Hi all I have a series of questions about OpenEHR, but I should start with an introduction.
I am a software engineer for a health systems vender. I am currently implementing something that looks a whole lot like archetypes. I'm currently evaluating OpenEHR to see how much of the thinking or specifics I can use, with the intention of long-term harmonisation with OpenEHR. I'm also an editor of the HL7 V3 data types specification. And sadly, my first question relates to data types, specifically, nulls. I promise to keep away from this subject in the future. The content referred to here is from 7.7.3 in Design Principles v2.4 The OpenEHR approach is to include a second element/attribute that is a comment upon the quality of the first, thereby "avoiding the problem of pseudo-values. The result is that attribute values always satisfy the type rules of the system, and the data interpretation marker indicates how attribute values should be read" Further, there is the comment: >Null values should not be mixed in with the value domains of true >data types, a practice which compromises the comprehensibility and >computability of data; they should be represented using a distinct data >interpretation marker associated with each data value. I believe that this has merely shunted the problem around, it hasn't actually solved anything. The first issue for me is the idea that "attribute values always satisfy the type rules of the system". If I don't know the value, then I might not be able to provide information in the record to meet these requirements. For instance, say that the element is a simple integer, and I don't know what the value is. What can I place in the element so that it is a valid integer? I worry that this will lead to fabrication of data. A possible response to this is that you don't represent the element, and it has an implicit value of... null? The second issue I have is that it is claimed that the introduction of a datum interpretation indicator is "safer" for applications. I don't see why it's safer - less chance of bugs - to have the option of overlooking the data quality indicator rather than being forced to deal with it since it's built into the type somehow. You can clearly fail to deal with it either way, but you don't so easily entirely miss the quality assessment The third issue is the presence of such a datum interpretation indicator - will it actually be available when I want it? What will I do when I don't have the information but there is no spot for my system to say so? How will my system even know that a given attribute has a datum interpretation indicator associated with it? This last question raises another question - where are such datum interpretation indicators introduced - in the reference model, or the archetypes? This is part of a bigger question, which I will return to later (and is my major concern) - can archetypes actually work in practice at all? (but don't try to answer this till I have added more to this question later) Grahame - If you have any questions about using this list, please send a message to d.lloyd at openehr.org
