title: The validity and reliability of the global index of safety (GIS).
abstract: OBJECTIVE
  The global index of safety (GIS) is an adverse event (AE) based instrument designed to evaluate the safety profile of drugs. This paper presents the evaluation of the inter-rater reliability and validity of a 94-item GIS for antipsychotics through Rasch analysis.
  
  
  METHODS
  A total of 194 psychiatrists participating in an outpatient pharmacoepidemiologic study of olanzapine in schizophrenia rated the severity that each AE would have on a 5-point scale. Reliability was determined through a paired comparison design involving the new independent ratings of 101 different psychiatrists participating in another study of olanzapine in acute inpatient units. Spearman's, Pearson's and Intra-class correlation (ICC) coefficients were used to estimate the inter-rater reliability of the AE weights. Validity was analyzed through the Rasch rating scale model.
  
  
  RESULTS
  Reliability coefficient estimates were excellent (Spearman = 0.99, Pearson = 0.99, ICC = 0.98), supporting the inter-rater reliability of the item weights. Through goodness-of-fit statistics and the investigation of the hierarchy of item calibrations, Rasch analysis confirmed the validity of the instrument.
  
  
  CONCLUSIONS
  The data presented here on inter-rater reliability estimates of adverse events related to antipsychotic drugs indicate that GIS is a promising alternative for the evaluation of the safety profile of drugs.
authors.affiliation: Health Outcomes Research Unit, Eli Lilly & Co., Alcobendas (Madrid), Spain. prieto_luis@lilly.com
authors.forename: L
authors.initials: L
authors.lastname: Prieto
authors.forename: J A
authors.initials: JA
authors.lastname: Sacristán
authors.forename: J C
authors.initials: JC
authors.lastname: Gómez
mesh_terms: D016907:Adverse Drug Reaction Reporting Systems / Q000592:standards*; D014150:Antipsychotic Agents / Q000009:adverse effects*; D001569:Benzodiazepines / Q000009:adverse effects*; D006801:Humans; D015588:Observer Variation; D000077152:Olanzapine; D012449:Safety / Q000592:standards*; D012559:Schizophrenia / Q000188:drug therapy
chemical_list: D014150:Antipsychotic Agents; D001569:Benzodiazepines; D000077152:Olanzapine