Semester

Fall

Date of Graduation

2005

Document Type

Dissertation

Degree Type

PhD

College

School of Pharmacy

Department

Pharmaceutical Systems and Policy

Committee Chair

S. Suresh Madhavan.

Abstract

Several atypical antipsychotics have entered the market since the last decade. Evaluating the utilization patterns and overall cost savings generated by these expensive agents is becoming more important as their use continues to expand. Phase 1 of this study describes the patterns of antipsychotic utilization and its impact on total and mental health-related costs for schizophrenia and bipolar disorder patients in a state Medicaid program. Phase 2 of this study compares typical antipsychotics, risperidone, olanzapine, and quetiapine in terms of direct costs and utilization of healthcare services such as hospitalizations, emergency room visits, outpatient visits, psychiatric prescription use and antipsychotic therapy modifications among schizophrenia and bipolar disorder patients. A retrospective, longitudinal study design was employed and a state Medicaid claims data from January 1, 1998 to December 31, 2002 was used. Multivariate analysis was used to statistically control for various confounding factors including patient demographics, prescribing physician type, mental health diagnosis, other comorbidities, pre-index alcohol and substance abuse, pre-index concomitant medication use, and pre-index healthcare utilization. Phase 1 results revealed that a large proportion of schizophrenia and bipolar disorder patients are non-adherent to antipsychotic therapy. Schizophrenia and bipolar disorder patients who are non-adherent to antipsychotic therapy or receive antipsychotic polytherapy incurred significantly higher total and mental healthcare costs. Phase 2 results revealed that there were no significant differences in total and mental healthcare costs among schizophrenia patients initiated on any of the study antipsychotics. Bipolar disorder patients initiated on typical antipsychotics incurred higher total and mental healthcare costs as compared to patients initiated on atypicals. There were no significant differences in total and mental healthcare costs among patients initiated on any of the study atypical antipsychotics. Patients initiated on olanzapine incurred highest pharmacy costs whereas patients initiated on typical antipsychotics incurred lowest pharmacy costs. Schizophrenia and bipolar disorder patients initiated on typical antipsychotics showed significantly lower adherence and higher likelihood of modifying antipsychotic therapy as compared to atypicals.

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