The Impact of Three-Tier Formularies on Treatment of Attention-Deficit/Hyperactivity Disorder in Children

BACKGROUND: Expenditures for medications used to treat attention-deficit/hyperactivity disorder (ADHD) in children have increased rapidly. Many employers and health plans have adopted 3-tier formularies in an attempt to control costs for these and other drugs. OBJECTIVE: To assess the effect of copayment increases associated with 3-tier formulary adoption on use and spending patterns for ADHD medications for children. DESIGN AND SETTING: Observational study using quasi-experimental design to compare effects on ADHD medication use and spending for children enrolled as dependents in an employer-sponsored plan that made major changes to its pharmacy benefit design and a comparison group of children covered by the same insurer. The plan simultaneously moved from a 1-tier (same copayment required for all drugs) to a 3-tier formulary and implemented an across-the-board copayment increase. The plan later moved 3 drugs from tier 3 to tier 2. PARTICIPANTS: An intervention group of 20 326 and a comparison group of 15 776 children aged 18 years and younger. MAIN OUTCOME MEASURES: Monthly probability of using an ADHD medication; plan, enrollee, and total ADHD medication spending; and medication continuation. RESULTS: A 3-tier formulary implementation resulted in a 17% decrease in the monthly probability of using medication (P