The validity and reliability of the global index of safety (GIS).
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.
Prieto
L
L
Health Outcomes Research Unit, Eli Lilly & Co., Alcobendas (Madrid), Spain. prieto_luis@lilly.com
Sacristán
J A
JA
Gómez
J C
JC
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
D014150:Antipsychotic Agents; D001569:Benzodiazepines; D000077152:Olanzapine