Hi Leo, See http://www.openehr.org/wiki/display/spec/Null+Flavours+and+Boolean+data+in+openEHR
for a decent discussion. My personal take is that expanding the openEHR list to cover 'asked but unknown' might be reasonable, but as Grahame Grieve suggests in one of his comments, the difficulty is that this may often be clinically insufficient or imprecise, depending on context. i.e sometimes clinicians need/want to record even more detail about the reason for the value being null. Grahame has suggested that a text attribute be useful to add to both HL7 and openEHR nulls but I think a more flexible approach is to use a 'Citation' or annotation archetype linked to the Null element via a LINK attribute. This gives systems developers complete flexibility as to the use / degree of structure of the additional data. The current approach that we tend to take with Yes/No constructs and text terms is to model the terms explicitly, according to the clinical requirement. e.g for a finding related to presence of cancer at a surgical resection margin, we have modelled this as Evidence of tumour at margin: Tumour present Tumour absent Indeterminate which matches the Snomed approach. Regards, Ian Dr Ian McNicoll office / fax +44(0)141 560 4657 mobile +44 (0)775 209 7859 skype ianmcnicoll ian.mcnicoll at oceaninformatics.com ian at mcmi.co.uk Clinical Analyst Ocean Informatics openEHR Archetype Editorial Group Member BCS Primary Health Care SG Group www.phcsg.org / BCS Health Scotland On 29 June 2010 14:04, Leonardo Moretti <lmoretti at noemalife.com> wrote: > > Ok, Ian, > using a null value, a null flafour is needed.. For your example cases: > a) The doctor simply did not add any comment. > b) The doctor purposefully 'added an empty string' by clicking through the > data entry widget, perhaps to signify 'no comment'. > c) The doctor couldn't add a comment for some other technical / > environmental reason. > > and looking at codes in section 2.3.7 of > http://www.openehr.org/releases/1.0.2/architecture/terminology.pdf, I > would > use: > for a) and b): HL7_NullFlavor::10614 (AskedButUnknown), but it doens't > have > an analogous values on opeEHR code system > c) HL7_NullFlavor::10614 (temporarily unavailable), but also in this case > it > doens't have an analogous values on opeEHR code system > > > Maybe my perplexity is due to an incomplete value set for Null Flavours > vocabulary found in openEHR specs.. > > Should this vocabulary be extended!? > > Regards > leo > > > > Ian McNicoll-3 wrote: > > > > Hi Leo, > > > > In pure semantic terms I appreciate the difference but this is > practically > > of no value. > > > > What does this empty string mean? > > > > Is it? > > > > a) The doctor simply did not add any comment. > > b) The doctor purposefully 'added an empty string' by clicking through > the > > data entry widget, perhaps to signify 'no comment'. > > c) The doctor couldn't add a comment for some other technical / > > environmental reason. > > > > These are very subtle differences to most clinical staff and I would not > > want to base any safe querying on assumptions that clinicians would > record > > these differences reliably. > > > > If there is a need to positively identify 'no comment', I would model > that > > explicitly but this is rare in clinical practice, and usually is recorded > > for medico-legal reasons rather than future querying e.g. 'No known > > allergies' is a legitimate clinical comment but cannot ever be safely > > queried upon, since the next clinical statement in the record might well > > be > > 'Diagnosis = Penicillin Allergy'. > > > > The most significant principle is that we do not normally record 'empty > > data' at all in openEHR. The data simply does not exist in the clinical > > record. If some sort of comment is mandatory then using the null is the > > means to allow an empty comment. > > > > I have copied ot the clinical list, as it would be interesting to get > some > > other feedback. > > Ian > > > > Dr Ian McNicoll > > office / fax +44(0)141 560 4657 > > mobile +44 (0)775 209 7859 > > skype ianmcnicoll > > ian.mcnicoll at oceaninformatics.com > > ian at mcmi.co.uk > > > > Clinical Analyst Ocean Informatics openEHR Archetype Editorial Group > > Member BCS Primary Health Care SG Group www.phcsg.org / BCS Health > > Scotland > > > > > > > > On 29 