Predictors of differential response to clozapine and haloperidol. Veterans Affairs Cooperative Study Group on Clozapine in Refractory Schizophrenia.
BACKGROUND
We sought to identify baseline predictors of response to clozapine.


METHODS
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.


RESULTS
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).


CONCLUSIONS
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.
Rosenheck
R
R
VA Connecticut Healthcare System, West Haven, Connecticut 06516-2770, USA.
Lawson
W
W
Crayton
J
J
Cramer
J
J
Xu
W
W
Thomas
J
J
Stolar
M
M
Charney
D
D
D000328:Adult; D000367:Age Factors; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D003024:Clozapine / Q000627:therapeutic use*; D004311:Double-Blind Method; D004351:Drug Resistance; D005260:Female; D006220:Haloperidol / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales; D011788:Quality of Life; D044469:Racial Groups; D012559:Schizophrenia / Q000188:drug therapy* / Q000503:physiopathology / Q000534:rehabilitation; D012565:Schizophrenic Psychology; D012944:Social Support; D016896:Treatment Outcome; D014481:United States; D014493:United States Department of Veterans Affairs
D014150:Antipsychotic Agents; D003024:Clozapine; D006220:Haloperidol