title: Antipsychotic reexposure and recurrent pneumonia in schizophrenia: a nested case-control study.
abstract: Few studies have used systematic datasets to assess the safety of antipsychotic rechallenge after an adverse event. This nested case-control study estimated the risk for recurrent pneumonia after reexposure to antipsychotic treatment.
  
  
  
  In a nationwide schizophrenia (ICD-9-CM code 295) cohort (derived from the National Health Insurance Research Database in Taiwan) who were hospitalized for pneumonia (ICD-9-CM codes 480-486, 507) between 2000 and 2008 (N = 2,201), we identified 494 subjects that developed recurrent pneumonia after a baseline pneumonia episode. Based on risk-set sampling in a 1:3 ratio, 1,438 matched controls were selected from the cohort. Exposures to antipsychotics were categorized by type, duration, and defined daily dose. Using propensity score-adjusted analysis, we assessed individual antipsychotics for the risk of recurrent pneumonia; we furthermore assessed the effect of reexposure to these antipsychotics on the risk of recurrent pneumonia.
  
  
  
  Of the antipsychotics studied, current use of clozapine was the only one associated with a clear dose-dependent increase in the risk for recurrent pneumonia (adjusted risk ratio = 1.40, P = .024). Intriguingly, patients reexposed to clozapine had a higher risk for recurrent pneumonia (adjusted risk ratio = 1.99, P = .023) than those receiving clozapine only prior to the baseline pneumonia, and this risk was associated with gender. Women reexposed to clozapine were more susceptible to recurrent pneumonia (adjusted risk ratio = 4.93, P = .050).
  
  
  
  In patients experiencing pneumonia while undergoing clozapine treatment, physicians should carefully consider the increased risk of pneumonia recurrence when clozapine is reintroduced. Future studies should try to quantify the risk of other medical conditions associated with clozapine reexposure.
authors.affiliation: Taipei City Psychiatric Center, Taipei City Hospital, Taipei, Taiwan|Department of Public Health, School of Medicine, National Yang Ming University, Taipei, Taiwan
authors.forename: Galen Chin-Lun
authors.initials: GC
authors.lastname: Hung
authors.affiliation: Taipei City Psychiatric Center, Taipei City Hospital, Taipei, Taiwan|Department of Psychiatry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan|Psychiatric Research Center, Taipei Medical University Hospital, Taipei, Taiwan
authors.forename: Hsing-Cheng
authors.initials: HC
authors.lastname: Liu
authors.affiliation: Taipei City Psychiatric Center, Taipei City Hospital, Taipei, Taiwan|Graduate Institute of Clinical Pharmacy, College of Pharmacy, Kaohsiung Medical University, Kaohsiung, Taiwan
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Yang
authors.affiliation: Taipei City Psychiatric Center, Taipei City Hospital, Taipei, Taiwan|Department of Psychology, National Chengchi University, Taipei, Taiwan
authors.forename: Chun-Hung
authors.initials: CH
authors.lastname: Pan
authors.affiliation: Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan
authors.forename: Ya-Tang
authors.initials: YT
authors.lastname: Liao
authors.affiliation: Taipei City Psychiatric Center, Taipei City Hospital, Taipei, Taiwan|Department of Psychiatry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan|Psychiatric Research Center, Taipei Medical University Hospital, Taipei, Taiwan|Department of Psychiatry, Mackay Memorial Hospital, Taipei, Taiwan|Department of Psychiatry, Mackay Medical College, Taipei, Taiwan
authors.forename: Chiao-Chicy
authors.initials: CC
authors.lastname: Chen
authors.affiliation: Taipei City Psychiatric Center, Taipei City Hospital, Taipei, Taiwan|Department of Psychiatry, School of Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan|Psychiatric Research Center, Taipei Medical University Hospital, Taipei, Taiwan|Department of Education and Research, Taipei City Hospital, Taipei, Taiwan
authors.forename: Chian-Jue
authors.initials: CJ
authors.lastname: Kuo
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000008:administration & dosage* / Q000009:adverse effects* / Q000627:therapeutic use; D016022:Case-Control Studies; D003024:Clozapine / Q000009:adverse effects / Q000627:therapeutic use; D016208:Databases, Factual; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000139:chemically induced* / Q000150:complications*; D012008:Recurrence; D012307:Risk Factors; D012559:Schizophrenia / Q000150:complications* / Q000188:drug therapy*; D012727:Sex Characteristics; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D003024:Clozapine