An examination of factors affecting persistence with initial antipsychotic treatment in patients with schizophrenia

During a schizophrenia treatment episode, persistence with the initial antipsychotic may indicate optimal pharmacotherapy and be a precursor to longer-term effectiveness and other positive outcomes. The objective of this study was to examine the ability of selected variables to predict antipsychotic persistence among patients receiving olanzapine or risperidone as initial treatment.

Data for this analysis, which was not defined in the original study protocol, came from a naturalistic, randomized, open-label trial comparing costs and effectiveness of first-line antipsychotic treatment options in schizophrenia. Predictor variables were as follows: (1) patients' initial antipsychotic (olanzapine [n = 222] or risperidone [n = 218]); (2) current (within 30 days) comorbid diagnosis of substance abuse; and (3) nine self-report items from the Rating of Medication Influence (ROMI) scale, including an item assessing patients' perceptions of the role of their therapeutic alliance in their adherence.

For the primary analysis, a stepwise logistic regression was used in predicting antipsychotic persistence of at least 180 days. Variables found to be significantly predictive were included in a second analysis that assessed persistence at additional thresholds (> 90 days, > 270 days, and completion of the 1-year study).

Four variables predicted longer antipsychotic persistence; olanzapine as initial antipsychotic (p = 0.004), absence of comorbid substance abuse (p = 0.025), and two of the ROMI items representing patients' subjective response to treatment--positive relationship with clinical staff (p = 0.048) and fulfillment of life goals (p = 0.050).

Within a randomized trial design, this study corroborated the influence of several factors on antipsychotic persistence in schizophrenia. Results support the importance of the initial antipsychotic treatment option, presence of a comorbid substance abuse diagnosis, and the role of patients' subjective responses. Additional research is needed to further explore these and other factors as predictors of antipsychotic persistence, and of subsequent treatment outcomes.