Antipsychotic prescription use and costs for persons with schizophrenia in the 1990s: current trends and five year time series forecasts

Abstract Real advances in schizophrenia pharmacotherapy have been made over this decade with the development of more efficacious treatment options with fewer side-effects. These advances have high per-unit direct costs that may have a profound effect on drug budgets of systems caring for persons with schizophrenia. The objective of this study was to describe the changes in utilization and cost for antipsychotic prescriptions by atypical, clozapine, decanoate products, and traditional neuroleptics in a large naturalistic setting, i.e. the Georgia Medicaid population. Secondly, this study forecasted the categorized antipsychotic prescription utilization through the year 2002. Administrative claims data spanning 1990–1997 for Medicaid eligible persons suffering from schizophrenia in the state of Georgia were supplemented with psychiatric institutional data obtained from the Georgia Department of Human Resources. A total of 16 227 Medicaid-eligible recipients had a code indicative of schizophrenia (ICD-9-CM=295. ∗∗ ) and were at least 16 years of age at the time of their first diagnosis. The mean recipient prescription use and expenditures were tallied for each month of the study and stratified by prescription category (atypical, clozapine, decanoate, and traditional antipsychotic). ARIMA time series models were identified and estimated using these monthly PMPM utilization and expenditures estimates to forecast 5 years beyond the last month of the study. The total use of antipsychotics increased modestly throughout the study period, and the use of atypicals, clozapine, and decanoate products increased substantially, while a decrease was observed for traditional antipsychotics. In 1995 dollars, antipsychotic expenditures increased from a mean of approximately $10 PMPM in 1990 to $95 projected for the year 2002. This transition from traditional oral antipsychotics to atypicals and decanoate products has a profound effect on drug expenditures for systems paying for the care of persons with schizophrenia. Further studies to determine the value of the transitions of therapy described in this study need to be evaluated using a system-wide- or Medicaid perspective.