Language Barriers to Defining Concepts in Medicine

Defining a concept is the process of describing its measurable properties and specifying the units of analysis to which the concept applies. Based on the classical concept theory, all concepts have a definitional structure formed by a list of features that must comprise 2 essential attributes, that is, necessity and sufficiency. The former entails that all denoted members share each of the features described, whereas the latter that each feature contains all parts required for a clear and unambiguous definition. Should one of these attributes is not fully satisfied, a definition can be challenged as inadequate, inappropriate, or problematic. Palliative sedation, a medical concept for which numerous attempts at a definition have been recorded over time, can be used as a case in point. The heterogeneity in the definitions proposed for palliative sedation indicates that defining sedation is an area fraught with complexity, with palliative care experts being unable to decide on a standard, widely accepted, definition. Although the lack of a universally agreed term to describe the concept has been frequently argued to contribute to such inability, the actual cause of it is yet to be determined. A quick scan of original definitions of palliative sedation identified between 1945 and 2012 revealed that the attribute of sufficiency, in the definition statements examined, seems to be violated. A systematic analysis of infinitive phrases (to þ verb þ descriptor(s) þ object) employed to describe end-of-life suffering, an essential feature in a palliative sedation definition, showed considerable variation in the way this feature is communicated in written discourse (Figure 1). This variation was found to exceed the choice of verbs, of diverse lexical semantics, used to introduce end-of-life suffering or the objects used to convey the meaning of the feature itself. It was in the choice of descriptive adjectives (henceforth called descriptors) used to ascribe qualities to end-of-life suffering where the major source of inconsistency was observed. Classified into 3 broad categories, mainly associated with nature (describing end-of-life suffering for which all possible treatments have failed, eg, refractory), intensity (describing end-of-life suffering existing or occurring in a high degree/great strength, eg, intolerable), and classification (describing end-of-life suffering of diverse facets, eg, physical), descriptors were frequently observed to violate sufficiency. Classification descriptors were, in most cases, absent or not specified; many intensity descriptors occurred independently, without the presence of a nature descriptor that should actually complement, and interchangeably, being consistently replaced by synonyms; finally, some descriptors falling under the same category were concurrently used, being semantically confused. This violation of sufficiency in describing end-of-life suffering, generating ambiguity relating to the parts this feature should essentially contain, could account for the inability of palliative care experts to decide on a universally agreed definition for palliative sedation. The lack of standard descriptors for end-of-life suffering needs to be highlighted as the main cause of such inability. The variation observed in the current analysis resonates with the results from an expert elicitation study, reporting inconsistencies in the way palliative care experts worldwide perceive and describe end-of-life suffering, reaffirming the need for standard descriptors for end-of-life suffering. Given the focused approach adopted by the current analysis focusing on definition statements alone, however, it would be interesting to explore the way that end-of-life suffering is communicated in a wider written academic discourse context. This interdisciplinary study (currently in progress), bringing together linguistics, palliative medicine, and end-of-life care, could provide better insights into how this feature is linguistically described in the literature of palliative sedation at the end of life, allowing for a more systematic mapping of the variation observed. Evidence will be used as the basis to inform the development of a framework of standard descriptors (forthcoming) required not only to adequately communicate end-of-life suffering in the scientific output of palliative sedation but also to sufficiently address this feature as part of a palliative sedation definition that could potentially gain wider acceptance.