Clozapine‐induced agranulocytosis in Japan: Changes in leukocyte/neutrophil counts before and after discontinuation of clozapine
Kentaro Matsui, Mikiko Ishibashi, M Kawano, Hidehiro Oshibuchi, Jun Ishigooka, Katsuji Nishimura, Ken Inada
Abstract
Abstract Objective To determine the prevalence, background factors, and progression of and recovery from clozapine‐induced agranulocytosis in Japan. Methods Data on treatment‐resistant schizophrenia patients registered with the Clozaril Patient Monitoring Service (CPMS) between July 29, 2009 and January 20, 2016 were extracted. Patients with a neutrophil count <500/mm 3 were defined as having agranulocytosis, and those with a leukocyte count <3,000/mm 3 or a neutrophil count <1,500/mm 3 but not meeting the criteria for agranulocytosis were defined as having leukopenia/neutropenia. Results Of 3,746 patients, agranulocytosis and leukopenia/neutropenia were observed in 38 (1.0%) and 182 (4.9%) patients, respectively. Age was significantly higher in the agranulocytosis group ( p < .001). Decreased leukocyte counts 1 week prior to discontinuation were observed only in the agranulocytosis group. The median number of days to recovery from agranulocytosis and leukopenia/neutropenia was 10 and 4, respectively, with more variation in the latter. Conclusions Although some patients with leukopenia/neutropenia might carry less pathologic significance, the results of this study reconfirmed the importance of regular blood monitoring for preventing agranulocytosis.