June 2010 12:26, Leonardo Moretti <lmoretti at noemalife.com> wrote: > > > >> > >> Hi Ian, > >> in my opinion an empty string has a semantic difference with a null > >> value. > >> Empty string is however a valid value. For example, I could have > >> different > >> cases for "Comment" in openEHR-EHR-OBSERVATION.blood_pressure.v1: > >> - a non-empty string with the comment on blood pressure measurement. > >> - an empty string, meaning that no comment has been given from the > >> doctor, > >> because not needed (doctor judges that no comment is necessary) > >> - a null value, meaning that no comment has been asked to the doctor, > >> because exluded from the template/GUI. > >> Or there are an other way to model these three cases? > >> > >> Regards, > >> leo > >> > >> > >> > >> Ian McNicoll-3 wrote: > >> > > >> > Hi Leo, > >> > > >> > An important principle under-pinning openEHR is that 'empty' data is > >> not > >> > normally recorded, which is consistent with general clinical practice > >> > information recording. > >> > > >> > On this basis, I am not sure I can see the use case for recording "" > >> i.e. > >> > Empty text. If a text data entry field is left blank, this would > simply > >> > not > >> > be recorded in openEHR data. If the field is mandatory, either the > user > >> is > >> > forced to make some sort of entry or perhaps is allowed to select one > >> of > >> > the > >> > null values as you suggest. > >> > > >> > Regards, > >> > > >> > Ian > >> > > >> > Dr Ian McNicoll > >> > office / fax +44(0)141 560 4657 > >> > mobile +44 (0)775 209 7859 > >> > skype ianmcnicoll > >> > ian.mcnicoll at oceaninformatics.com > >> > ian at mcmi.co.uk > >> > > >> > Clinical Analyst Ocean Informatics openEHR Archetype Editorial Group > >> > Member BCS Primary Health Care SG Group www.phcsg.org / BCS Health > >> > Scotland > >> > > >> > > >> > > >> > On 25 June 2010 16:07, Moretti Leonardo <lmoretti at noemalife.com> > wrote: > >> > > >> >> In > >> >> > >> http://www.openehr.org/releases/1.0.2/architecture/rm/data_types_im.pdf > >> , > >> >> DV_TEXT is defined as a text item. Among "Invariants" (page 29), I > >> found > >> >> that this data type is valid if it is not empty (Value_valid: value > /= > >> >> void and then not value.is_empty and then not(value.has(CR) or > >> >> value.has(LF))). > >> >> > >> >> Does this mean empty string is not a valid value for DV_TEXT? If so, > >> why > >> >> empty string cannot be a valid value? An empty string could be > >> >> meaningful, with a different semantic than null value! Many textual > >> >> information could be an empty string (comments, descritpions..). An > >> >> empty string means that the value is exactly a void string, a null > >> value > >> >> means that the information is unknown, not taken, not asked! > >> >> > >> >> Regards > >> >> leo > >> >> > >> >> _______________________________________________ > >> >> openEHR-technical mailing list > >> >> openEHR-technical at openehr.org > >> >> http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > >> >> > >> > > >> > _______________________________________________ > >> > openEHR-technical mailing list > >> > openEHR-technical at openehr.org > >> > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > >> > > >> > > >> > >> -- > >> View this message in context: > >> http://old.nabble.com/Empty-string-for-DV_TEXT-tp28993527p29022604.html > >> Sent from the openehr-technical mailing list archive at Nabble.com. > >> > >> _______________________________________________ > >> openEHR-technical mailing list > >> openEHR-technical at openehr.org > >> http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > >> > > > > _______________________________________________ > > openEHR-technical mailing list > > openEHR-technical at openehr.org > > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > > > > > > -- > View this message in context: > http://old.nabble.com/Empty-string-for-DV_TEXT-tp28993527p29023384.html > Sent from the openehr-technical mailing list archive at Nabble.com. > > _______________________________________________ > openEHR-technical mailing list > openEHR-technical at openehr.org > http://lists.chime.ucl.ac.uk/mailman/listinfo/openehr-technical > -------------- next part -------------- An HTML attachment was scrubbed... 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