Patient characteristics and the likelihood of initiation on olanzapine or risperidone among patients with schizophrenia

Boston University, Boston, Massachusetts, United States
Schizophrenia Research (Impact Factor: 3.92). 10/2005; 77(2-3):167-77. DOI: 10.1016/j.schres.2005.04.005
Source: PubMed


Although pharmacologic treatments are available for patients with schizophrenia, little is known about how prescription patterns of atypical antipsychotic agents are related to patient characteristics. In this study, we examined the association between patient characteristics and the likelihood of being initiated on olanzapine or risperidone, two of the most frequently prescribed atypical agents for schizophrenia. We selected patients who were diagnosed with schizophrenia or schizoaffective disorder based on > or = 1 inpatient or > or = 2 outpatient ICD-9-CM codes (> or = 7 days apart) between 7/1/98 and 6/30/99 from the Veterans Health Administration (VA). We classified patients into one of three types of initiation: (a) not on olanzapine or risperidone, (b) not on any atypical agents, or (c) not on any antipsychotic agents for 6 months, and then subsequently being prescribed the target drugs. Using logistic regression, we examined whether the odds ratio of being initiated on olanzapine versus risperidone are related to patient sociodemographic and clinical characteristics. Compared to risperidone initiators, olanzapine initiators used more drugs for psychiatric conditions (including antiparkinsonian agents, typical antipsychotics, and mood stabilizers) than risperidone initiators. On the other hand, risperidone initiators had more medical comorbidities and more non-psychiatric hospitalizations. Olanzapine and risperidone appear to be prescribed to patients with different characteristics. Initiation of risperidone was more common among patients who presented with more medical comorbid conditions, whereas initiation of olanzapine was more common among patient who presented with more mental comorbid conditions. Future research needs to determine the reasons for those differences.

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    • "However, considering the inappropriateness of the conventional approach in measuring medication adherence as well as the limitations of the present study, more research is needed to examine the extent to which adjunctive use of other agents, a common practice among patients with schizophrenia,28 dose of treatment, and stage of illness will influence levels of treatment adherence. Future research should also assess the impact of poor treatment adherence on a wide spectrum of patient outcomes.29 A more comprehensive assessment using appropriate analytic methods should provide physicians with a better knowledge about treatment adherence associated with different antipsychotic agents and help them make prescription choices that will ultimately improve the care of schizophrenia. "
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    ABSTRACT: The importance of medication adherence in sustaining control of schizophrenic symptoms has generated a great deal of interest in comparing levels of treatment adherence with different antipsychotic agents. However, the bulk of the research has yielded results that are often inconsistent. In this prospective, observational study, we assessed the measurement properties of 3 commonly used, pharmacy-based measures of treatment adherence with antipsychotic agents in schizophrenia using data from the Veterans Health Administration during 2000 to 2005. Patients were selected if they were on antipsychotics and diagnosed with schizophrenia (N = 18,425). A gap of >/=30 days (with no filled index medication) was used to define discontinuation of treatment as well as medication "episodes," or the number of times a patient returned to the same index agent after discontinuation of treatment within a 1-year period. The study found that the 3 existing measures differed in their approaches in measuring treatment adherence, suggesting that studies using these different measures would generate different levels of treatment adherence across antipsychotic agents. Considering the measurement problems associated with each existing approach, we offered a new, medication episode-specific approach, which would provide a fairer comparison of the levels of treatment adherence across different antipsychotic agents.
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    ABSTRACT: We attempted to determine the decision rules psychiatrists use in the choice of antipsychotic drugs for inpatients with schizophrenia. Interviews were conducted with 50 hospital psychiatrists in Southern Germany. Each physician was interviewed with respect to the reasons for his antipsychotic drug choice in the cases of three patients with a diagnosis of schizophrenia. Interviews were audiotaped and subsequently analyzed using a standardized coding scheme. The clinical decision rules identified are highly complex, with a mean of eight categories cited per patient. Categories named included the patient's past treatment response, side effects, intended route of administration and co-morbidities. Moreover, psychiatrists strongly take the patient's target symptoms and the assumed efficacy of certain compounds into account in their choice of medication. Psychiatrists' explanations for their antipsychotic drug choice seem for the most part reasonable and overlap substantially with drug-choice algorithms of clinical guidelines. However, psychiatrists additionally use indicators that--in their view--might predict treatment response. For these indicators, which are derived from personal experience, it is still unclear whether they are valid and simply have not yet been proven in clinical trials or whether they merely represent unfounded assumptions on the part of the doctors.
    No preview · Article · Jan 2006 · European Journal of Clinical Pharmacology
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    ABSTRACT: Background: Although clinical trials have demonstrated the efficacy of atypical antipsychotic agents in reducing symptoms of schizophrenia, the likelihood of sustaining control of schizophrenic symptoms may depend on treatment persistence. Objective: In this study, we compared treatment persistence between patients who were initiated on risperidone or olanzapine, the two most widely prescribed atypical antipsychotic agents. Method: We identified patients with schizophrenia by ICD-9-CM codes (≥1 inpatient or ≥2 outpatient ICD-9-CM codes ≥7 days apart) between 1 July 1998 and 30 June 1999. We further selected those who were prescribed the target drug during 1 April 1999 through 31 March 2000 provided that they were not on any antipsychotic agents during the prior 6 months. Using event history analysis, we compared the treatment persistence in terms of hazard ratio between olanzapine and risperidone initiators, adjusting for patient's sociodemographic and clinical characteristics. Results: Following the initiation of the target drug, more patients switched from risperidone to olanzapine than vice versa. However, among patients with schizophrenia who had comorbid diabetes, there were more patients who made a switch from olanzapine to risperidone; whereas among those who used anxiolytics, there were more patients who switched from risperidone to olanzapine. Finally, olanzapine initiators had decreased hazards of discontinuation by 14% (unadjusted; P < 0·001) and 12% (adjusted; P = 0·002), respectively, than risperidone initiators. Conclusions: Compared with risperidone, olanzapine seems to be better tolerated by patients as indicated by better treatment persistence. As such, initiation of olanzapine may increase the likelihood of sustaining control of symptoms of schizophrenia. Future research needs to provide a more comprehensive assessment of treatment persistence by considering other antipsychotic agents in the study and developing models to assess treatment persistence and switching as two interdependent competing risks.
    Preview · Article · Jan 2006 · Journal of Clinical Pharmacy and Therapeutics
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