Clozapine-induced fevers and 1-year clozapine discontinuation rate.
BACKGROUND
Clozapine-induced fever is a known side effect that can occur during clozapine initiation. This study aims to characterize patients who experience clozapine-induced fever, the nature of the fevers, and rates of clozapine continuation at 1 year in patients who develop fever versus those who do not.


METHODS
A retrospective chart review of 93 consecutive clozapine initiations (1991-1999) was conducted. Fever was defined as any 1 temperature at or above 38.0 degrees C (100.4 degrees F). Demographic information, presence or absence of clozapine-induced fevers, and continuation of clozapine treatment at 1 year were extracted from the charts. These variables were analyzed for significance, and subsample analysis was conducted for those with more severe fevers (at or above 38.5 degrees C [101.3 degrees F]).


RESULTS
Of the 93 patients, 20.4% (N = 19) developed clozapine-induced fevers. At 1 year, there was no significant difference in clozapine discontinuation rate between those patients who experienced fever and those who did not. Patients who experienced higher fevers (> or = 38.5 degrees C [101.3 degrees F]) tended to be significantly older than those who did not (p < .027). The mean fever duration was 3.8 days (range, 1-9 days), with a mean temperature of 39.1 degrees C (102.4 degrees F) (range, 38.0-41.0 degrees C [100.4-105.8 degrees F]). At 1 year, the patients who experienced fever showed no increased risk of severe reactions such as agranulocytosis. All patients with fevers continued clozapine treatment with good 1-year continuation rate on treatment with this medication.


CONCLUSIONS
Clozapine-induced fever is not an indication for discontinuing this effective medication. It is a benign, self-limited phenomenon not predictive of drug discontinuation at 1 year. Older age at time of treatment may be a risk factor for developing clozapine-induced fever.
Tham
Joseph C
JC
Department of Neuropsychiatry, University of British Columbia Hospital, Vancouver, Canada. drjoe@canoemail.com
Dickson
Ruth A
RA
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001831:Body Temperature; D003024:Clozapine / Q000008:administration & dosage* / Q000009:adverse effects* / Q000627:therapeutic use; D004334:Drug Administration Schedule; D005260:Female; D005334:Fever / Q000139:chemically induced* / Q000175:diagnosis; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000188:drug therapy; D012189:Retrospective Studies; D012307:Risk Factors; D012559:Schizophrenia / Q000188:drug therapy; D012720:Severity of Illness Index; D016896:Treatment Outcome
D003024:Clozapine