Combination therapy patterns and predictors of ADHD in commercially insured and Medicaid populations.

Several stimulant and nonstimulant medications are used alone or in combination to treat attention-deficit/hyperactivity disorder (ADHD). Little is known about the current prevalence and predictors of combination therapy. This analysis describes ADHD medication use focusing on combination versus monotherapy. Health insurance claims from the Truven Health MarketScan® Commercial Database and Multi-State Medicaid Database were analyzed for patients with an ADHD diagnosis (International Classification of Diseases, Ninth Revision codes 314.0x). Patients included were aged ≥ 6 years as of January 2010, continuously enrolled from July 2009 through December 2010, and had a claim for an ADHD medication in 2010. Medication use was measured in treatment months during 2010. Baseline demographic and clinical predictors of combination therapy (> 1 ADHD medication class in the same month) involving atomoxetine, long-acting stimulants, and α2-adrenergic agonists were explored using logistic regression, with generalized estimating equations to account for within-patient correlation between months. Commercially insured patients with ADHD (N = 211 226) were primarily aged 6 to 17 years (58.4%) and male (61.5%). Attention-deficit/hyperactivity disorder with hyperactivity was present in 15.8% of these patients. Combination therapy was used in 10.3% of 1 125 119 treatment months. Short-acting stimulants and α2-adrenergic agonists had the highest combination use (45.3% and 54.0%, respectively). Patients with ADHD insured through Medicaid (N = 125 104) were primarily aged 6 to 17 years (94.4%) and male (69.5%). Hyperactivity was present in 39.7% of these patients. Combination therapy was used in 24.0% of 721 986 treatment months. Short-acting stimulants, α2-adrenergic agonists, and intermediate-acting stimulants had the highest combination use (70.0%, 63.8%, and 51.8%, respectively). In multivariate models for both data sources, female patients were less likely to use combination therapy. Patients with hyperactivity were more likely to use combination therapy. Tics/Tourette's syndrome was associated with combination therapy for atomoxetine and long-acting stimulants. In commercially insured and Medicaid ADHD populations, combination therapy rates differed by medication class, as did the demographic and clinical characteristics statistically significantly associated with combination therapy. This suggests that these medications may be used differently in clinical practice.