Predictors of differential response to clozapine and haloperidol. Veterans Affairs Cooperative Study Group on Clozapine in Refractory Schizophrenia.
ABSTRACT We sought to identify baseline predictors of response to clozapine.
Data were from a 15-site randomized clinical trial comparing clozapine and haloperidol in hospitalized patients with refractory schizophrenia (n = 423). Three-month outcomes were analyzed with the full sample (n = 368 due to attrition). Because of crossovers, analyses of 12-month outcomes were conducted with crossovers excluded (n = 291). Clinical predictors included age, race, diagnosis (current substance abuse, paranoid subtype of schizophrenia, or depressive syndrome), severity of symptoms, quality of life, age at onset of schizophrenia, extrapyramidal symptoms, and VA compensation payment. Multiple regression analysis was used to examine the interaction of treatment condition and each of these variables in predicting outcomes for symptoms, quality of life, side effects, and days hospitalized.
Patients with higher quality of life at baseline (p = .04) and higher symptoms (p = .02) had relatively smaller declines in hospital days at 6 months. In the 12-month sample patients with higher levels of symptoms had greater symptom reductions at 12 months (p = .03) and greater improvement in quality of life (p = .004).
Although high levels of symptoms were associated with greater improvement on clozapine, these findings are not robust enough to suggest that any specific, clinically defined subgroup of refractory patients should be preferentially targeted for clozapine treatment.
European Neuropsychopharmacology 09/1999; 9:263-263. DOI:10.1016/S0924-977X(99)80271-5 · 5.40 Impact Factor
European Neuropsychopharmacology 09/1999; 9:262-263. DOI:10.1016/S0924-977X(99)80270-3 · 5.40 Impact Factor
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ABSTRACT: OBJECTIVE: Effectiveness trials have confirmed the superiority of clozapine in schizophrenia treatment, but little is known about whether the drug's superiority holds across racial-ethnic groups. This study examined the effectiveness by race-ethnicity of clozapine relative to other antipsychotics among adult patients in maintenance antipsychotic treatment. METHODS: Black, Latino, and white Florida Medicaid beneficiaries with schizophrenia receiving maintenance treatment with clozapine or other antipsychotics between July 1, 2000, and June 30, 2005, were identified. Cox proportional hazard regression models were used to estimate associations between clozapine and race-ethnicity and their interaction; time to discontinuation for any cause was the primary measure of effectiveness. RESULTS: The 20,122 members of the study cohort accounted for 20,122 antipsychotic treatment episodes; 3.7% were treated with clozapine and 96.3% with other antipsychotics. Blacks accounted for 23% of episodes and Latinos for 36%. Unadjusted analyses suggested that Latinos continued on clozapine longer than whites and that Latinos and blacks discontinued other antipsychotics sooner than whites. Adjusted analyses of 749 propensity score-matched sets of clozapine users and other antipsychotic users indicated that risk of discontinuation was lower for clozapine users (risk ratio [RR]=.45, 95% confidence interval [CI]=.39-.52), an effect that was not moderated by race-ethnicity. Times to discontinuation were longer for clozapine users. Overall risk of antipsychotic discontinuation was higher for blacks (RR=1.56, CI=1.27-1.91) and Latinos (RR=1.23, CI=1.02-1.48). CONCLUSIONS: The study confirmed clozapine's superior effectiveness and did not find evidence that race-ethnicity modified this effect. The findings highlight the need for efforts to increase clozapine use, particularly among minority groups.Psychiatric services (Washington, D.C.) 12/2012; 64(3). DOI:10.1176/appi.ps.201200041 · 1.99 Impact Factor