Inter-rater reliability of a classification system for hospital adverse drug event reports.

Hospital pharmacovigilance systems frequently classify adverse drug event (ADE) reports on various axes such as severity and type of outcome in an attempt to better detect changes in the frequency of certain types of ADEs. The aim of this study was to measure the inter-observer reliability of an ADE classification system. Two pharmacists and two internal medicine physicians reviewed 150 pharmacist-generated ADE reports and used a structured form to classify reports on four domains: the presence or absence of process measures leading to ADE; the individual who initiated the process that potentially leads to ADE; the severity of ADE; and whether the ADE was related to dose. There was wide variation in inter-observer reliability of different elements in a classification system for ADEs. Agreement on specific processes associated with ADEs ranged from poor to moderate, which limits the ability to target accurately processes to improve drug utilization.