Clozapine underutilization and discontinuation in African Americans due to leucopenia.
Clozapine use has been notably lower in African American patients than in Caucasians. It has been suggested that lower normal ranges for white blood cell (WBC) counts in African Americans, known as benign ethnic neutropenia, may account partially for the disparity. We examined the rates of leucopenia and agranulocytosis as reasons for discontinuation of clozapine in a sample of 1875 patients with schizophrenia treated in the State of Maryland. Between 1989 and 1999, 5.3% (31/588) of African Americans and 2.4% (31/1287) of Caucasians discontinued clozapine treatment due to leucopenia (chi square = 10.35, df = 1, P = 0.001). No African American patients developed agranulocytosis while 8 Caucasian patients (0.62%) developed this blood dyscrasia. Discontinuations due to leucopenia occurred throughout treatment. Discontinuations due to agranulocytosis occurred primarily in the first 18 weeks (7/8; 87.5% patients with agranulocytosis). It is likely that African Americans had clozapine discontinued unnecessarily due to benign ethnic neutropenia. We concur with recent recommendations to acknowledge differences in WBC values in African Americans and to modify prescribing guidelines or formally acknowledge benign ethnic leucopenia like in other countries in order to facilitate greater use of clozapine in these patients.
Kelly
Deanna L
DL
The Maryland Psychiatric Research Center, Box 21247, Baltimore, MD 21228, USA. dkelly@mprc.umaryland.edu
Kreyenbuhl
Julie
J
Dixon
Lisa
L
Love
Raymond C
RC
Medoff
Deborah
D
Conley
Robert R
RR
D001741:Black or African American / Q000235:genetics / Q000706:statistics & numerical data*; D000380:Agranulocytosis / Q000139:chemically induced / Q000453:epidemiology; D014150:Antipsychotic Agents / Q000009:adverse effects / Q000627:therapeutic use; D003024:Clozapine / Q000009:adverse effects* / Q000627:therapeutic use; D004363:Drug Utilization / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007958:Leukocyte Count / Q000706:statistics & numerical data; D007962:Leukocytes / Q000187:drug effects; D007970:Leukopenia / Q000139:chemically induced* / Q000453:epidemiology / Q000235:genetics; D008297:Male; D008396:Maryland / Q000453:epidemiology; D008875:Middle Aged; D010597:Pharmacogenetics; D012559:Schizophrenia / Q000188:drug therapy*; D016896:Treatment Outcome; D044465:White People / Q000706:statistics & numerical data
D014150:Antipsychotic Agents; D003024:Clozapine