervention group yields statistically significantly greater change in scores over time compared to a control group, according to Mychailyszyn and Gayleard.

In the 11 studies, which used active medication controls, the mean SMG effect size for atomoxetine was 1.55, and 1.56 in control groups. When atomoxetine was compared with placebo, the mean SMG of 1.18 with atomoxetine was statistically significantly greater than the 0.85 with placebo.

The comparable effects of atomoxetine and psychostimulants in improving core symptomatology of ADHD, which was superior to that of placebo, were not affected by factoring in study durations.

Mychailyszyn and Gayleard believed atomoxetine to be comparable to psychostimulants in effectiveness, safety, and tolerability, and suggested that the meta-analysis confirmed it could be a viable treatment option. They noted that patients could react differently to different forms of treatment, though atomoxetine may be particularly valuable as an alternative following inadequate response to, or poor tolerance of a psychostimulant.

The meta-analysis of atomoxetine treatment studies, “Atomoxetine Treatment for Children and Adolescents with Attention-Deficit/Hyperactivity Disorder (ADHD): A Comprehensive Meta-analysis of Outcomes on Parent-Rated Core Symptomatology,” was published on-line January 21 in ADHD Attention Deficit and Hyperactivity Disorders.

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