Assessment of adherence measures with different stimulants among children and adolescents

Study Objective. To examine adherence measures with different stimulants in children and adolescents. Design. Retrospective analysis. Data Source. Texas Medicaid prescription claims database. Patients. A total of 9549 patients aged 5-18 years with attention-deficit-hyperactivity disorder. Measurements and Main Results. Paid prescription claims for newly started stimulants during the 2001-2002 school year were extracted from a database; 28,344 prescriptions (9549 patients) were available for analysis. Adherence was evaluated based on the drug therapy prescribed (i.e., mixed amphetamine salts, immediate-release methylphenidate, and extended-release methylphenidate-OROS [oral-osmotic formulation]) and the age and sex of the patient. Adherence measures were persistence and medication possession ratio (MPR). Persistence was higher for extended-release methylphenidate-ORCS (0.50 +/- 0.33) than for mixed amphetamine salts (0.42 +/- 0.29) or immediate-release methylphenidate (0.37 +/- 0.26; p < 0.001). The MPR was also higher for extended-release methylphenidate-ORCS (0.76 +/- 0.37) than for mixed amphetamine salts (0.73 +/- 0.37) or immediate-release methylphenidate (0.69 +/- 0.37; p < 0.001). Patients aged 5-9 years had equal or better persistence and MPR than those aged 10-14 and 15-18 years (p < 0.001). No sex-related differences in adherence were observed. Conclusion. Adherence measures in our study were low. Although they were significantly better for extended-release methylphenidate-OROS than the other stimulants, the clinical significance of these differences are unclear. Further research should be conducted regarding pharmaceutical products, administration methods, and clinical interventions that may enhance adherence.