An alternative terminology for pain assessment

Background: the International Association for the Study of Pain (IASP) publishes since 1986 a relatively frequently updated list of pain terms with corresponding definitions and clarificatory notes currently known as the ‘IASP Taxonomy’. The last update, i.e. the May 2012 version of this taxonomy, was subjected to an analysis with the goal to assess whether the definitions of the IASP terms that are used to describe findings of somatosensory testing and pain assessment satisfy the conditions for these terms to become part of a realism-based ontology. Results: the taxonomy was found to be built on definitions that are not in every case based on necessary and sufficient conditions, nor satisfy the single inheritance principle for realism-based ontologies. Furthermore, although the documentation about introduced changes provided by the IASP makes it clear that the terminology authors tried to solve ambiguities and unclarities present in previous versions, they did not succeed completely and introduced even some inconsistencies. The analysis demonstrates that the main cause for this is not the choice of differentiating characteristics, but rather insufficient attention to the wide variability in stimulus/response combinations that these characteristics reveal. Conclusions: the IASP taxonomy is not fit to form the basis for a realism-based ontology. A new representation framework for describing pain assessment findings more accurately using the same set of differentiae is proposed and its correspondence with the traditional terminology explained. Keywords—pain terminology, ontological realism