Date of Award

2019

Degree Type

Thesis

Degree Name

Master of Science in Pharmaceutical Sciences

Department

Pharmaceutical Sciences

First Advisor

Ami Vyas

Abstract

Background: Antipsychotic medications are the first-line treatment for schizophrenia. Medication non-adherence is often a problem among patients with schizophrenia, leading to relapse, rehospitalization, and high cost-burden. First-generation antipsychotics were first developed to treat schizophrenia; however, the higher risk of extra-pyramidal side effects have made them unfavorable in comparison to second-generation antipsychotics (SGA). Nevertheless, antipsychotic adherence is often suboptimal, which can lead to relapse and rehospitalization. Long-acting injectable (LAI) antipsychotics were developed to help improve adherence, thereby reducing rates of relapse. However, this drug class is associated with high treatment cost while the more common oral antipsychotics are inexpensive in comparison.

Methods: Data from Optum’s de-identified Clinformatics® Data Mart Database from years 2010-2015, was utilized to conduct a retrospective cohort study and cost-effectiveness analysis comparing the outcomes and cost of LAI second-generation antipsychotics (SGAs) with oral SGAs for the treatment of schizophrenia. Patients with a history of at least two inpatient hospitalizations for schizophrenia two years prior to a recent relapse hospitalization (index date) during 2012-2014 were identified. Patients were required to have a claim for a LAI SGA or oral SGA within 40 days of discharge from the index hospitalization. Patients were entered into a 12-month follow-up period during which medication cost, adherence, and medication switch or rehospitalization due to relapse were measured. A patient level descriptive analysis was conducted followed by developing a decision model for which an incremental cost-effectiveness ratio (ICER) was estimated comparing incremental cost of treatments and incremental effectiveness.

Results: 158 patients met the study’s inclusion-exclusion criteria. Of 158 patients, 135 (85.4%) had a claim for an oral SGA within 40 days of index discharge and 23 (14.6%) had a claim for a LAI SGA. The mean age of the population was 48-years (standard deviation, SD +12.0) with similar distribution observed in gender (49.4% female). Patients experienced about 4 hospitalizations (SD +2.7) on average, prior to their index date and also had a mean index length of stay of about 10 days (SD +8.8). Compared to patients receiving oral SGAs, patients receiving LAIs experienced numerically higher adherence rates, numerically higher proportion of stable patients, and higher mean cost of medication ($1,339.20 vs. $282.90, p<.0001). A sensitivity analysis determined that change in the proportion of adherent patients prescribed LAIs had a large impact on the ICER value.

Conclusion: Although statistically not significant, the LAI cohort was associated with numerically lower rates of switch or rehospitalization and a higher proportion of adherent patients compared to oral SGAs. While LAIs are associated with a much higher average monthly cost than their oral comparators, the decision analysis indicated that the additional expenditure was associated with improvement in the measured outcome. Further research is warranted examining populations with higher prevalence of schizophrenia to provide larger sample sizes and to measure cost-benefit, which may illustrate cost-avoidance through the cost of rehospitalization due to relapse.

Available for download on Monday, December 13, 2021

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