PW01-18 - Utilization and expenditures for lisdexamfetamine dimesylate compared to other attention-deficit/hyperactivity disorder (ADHD) medications in the Texas Medicaid program

Abstract

ObjectivesTo determine if utilization and expenditures differ between a newly-marketed (at time of study) ADHD medication (lisdexamfetamine dimesylate [LDX]) and existing medications.MethodsPrescription and medical claims for Texas Medicaid patients diagnosed with ADHD newly initiated on an ADHD medication (no previous use for 180 days) during August and September 2007 were analyzed. Logistic and linear regressions were used to evaluate differences in adherence, persistence, switching, and expenditures during a 180-day post-initiation period between the LDX group and existing medications (immediate-release methylphenidate [IR-M] and amphetamines [IR-A] and extended-release methylphenidate [ER-M] and amphetamines [ER-A, excluding LDX]) with relevant demographic and preinitiation period comorbidities, utilization, and expenditure variables as covariates. Because prior authorization was required, the non-stimulant atomoxetine was excluded.ResultsThe sample consisted of 1810 subjects with 69% aged 6 to 12 years; 58.0% were initiated on ER-M and 14.4% on LDX. Psychiatrists prescribed 60.5% of LDX prescriptions. A greater proportion of LDX patients had psychiatric-related comorbidities compared to the other medication groups. Logistic regression showed that compared to the LDX group, the IR-M group was more likely to discontinue therapy (OR=1.95, 95%CI=1.05-3.60, P=0.034), and the IR-A group was more likely to switch therapy (OR=2.39, 95%CI=1.22-4.69, P=0.012). ADHD medication expenditures were significantly lower for the LDX group than the ER groups (all P≤0.003). ADHD-related and total medical expenditures did not differ significantly.ConclusionsAlthough used in more complex patients, LDX demonstrated advantages over IR-M on persistence, IR-A on therapy switching, and the ER groups on medication expenditures.