To determine if utilization and expenditures differ between ADHD medication classes.

Prescription and medical claims for Texas Medicaid patients with an ADHD diagnosis newly initiated on an ADHD medication (no previous use for 180 days) between January 2006 and September 2007 were analyzed. Logistic and linear regression analyses were used to evaluate differences in adherence, persistence, switching, and expenditures during a 180-day post-initiation observation period across ADHD treatment classes [immediate-release methylphenidate (IR-M) and amphetamines (IR-A) and extended-release methylphenidate (ER-M) and amphetamines (ER-A)] with relevant demographic and pre-initiation period comorbidities, utilization, and expenditure variables as covariates. Because prior authorization was required, the non-stimulant medication atomoxetine was excluded.

The sample consisted of 15,055 subjects with 71% aged 6 to 12 years; 64.7% were initiated on ER-M and 25.4% on ER-A. Compared to the ER-A group, the IR-M (OR=0.56, 95%CI=0.45-0.69) and IRA (OR=0.60, 95%CI=0.46-0.78) groups were less likely to be adherent, more likely to discontinue therapy (OR=2.03, 95%CI=1.67-2.47; and OR=1.77, 95%CI=1.38-2.27; respectively) and more likely to switch medications (OR=2.44, 95%CI=2.05-2.90; and OR=2.85, 95%CI=2.28-3.56; respectively) (all p< 0.001). The ER-A group had significantly higher ADHD medication expenditures compared to other groups (all p≤0.001), but no significant differences in medical expenditures.

Utilization patterns differed across the ADHD medication classes. Most subjects were initiated on ER medications which demonstrated advantages in adherence, persistence, and less switching while the ER-A group, which included more complex patients as indicated by comorbidities, had higher ADHD medication expenditures but no difference in overall medical expenditures.