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Keywords:

  • seizures;
  • epilepsy;
  • atomoxetine;
  • stimulants;
  • propensity scores;
  • inception cohort;
  • pharmacoepidemiology

ABSTRACT

Purpose

Stimulant medications used for treating attention deficit hyperactivity disorder (ADHD) can be associated with an increased risk of seizures. Atomoxetine is a non-stimulant medication approved for treating ADHD. This retrospective cohort analysis evaluated risk of seizures among pediatric patients naïve to ADHD medication therapy, with exposure to atomoxetine relative to stimulant medications.

Methods

Among members of a large US health plan from 1/1/2003 to 12/31/2006, aged 6–17 years, we identified initiators of atomoxetine or stimulants with no evidence of prior study drug use. We created study cohorts using propensity score matching within 6-month calendar blocks. The outcome was a seizure event in the 6-month follow-up period verified through medical record review. Relative risks (RR) based on current use of each study drug adjusted for baseline covariates were calculated using Poisson regression. We estimated hazard ratios from Cox proportional hazards models for the comparison of atomoxetine to stimulants based on initial cohort assignment.

Results

We matched 13 398 initiators of atomoxetine to 13 322 initiators of stimulants. We identified 97 seizure events. After adjustment, current atomoxetine therapy was associated with a non-statistically significant 28% lower risk of seizure compared to current stimulant therapy (RR 0.72; 95%CI 0.37, 1.38). The adjusted RR of seizure with atomoxetine compared to stimulants based on initial cohort assignment was 0.90 (95%CI 0.54, 1.49).

Conclusions

These results do not support an increase in the risk of seizure with atomoxetine therapy. The risk of seizure was not significantly different between pediatric patients taking atomoxetine compared with those taking stimulants. Copyright © 2012 John Wiley & Sons, Ltd.