Starting with some definitions. These are not universal, but I’m using the words this way in this post:
- Clinical score: A multi-component clinical assessment tool that involves summing up the numerical values of a set of more than one component. Example: NEWS2
- Clinical scale: A clinical assessment tool consisting of one or more components with a value set, which are not summed into a total score. The component value set items may or may not have numerical values associated with them. Example: New York Heart Association (NYHA) functional classification
This terminology is made even more confusing by the fact that some clinical scores are called “something something scale” (like Braden scale).
Clinical scores are usually represented in archetypes using a set of Ordinal type elements, whose values are summed up in a Count type element. The Ordinal data type makes it easy to associate a computable number with a text string in the value set items, and as such is perfect for this use case.
Clinical scales however, have no use of summing up the values, and as the number of each value set item often needs to be displayed to the clinician as part of the text, there may be value in putting the number in the text string of each value set item. However, if a scale needs to be displayed as a graph on a time scale, that would be an argument for representing it as an ordinal in order to get the computable numerical value.
We have several of published clinical scale archetypes, some of which are using Coded text and some of which are using the Ordinal data type. We’d like to be able to set down a pattern for this kind of archetype in the modelling style guide, but we’re getting mixed response from reviewers and other parts of the openEHR community.
Therefore we’d like to gather all the arguments, clinical, modelling and technical,
- for and against using the Ordinal data type for clinical scales (like in ECOG performance status and Modified Mallampati classification)
- for and against using the Coded text data type for clinical scales (like in Cormack-Lehane classification, NYHA functional classification, Tanner stages and ACVPU scale).