Background: Some recent clinical studies have found that early childhood exposure to anesthesia is associated with increased risks of behavioral deficits and clinical diagnoses of attention deficit hyperactivity disorder (ADHD). While diagnoses in claims data may be subject to inaccuracies, pharmacy claims are highly accurate in reflecting medication use. This study examines the association between exposure to surgery and anesthesia and subsequent ADHD medication use.
Methods: Longitudinal data for children enrolled in Texas and New York Medicaid from 1999 to 2010 were used. We assessed the association between a single exposure to anesthesia before age 5 years for 1 of 4 common pediatric surgical procedures (pyloromyotomy, inguinal hernia repair, circumcisions outside the perinatal period, and tonsillectomy and/or adenoidectomy) and persistent ADHD medication use (event defined as the initial ADHD medication prescription, and persistent use defined as filling 2 or more ≥30-day prescriptions between 6 months following surgery until censoring). Exposed children (n = 42,687) were matched on propensity score (ie, the probability of receiving surgery) estimated in logistic regression including sociodemographic and clinical covariates, to children without anesthesia exposure before age 5 years (n = 213,435). Cox proportional hazards models were used to evaluate the hazard ratio (HR) of ADHD medication use following exposure. Nonpsychotropic medications served as negative controls to determine if exposed children simply had higher overall medication use.
Results: Children with a single exposure to surgery and anesthesia were 37% more likely than unexposed children to persistently use ADHD medication (HR, 1.37; 95% confidence interval [CI], 1.30-1.44). The estimated HRs for common nonpsychotropic medication use following a single anesthetic exposure were 1.06 (95% CI, 1.04-1.07) for amoxicillin, 1.10 (95% CI, 1.08-1.12) for azithromycin, and 1.08 (95% CI, 1.05-1.11) for diphenhydramine. In comparison, the risk of using other psychotropic medication to treat conditions besides ADHD was also significantly higher, with HRs of 1.37 (95% CI, 1.24-1.51) for sedative/anxiolytics, 1.40 (95% CI, 1.25-1.58) for antidepressants, 1.31 (95% CI, 1.20-1.44) for antipsychotics, and 1.24 (95% CI, 1.10-1.40) for mood stabilizers.
Conclusions: Medicaid-enrolled children receiving anesthesia for a single common pediatric surgical procedure under age 5 years were 37% more likely to require subsequent persistent use of ADHD medications than unexposed children. Because the increased use of ADHD medication is disproportionately higher than that of nonpsychotropic medications, unmeasured confounding may not account for all of the increase in ADHD medication use. By evaluating Medicaid data, this study assesses children who may be particularly vulnerable to neurotoxic exposures.