PEDIATRICS Vol. 117 No. 2 February 2006, pp. 587-588 (doi:10.1542/peds.2005-1895)
Absence of Unfavorable Effect of Atomoxetine on Growth in Pediatric Patients Is Still Not Demonstrated
Pietro Panei, MDAnne-Laure Knellwolf, MD
Romano Arcieri, PhD
Stefano Vella, MD
Department of Drug Research and Evaluation,
Italian National Institute of Health,
00161 Rome, Italy
To the Editor.—
We read with interest the article written by Spencer et al.1 The authors concluded that atomoxetine doesn't have an unfavorable effect on growth in pediatric patients. However, some doubts arise about the methods used to support this assertion: height was measured sporadically across several studies of the clinical development program for atomoxetine in which the duration of exposure varied from 3 months to >2 years. The main criterion was based on the change in height from baseline to the end point and compared to predicted normative values. The analysis was performed according to the baseline quartile and the age of the patient at the first atomoxetine dose. The mean patient age at enrollment was 10.6 years; among them, 
70% were 
12 years old. Most of them, therefore, were presumably in pubertal development. Because during this period the height speed increases very fast, it would have been meaningful to take into account in the analysis the pubertal staging by standardizing the population on this parameter or alternatively to perform the analysis without pubertal patients. Because the authors included in the analysis all the patients regardless of their pubertal development, this might have diminished the possible negative effect of atomoxetine on growth.
The authors' assertion that "[i]t is likely that the sample distribution of weight and height was affected at the beginning of the study because of early or late pubertal development and, over the course of the study, moved back toward the population mean as the group became older and differential effects related to the timing of puberty decreased" is questionable, because the pubertal staging and the final stature of the patients were unknown.
The assumption of the authors that atomoxetine has minimal or no effect on growth among pediatric patients seems to us unsupported, because the studies were not designed at the beginning to answer this question. We think also that, to assess the stimulant medication effect on height growth in children,2 longer-term studies are needed, looking at the rate of progression of the bone age and pubertal development.
REFERENCES
- Spencer TJ, Newcorn JH, Kratochvil CJ, Ruff D, Michelson D, Biederman J. Effects of atomoxetine on growth after 2-year treatment among pediatric patients with attention-deficit/hyperactivity disorder. Pediatrics. 2005;116 (1). Available at:www.pediatrics.org/cgi/content/full/116/1/e74
- Poulton A. Growth on stimulant medication; clarifying the confusion: a review.
Arch Dis Child. 2005;90
:801
–806
[Abstract/Free Full Text]
PEDIATRICS (ISSN 1098-4275). ©2006 by the American Academy of Pediatrics
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Related articles in Pediatrics:
- Absence of Unfavorable Effect of Atomoxetine on Growth in Pediatric Patients Is Still Not Demonstrated: In Reply
- Thomas J. Spencer, Joseph Biederman, Jeffrey H. Newcorn, Christopher J. Kratochvil, Dustin Ruff, and David Michelson
Pediatrics 2006 117: 588.[Extract] [Full Text]
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