Objective: Identify moderators of treatment outcome from antipsychotic pharmacotherapy in the Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trial. Specifically, we used logistic regression and receiver operating characteristic (ROC) analysis to explore the association between baseline characteristics and treatment outcomes in the CATIE trial.
Method: This is a secondary analysis of the CATIE trial in which 1,460 adults with a DSM-IV diagnosis of schizophrenia were randomly assigned to olanzapine, perphenazine, quetiapine, risperidone, or ziprasidone treatment for up to 18 months or until discontinuation between January 2001 and December 2004. Logistic regression was used to examine baseline characteristics associated with remission, response, and treatment continuation at 3 and 6 months of treatment. ROC analyses identified subgroups associated with similar likelihood of treatment outcome. Remission was defined by scores of selected items on psychoticism, disorganization, and negative symptoms. Response was defined as a 50% or greater improvement on the Positive and Negative Syndrome Scale.
Results: The most consistent predictors of poor outcome on all variables were low scores on neurocognitive tests (in particular verbal memory) (OR = 1.13-1.49, P< .05); previous reported side effects (OR = 0.49-0.69, P < .05); negative attitude to medication (OR = 1.03-1.10, P < .05); comorbid depression (OR = 0.47-0.51, P < .05); psychosocial factors such as unemployment (OR = 0.74-0.75, P <.05), homelessness (OR = 0.54, P <.05), and living alone (OR = 1.58-1.94, P < .01); and random assignment to a medication other than olanzapine (OR = 1.54-2.04, P < .01). ROC analysis demonstrated prognostic subgroups with large differences in response likelihood.
Conclusion: Baseline characteristics in schizophrenia are informative regarding clinically important treatment outcomes with respect to antipsychotic pharmacotherapy. Further research should examine whether interventions that target improvement of patients' deficits in neuropsychological function and attitude toward medication as well as decreasing patients' social isolation can improve treatment outcomes with antipsychotic treatment in schizophrenia.
Trial registration: ClinicalTrials.gov identifier: NCT00014001.
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