title: Long-term patient monitoring for clozapine-induced agranulocytosis and neutropenia in Korea: when is it safe to discontinue CPMS?
abstract: OBJECTIVE
  This study documents the incidences of agranulocytosis and neutropenia, and the patterns of incidence of the side effects of long-term clozapine treatment in order to determine an appropriate time to stop the Clozaril Patient Monitoring System (CPMS).
  
  
  METHODS
  Hematological, demographic, and other data from the CPMS for 6782 patients who took clozapine for the past 11 years in the Republic of Korea has been analyzed.
  
  
  RESULTS
  Twenty-nine (53.7%) of fifty-four agranulocytosis cases occurred within the first 18 weeks. The cumulative incidence of agranulocytosis was 1.64% between 6 and 11 years and the crude incidence was 0.8%. Neutropenia occurred in 697 patients, and 365 (52.4%) of these cases occurred within the first 18 weeks. The cumulative incidence of neutropenia was 19.8% between 8 and 11 years, and the crude incidence was 10.3%. There were no cases of agranulocytosis or neutropenia after the 9th year of clozapine treatment.
  
  
  CONCLUSIONS
  The incidence of agranulocytosis in the Republic of Korea was similar to those in the rest of the world. While agranulocytosis began several years after clozapine treatment, long-term monitoring of white blood cells is necessary. We suggest that the CPMS should be stopped or less frequently after the 9th year of treatment.
authors.affiliation: Department of Psychiatry, School of Medicine, Kyungpook National University, Taegu, Republic of Korea. kuhpkbj@knu.ac.kr
authors.forename: Byung-Jo
authors.initials: BJ
authors.lastname: Kang
authors.forename: Man-Je
authors.initials: MJ
authors.lastname: Cho
authors.forename: Jung-Tae
authors.initials: JT
authors.lastname: Oh
authors.forename: Yanghyun
authors.initials: Y
authors.lastname: Lee
authors.forename: Beang-Jin
authors.initials: BJ
authors.lastname: Chae
authors.forename: Jaewook
authors.initials: J
authors.lastname: Ko
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000380:Agranulocytosis / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology; D014150:Antipsychotic Agents / Q000009:adverse effects*; D003024:Clozapine / Q000009:adverse effects*; D016903:Drug Monitoring; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007723:Korea / Q000453:epidemiology; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D009503:Neutropenia / Q000097:blood / Q000139:chemically induced* / Q000453:epidemiology; D013997:Time Factors
chemical_list: D014150:Antipsychotic Agents; D003024:Clozapine