Towards an adverse drug reactions dictionary. Should existing terminologies be harmonized?

Due to the worldwide marketing of drugs, centralization of information is mandatory. Several Adverse Drug Reactions (ADR) terminologies have been proposed. The most widely used are WHO‐ART and COSTART. However, because of cultural differences, all terms do not exist or do not have the same meaning in different languages or countries. Equivalence between terms of different terminologies are difficult to establish, since terms are proposed without definitions or precise guidelines for their use. Definitions given by medical dictionaries do not resolve this difficulty, since they are neither always concordant nor adapted to the level of information contained in spontaneous notifications. Therefore, it seems necessary to create a dictionary specific for ADR, listing all drug‐induced abnormalities and giving for each of them a definition adapted to the information usually available in pharmacovigilance. As most drug reactions are indistinguishable from non‐drug‐induced diseases, this dictionary must be created in concertation with experts in drug toxicity in each medical field, coming from different countries. An example of such an attempt is given; it was possible to draw a dictionary for liver and biliary disorders from an international consensus meeting of experts on definitions and criteria assessment of drug‐induced liver reactions. This approach could make unnecessary the harmonization of the various terminologies, since each of them would have to make a bridge towards a worldwide accepted ADR dictionary.