Shire announced the results of a study which suggested that stimulant medications such as ADDERALL XR® (mixed salts of a single-entity amphetamine product) are significantly more effective than non-stimulant medications in the treatment of patients aged 8 to 15 with Attention-Deficit/Hyperactivity Disorder (ADHD).

The study, a meta-analysis of 29 double-blind, placebo-controlled treatment studies undertaken over the past 25 years and involving nearly 4,500 children with ADHD, was presented at the U.S. Psychiatric & Mental Health Congress in New Orleans.

"The results of the meta-analysis, along with their own clinical experience, may help physicians draw conclusions about an ADHD medication's relative effectiveness in the absence of direct head-to-head comparisons among leading prescription ADHD medications," said Stephen V. Faraone, Ph.D., lead researcher and director of child and adolescent psychiatry at State University of New York Upstate Medical University. "By studying the magnitude of different drug effects on ADHD in children, my colleagues and I found that stimulant ADHD medications produced larger effect sizes than nonstimulants, suggesting that amphetamine- and methylphenidate-based stimulants are more effective treatments for ADHD symptoms."

About the Study

The meta-analysis reviewed data from 29 randomized, double-blind, placebo-controlled treatment studies lasting for two or more weeks published after 1979. Subjects included 4,465 children with ADHD, aged 8 to 15 years. ADHD was defined using criteria from the Diagnostic and Statistical Manual of Mental Disorders®, Fourth Edition, a publication of the American Psychiatric Association.

The trials in this meta-analysis studied 15 medications using 17 different outcome measures of ADHD symptoms, including "hyperactive," "inattentive," "impulsive" or "oppositional behavior." The most commonly identified medications were amphetamine and methylphenidate compounds. Non-stimulant medications identified were atomoxetine, bupropion, modafinil and desipramine. The 29 trials were stratified based on the three classes of drug studied (i.e., long-acting stimulant vs. short-acting stimulant vs. non-stimulant).

The researchers compared study outcomes using effect sizes, a standard statistical measure commonly used in meta-analyses to determine the magnitude of a particular effect resulting from an intervention, such as a drug used on a population, irrespective of the population size. Effect sizes are generally categorized as small (d = 0.2), medium (d = 0.5) and large (d = 0.8). After adjusting for study design differences, the researchers calculated effect size based on Total ADHD scores.

Stimulant medications showed an effect size significantly larger than non-stimulant medications. Within the stimulant class of medications, mixed amphetamine salts/amphetamine formulations demonstrated larger effect size compared to methylphenidate formulations. Results from this study were also recently published in Medscape General Medicine.

Shire Development Inc. supported the study.