An alternative approach to measuring treatment persistence with antipsychotic agents among patients with schizophrenia in the Veterans Health Administration

Xinhua S Ren^1,2, Shirley Qian^1,2, Lewis E Kazis^1,2

¹The Center for the Assessment of Pharmaceutical Practices (CAPP), Boston University School of Public Health, Boston, MA, USA ²Center for Health Quality, Outcomes, and Economic Research, Bedford Veterans Affairs Medical Center, Bedford, MA, USA

Abstract: Prior studies have demonstrated the importance of treatment persistence with antipsychotic agents in sustaining control of schizophrenic symptoms. However, the conventional approach in measuring treatment persistence tended to use only the first prescription episode even though some patients received multiple prescriptions (or multiple treatment episodes) of the same medication within one year following the initiation of the index drug. In this study, we used data from the Veterans Health Administration in the United States to assess the extent to which patients received multiple prescriptions. The study found that about a quarter of the patients had two or more treatment episodes and that levels of treatment persistence tended to vary across treatment episodes. Based on these results, we offered an alternative approach in which we calculated treatment persistence with typical and atypical antipsychotic agents separately for patients with one, two, or three treatment episodes. Considering that patients with different number of treatment episodes might differ in disease profiles, this treatment episode-specific approach offered a fair comparison of the levels of treatment persistence across patients with different number of treatment episodes. Future research needs to extend the analyses beyond two antipsychotic classes to individual antipsychotic agents. A more comprehensive assessment using appropriate analytic methods should help physicians make prescription choices that will ultimately improve the care of patients with schizophrenia.

Keywords: treatment persistence (or discontinuation), treatment episode, antipsychotic agents, schizophrenia