Objective:Describe treatment patterns, resource use, and predictors of methylphenidate (MPH) switch among children (6–12 years), adolescents (13–17 years), and adults (≥18 years) with attention-deficit/hyperactivity disorder (ADHD).Methods:This retrospective U.S. managed care database study used medical, pharmacy, and enrollment data to examine treatment patterns among patients with ≥1 ADHD diagnosis code (ICD-9 314.00-314.9), MPH pharmacy claims during 01/01/2004–09/30/2006, and no ADHD pharmacy claims in prior 6 months. Patients were followed for 1 year for dosage change, switch (change to non-MPH treatment), augmentation, persistence (number days on index medication) and adherence (days supplied/days persistent). End points were assessed by age group and MPH formulation. Cox proportional hazards modeling was conducted to determine predictors of MPH switch.Results:Among 23,860 MPH users, 51.4% had a dosing change, 14% switched to a non-MPH agent, and 4% augmented MPH therapy. Among those prescribed long-acting (LA) MPH (N = 14,681), switching rates were 14% for children, 13% for adolescents, and 16% for adults. Augmentation rates for LA MPH were <5%. Overall, 53% of patients were adherent with mean persistence of 219 days. For the subgroup of patients prescribed LA MPH (n = 14,681), adherence ranged from 49% (adolescents) to 59% (children); persistence varied between 183 days (adults) to 256 days (children). During the 1-year follow-up, office/clinic visits were the major driver of health care resource use in MPH patients (mean 9.7 visits/patient). Patients with psychiatric comorbidity utilized significantly greater services. Predictors of MPH switch included psychiatric comorbidity (hazards ratio [HR] 1.37; 95% confidence interval [CI] = 1.26–1.48; p < 0.0001) and specialty prescribers (HR 1.19, 95% CI = 1.04–1.35; p = 0.011). Potential limitations of this study include use of claims data for definition of drug usage; inclusion of medications approved for use in ADHD; assessment of switching that may not have captured short-term augmentation; absence of economic, clinical and other variables from the claims dataset that may have influenced treatment selection, and outcomes. The 6-month baseline period to determine newly treated patients may not guarantee exclusion of all previously treated patients who restart therapy after an extended period.Conclusions:Children exhibited the highest persistence of MPH users. ADHD patients on MPH therapy with a psychiatric comorbidity may require additional follow-up to help improve adherence and reduce health care resource use.