Impact of Atypical Antipsychotic Therapy on Health Outcomes and Costs Among Patients With Major Depressive Disorder

Inclusion Criteria: Patients who meet the following criteria will be included in the study: * aged 18 to 64 years * diagnosis of major depressive disorder during the study timeframe (ICD 9 codes 296.2, 296.3, 311) * evidence of at least 6 consecutive claims for traditional antidepressant therapy with a 30 day supply or at least 2 claims with a 90 day supply (consecutive defined as ≤15 days gap) * must be continually enrolled during the study timeframe and have both medical and pharmacy benefits * evidence of at least 4 consecutive claims for an atypical antipsychotic prescription with a 30 day supply or 2 claims with a 90 day supply (consecutive defined as ≤15 days gap) * evidence of antidepressant therapy for at least 60 consecutive days prior to the initiation of atypical antipsychotic * After at least a 60 day trial of traditional antidepressant medications, patient augments with an atypical antipsychotic medication for at least 4 months. Exclusion Criteria: Patients are excluded if they: * have any claims for a diagnosis of schizophrenia, schizoaffective or bipolar disorder during the study period * have Electroconvulsive therapy (ECT) during the study period * new augmentation with mood stabilizers, L-thyroxine (T4), L-Thyronine (T3), buspirone, stimulant, or others during the post-period (table 1) * are pregnant during the study period * patients with Medicare or Medicaid