Clozapine-induced agranulocytosis in Japan: Changes in leukocyte/neutrophil counts before and after discontinuation of clozapine

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/mm3 were defined as having agranulocytosis, and those with a leukocyte count <3,000/mm3 or a neutrophil count <1,500/mm3 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