How are medication errors defined? A systematic literature review of definitions and characteristics

Multiplicity in terminology has been suggested as a possible explanation for the variation in the prevalence of medication errors. So far, few empirical studies have challenged this assertion. The objective of this review was, therefore, to describe the extent and characteristics of medication error definitions in hospitals and to consider the consequences for measuring the prevalence of medication errors. Studies were searched for in PubMed, PsychINFO, Embase and CINAHL employing primary search terms such as 'medication errors' and 'adverse drug events'. Peer-reviewed articles containing these terms as primary end-points were included. Study country, year, aim, design, data-collection methods, sample-size, interventions and main results were extracted. Forty-five of 203 relevant studies provided a generic definition of medication errors including 26 different forms of wordings. The studies conducted in nine countries represented a variety of clinical settings and the approach was mainly descriptive. Of utmost importance is the documented prevalence of medication errors, which ranged from 2 to 75% with no associations found between definitions and prevalence. Inconsistency in defining medication errors has been confirmed. It appears that definitions and methods of detection rather than being reproducible and reliable methods are subject to the individual researcher's preferences. Thus, application of a clear-cut definition, standardized terminology and reliable methods has the potential to greatly improve the quality and consistency of medication error reporting. Efforts to achieve a common accepted definition that defines the scope and content are therefore needed.