Growth on stimulant medication; clarifying the confusion: a review.

AIMS: To get an overview of the studies of growth in height in children with attention deficit hyperactivity disorder (ADHD) treated with stimulant medication, to establish the consistencies and to try to resolve the discrepancies.
METHODS: Twenty nine studies were reviewed following a Medline search: 22 related to children, six to late adolescents or adults, and one to children and adults.
RESULTS: Children: Eleven studies gave results consistent with height attenuation on stimulant medication: eight were longitudinal, one was cross-sectional, and two showed growth rebound on ceasing medication. Studies with negative findings were inadequately powered (n = 3), lacked controls or statistical analysis (n = 3), measured height velocity without reference to treatment duration (n = 2), or used inappropriate growth parameters (n = 1), controls (n = 1), or normative data (n = 1). Late adolescents/adults treated with stimulant medication in childhood: Two studies associated childhood gastrointestinal side effects with attenuated late adolescent or adult height; all six cross-sectional studies had negative findings. The methodologies varied widely but there was some consistency in the degree of attenuation shown in studies with positive findings. The most sensitive methods analysed the changes in z-scores (standard deviation scores) or calculated the height deficits from paired measurements taken before and after an initial period of treatment with stimulant medication. The height deficit amounted to approximately 1 cm/year during the first 1-3 years of treatment.
CONCLUSIONS: Further research is needed into the causal mechanisms, the rate of physical maturation, and the long term implications for final stature.