The impact of the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) on prescribing practices: an analysis of data from a large midwestern state.

Background: The Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) was a series of effectiveness trials. The results of these trials began publication in September 2005. Among other findings, these studies were interpreted to suggest that (1) second-generation antipsychotics might have fewer advantages over first-generation antipsychotics than had been generally thought; (2) among the agents assessed, olanzapine had the best efficacy outcome; and (3) after treatment failure with a second-generation antipsychotic, the most efficacious second-line medication is clozapine. To examine the actual impact on practice of these publications, we looked at change in physician prescribing behavior based on these 3 conclusions before and after publication of CATIE.

Method: Rates of antipsychotic medication prescriptions to 51,459 patients with an ICD-9 code of 295 for schizophrenia were extracted from a Missouri Medicaid claims database. χ² Tests were used to compare the rates of prescribing antipsychotic medications before and after each of 3 key CATIE publications (time 1 was September 2005, time 2 was December 2006, and time 3 was April 2006).

Results: At all time points, we demonstrated a decrease in prescriptions by all prescribers for olanzapine (P < .0001). One year after time 1, we found an increase in prescriptions by all prescribers for aripiprazole (P < .0001). No statistically significant increases in clozapine prescribing were observed. Also, a small but statistically significant increase was seen in prescriptions of perphenazine (P < .02 at time 3). However, this increase occurred only for prescriptions written by psychiatrists and not other prescribers.

Conclusions: We found some evidence in our sample that the publication of the results from CATIE had a small but statistically significant effect on prescribing habits of psychiatrists but not other physicians in our sample population. However, larger changes occurred in prescribing behavior that were largely unrelated to the CATIE trial. We propose a hypothesis to explain the direction of observed changes.