title: Clinical consequences of switching from olanzapine to risperidone and vice versa in outpatients with schizophrenia: 36-month results from the Worldwide Schizophrenia Outpatients Health Outcomes (W-SOHO) study.
abstract: BACKGROUND
  With many atypical antipsychotics now available in the market, it has become a common clinical practice to switch between atypical agents as a means of achieving the best clinical outcomes. This study aimed to examine the impact of switching from olanzapine to risperidone and vice versa on clinical status and tolerability outcomes in outpatients with schizophrenia in a naturalistic setting.
  
  
  METHODS
  W-SOHO was a 3-year observational study that involved over 17,000 outpatients with schizophrenia from 37 countries worldwide. The present post hoc study focused on the subgroup of patients who started taking olanzapine at baseline and subsequently made the first switch to risperidone (n=162) and vice versa (n=136). Clinical status was assessed at the visit when the first switch was made (i.e. before switching) and after switching. Logistic regression models examined the impact of medication switch on tolerability outcomes, and linear regression models assessed the association between medication switch and change in the Clinical Global Impression-Schizophrenia (CGI-SCH) overall score or change in weight. In addition, Kaplan-Meier survival curves and Cox-proportional hazards models were used to analyze the time to medication switch as well as time to relapse (symptom worsening as assessed by the CGI-SCH scale or hospitalization).
  
  
  RESULTS
  48% and 39% of patients switching to olanzapine and risperidone, respectively, remained on the medication without further switches (p=0.019). Patients switching to olanzapine were significantly less likely to experience relapse (hazard ratio: 3.43, 95% CI: 1.43, 8.26), extrapyramidal symptoms (odds ratio [OR]: 4.02, 95% CI: 1.49, 10.89) and amenorrhea/galactorrhea (OR: 8.99, 95% CI: 2.30, 35.13). No significant difference in weight change was, however, found between the two groups. While the CGI-SCH overall score improved in both groups after switching, there was a significantly greater change in those who switched to olanzapine (difference of 0.29 points, p=0.013).
  
  
  CONCLUSIONS
  Our study showed that patients who switched from risperidone to olanzapine were likely to experience a more favorable treatment course than those who switched from olanzapine to risperidone. Given the nature of observational study design and small sample size, additional studies are warranted.
authors.affiliation: Personal Social Services Research Unit, London School of Economics and Political Science, Houghton Street, London, WC2A 2AE, UK. j.hong@lse.ac.uk
authors.forename: Jihyung
authors.initials: J
authors.lastname: Hong
authors.forename: Diego
authors.initials: D
authors.lastname: Novick
authors.forename: Roberto
authors.initials: R
authors.lastname: Brugnoli
authors.forename: Jamie
authors.initials: J
authors.lastname: Karagianis
authors.forename: Martin
authors.initials: M
authors.lastname: Dossenbach
authors.forename: Josep Maria
authors.initials: JM
authors.lastname: Haro
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D014150:Antipsychotic Agents / Q000008:administration & dosage / Q000009:adverse effects; D001569:Benzodiazepines / Q000008:administration & dosage / Q000009:adverse effects; D006801:Humans; D008875:Middle Aged; D000077152:Olanzapine; D010045:Outpatients; D011569:Psychiatric Status Rating Scales; D018967:Risperidone / Q000008:administration & dosage / Q000009:adverse effects; D012559:Schizophrenia / Q000188:drug therapy*; D013997:Time Factors; D055815:Young Adult
chemical_list: D014150:Antipsychotic Agents; D001569:Benzodiazepines; D018967:Risperidone; D000077152:Olanzapine