AACAP: Growth Reduction Seen Temporary for Children on ADHD Drug

SAN DIEGO, Calif., Oct. 30 -- Strattera (atomoxetine) given to children with attention deficit hyperactivity disorder does not appear to stunt growth over the long term, according to a lengthy study.

Height, weight and body mass index (BMI) percentiles dropped initially with Strattera treatment but returned to pretreatment levels after three years of continual therapy, said Thomas J. Spencer, M.D., of Massachusetts General Hospital and Harvard Medical School, and colleagues, at the American Academy of Child and Adolescent Psychiatry meeting here.

"In many patients, the disorder persists through adolescence into adulthood and therefore may require chronic treatment," Dr. Spencer reported at a poster session. "Few studies have examined the effect of long-term pharmacological treatments for ADHD on growth, as most long-term trials have lasted only one to two years."

During the first 18 months of treatment, the children's height and weight had increased significantly less than expected on the basis on their initial percentiles for age and gender (P<0.05). Weight decrements persisted past 30 months (P<0.05).

However, after five years of treatment the researchers reported:

• Height had normalized to baseline levels (mean percentile 57.9 versus 55.7 baseline, P=0.517, and z-score 0.27 versus 0.23 baseline, P=0.706),
• Weight returned to expected levels (mean percentile 68.9 versus 67.8 baseline, P=0.695, and z-score 0.77 versus 0.72 baseline, P=0.621), and
• BMI had gone back to pretreatment levels (mean percentile 68.1 versus 70.3, P=0.520, and z-score 0.70 versus 0.73, P=0.816).

The study analyzed growth data for 1,312 patients at baseline with DSM-IV defined ADHD (mean age 11.0, range 6 to 17). They received Strattera at 1.8 mg/kg per day in an ongoing open-label treatment trial sponsored by Eli Lilly. At the five year point, only 61 patients remained (average age 10.2).

The researcher found that growth velocity appeared to have normalized for smaller-than-average and larger-than-average children after five years. The findings were:

• Weights for children in the highest quartile (75th to 100th percentiles) dropped (mean percentile 84.0 versus 92.2 baseline, P=0.007).
• The mean BMI fell for those in the highest quartile (75th to 100th percentiles, 83.0 versus 91.1, P=0.026).
• Children who were shortest at baseline (0 to 25th and 25th to 50th percentiles) grew significantly taller than would have been expected for their pretreatment percentile (gains of 14.1 and 16.3 percentiles, P=0.048 and P=0.025, respectively).

The authors concluded that continual ADHD treatment may have minimal long-term effects.

"Individual patients, however, may show more or less pronounced effects," they wrote. "It is therefore important for clinicians to assess growth periodically during treatment, and for those patients who appear to be growing more slowly than expected, to consider whether treatment with atomoxetine is a factor."

The research was funded by Eli Lilly. Dr. Spencer reported research support and other financial relationships to Eli Lilly.