title: Association between second-generation antipsychotic medication half-life and hospitalization in the community treatment of adult schizophrenia.
abstract: OBJECTIVE
  To examine the effect of antipsychotic medication half-life on the risk of psychiatric hospital admission and emergency department (ED) visits among adults with schizophrenia.
  
  
  METHODS
  Retrospective claims-based cohort study of adult Medicaid patients with schizophrenia who were prescribed second-generation antipsychotic monotherapy following hospital discharge between 1/1/04 and 12/31/06. Cox proportional hazards models were applied to compare adjusted hazards of mental disorder admission among patients treated with oral antipsychotics that have either a long [risperidone (t(1/2) = 20 h), olanzapine (t(1/2) = 30 h), aripiprazole (t(1/2) = 75 h)] (n = 1479) or short [quetiapine (t(1/2) = 6 h), ziprasidone (t(1/2) = 7 h)] (n = 837) half-life. Day-level models controlled for baseline background characteristics and antipsychotic adherence over time as measured by gaps in the prescription record. Similar analyses examined either hospitalization or ED visits as separate endpoints.
  
  
  RESULTS
  A significantly lower rate of hospitalization/ED visits was evident for long (0.74/patient-year) vs short (1.06/patient-year) half-life antipsychotics (p < 0.001). The unadjusted rate of hospitalization alone was significantly lower for long (0.38/patient-year) vs short (0.52/patient-year) half-life antipsychotics (p = 0.005). Compared with short half-life antipsychotic drugs, the adjusted hazard ratio associated with long half-life medications was 0.77 (95% CI = 0.67-0.88) for combined hospitalization/ED visits and 0.80 (95% CI = 0.67-0.96) for hospitalization. The corresponding number needed to treat with long, rather than short, half-life medications to avoid one hospitalization was 16 patients for 1 year and to avoid one hospitalization or ED visit was 11 patients for 1 year.
  
  
  CONCLUSIONS
  This study demonstrated an association between antipsychotic medication half-life and hospitalization, not a causal link. Patients using long half-life medications had fewer comorbid mental health conditions and took fewer psychiatric medications at baseline. Other unmeasured differences may have existed between groups and may partially account for the findings.
  
  
  CONCLUSIONS
  In schizophrenia management, longer-acting second-generation antipsychotics were associated with a lower risk of hospital admission/ED visits for mental disorders.
authors: Bristol-Myers Squibb Company, Plaisboro, NJ, USA.
authors: Michael S
authors: MS
authors: Broder
authors: John A
authors: JA
authors: Bates
authors: Yonghua
authors: Y
authors: Jing
authors: Tony
authors: T
authors: Hebden
authors: Robert A
authors: RA
authors: Forbes
authors: Eunice
authors: E
authors: Chang
mesh_terms: D000328:Adult; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000009:adverse effects*; D015331:Cohort Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006207:Half-Life; D006760:Hospitalization / Q000639:trends*; D006801:Humans; D007345:Insurance Claim Review; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment; D018967:Risperidone / Q000008:administration & dosage / Q000009:adverse effects*; D012559:Schizophrenia / Q000188:drug therapy*; D014481:United States
chemical_list: D014150:Antipsychotic Agents; D018967:Risperidone