# how to determine that a variable has PQ according to ISO 21090 **Category:** [Clinical (archive)](https://discourse.openehr.org/c/clinical-archive/153) **Created:** 2009-02-05 14:07 UTC **Views:** 10 **Replies:** 5 **URL:** https://discourse.openehr.org/t/how-to-determine-that-a-variable-has-pq-according-to-iso-21090/14876 --- ## Post #1 by @williamtfgoossen Dear all, We are currently working on several archetypes and encounter difficulties in finding the right approach in the Ocean archetype editor. For instance, a pain scale (VAS type, or numeric 0 -10). According to ISO datatypes 21090 this is a Physical Quantity. How can this be determined in the editor? We get the option Q to set that it is a quantity. Then there is a wealth of specific units, but not a simple way of stating this is a PQ. Am I missing the point here? Sincerely yours, dr. William TF Goossen director Results 4 Care b.v. De Stinse 15 3823 VM Amersfoort the Netherlands email: Results4Care@cs.com phone + 31654614458 fax +3133 2570169 www.results4care.nl Dutch Chamber of Commerce number: 32133713 --- ## Post #2 by @ian.mcnicoll Hi William, Have a look in CKM at CLUSTER\.Symptom\-pain \[Pain symptom\] Under Current Intensity ,a numeric 0\-10 pain scale, is modelled as a Count, since Pain scale has no agreed international physical units\. Count and Quantity are both sub\-classes of Amount in the openEHR ref model but for Quantity, the units attribute is mandatory \(UCUM units\)\. I see mention of a 'standard 10cm\. VAS' \. In this case, it could be modelled as a Quantity, property type Length Units cm\. This element could be included in the archetype alongside the Count element, but I am not sure that the physical length has any particular significance and this may just be over\-complicating the model\. e\.g Would a 'large\-print' 20cm scale with 10\*2cm intervals not be equivalent? This was an interesting find via Google \-summary of pain scales http://www.clinicalinfometrics.northwestern.edu/archive/Tab%208%20Pain%20Measures.pdf Regards, Ian PS Derek Hoy tells me you will be over in Scotland in the near future\. It would be nice to meet up and say hello\. --- ## Post #3 by @system Hi William I guess the point here is model what clinicians want and understand. I do not think that pain scales have any idea of ‘cms’ – so units does not seem appropriate. If you want a real with no units, you can use ‘qualified real’ property which allows a blank unit. Cheers, Sam --- ## Post #4 by @williamtfgoossen In a message dated 8-2-2009 4:47:16 W. Europe Standard Time, sam.heard@oceaninformatics.com writes: > Hi William > > I guess the point here is model what clinicians want and understand. I do not think that pain scales have any idea of ‘cms’ – so units does not seem appropriate. > > If you want a real with no units, you can use ‘qualified real’ property which allows a blank unit. > > Cheers, Sam Thank you Sam, This is helpful. One addition to this: is the definition of real also allowing a score on the VAS of say 4.5? So decimals? Some pain scales use the numeric values 0 - 1 - 2 till 10 (the numeric score variant), but others allow setting a cross on a 10 cm line and then the actual score is determined allowing decimals. Sincerely yours, dr. William TF Goossen director Results 4 Care b.v. De Stinse 15 3823 VM Amersfoort the Netherlands email: Results4Care@cs.com phone + 31654614458 fax +3133 2570169 www.results4care.nl Dutch Chamber of Commerce number: 32133713 --- ## Post #5 by @williamtfgoossen Hi Sam, We have tried, but it is not possible to represent a proper VAS scale in the archetype editor. What clinicians want is exactly as I said before: being able to score a 5, 7, 10 for pain. This looks like the above instrument in this picture.

But as you can see in some instance the patient will say, my pain today is like a 7.3 or a 3.6 or a 9.9 The qualified Real does not deal with it. So it appears not possible to handle the ISO 21090 PQ datatype which would allow to have a decimal. Further the qualified real does not allow to set the minimum 0 and maximum 10 score. If we apply the valid and reliable McGrath for pediatrics, we see the five level faces, where 5 is obvious the :-( sign (much pain) and the 1 is :-) (no pain) This would really be an ordinal, but stored with a number. For this one the qualified real would do. So we do experience difficulties in using the archetype editor to proper represent clinical and scientific knowledge. Hope you can find a solution for this. Thanks William In a message dated 8-2-2009 4:47:16 W. Europe Standard Time, sam.heard@oceaninformatics.com writes: > Hi William > > I guess the point here is model what clinicians want and understand. I do not think that pain scales have any idea of ‘cms’ – so units does not seem appropriate. > > If you want a real with no units, you can use ‘qualified real’ property which allows a blank unit. > > Cheers, Sam > > **From:** openehr-clinical-bounces@openehr.org [mailto:openehr-clinical-bounces@openehr.org] **On Behalf Of** Williamtfgoossen@cs.com > **Sent:** Thursday, 5 February 2009 11:38 PM > **To:** openehr-clinical@openehr.org > **Subject:** how to determine that a variable has PQ according to ISO 21090 > > Dear all, > > We are currently working on several archetypes and encounter difficulties in finding the right approach in the Ocean archetype editor. > > For instance, a pain scale (VAS type, or numeric 0 -10). According to ISO datatypes 21090 this is a Physical Quantity. > > How can this be determined in the editor? We get the option Q to set that it is a quantity. Then there is a wealth of specific units, but not a simple way of stating this is a PQ. > > Am I missing the point here? > > Sincerely yours, > > dr. William TF Goossen > director > Results 4 Care b.v. > De Stinse 15 > 3823 VM Amersfoort > the Netherlands > email: Results4Care@cs.com > phone + 31654614458 > fax +3133 2570169 > www.results4care.nl > Dutch Chamber of Commerce number: 32133713 Sincerely yours, dr. William TF Goossen director Results 4 Care b.v. De Stinse 15 3823 VM Amersfoort the Netherlands emails: Results4Care@cs.com williamtfgoossen@cs.com info@results4care.nl phone + 31654614458 fax +3133 2570169 www.results4care.nl Dutch Chamber of Commerce number: 32133713 --- ## Post #6 by @system Hi William I am not sure of the requirements but I think you want a real number between 0 and 10. You are right that there is a bug in Qualified Real that does not allow you to set a max and min value (this has been added to Jira). The most correct way to deal with this is as a proportion (on the grounds that a real number on its own in medicine is a ratio or proportion of some kind). This needs to be unitary (ie denominator of 1). The ADL looks like: ELEMENT[at0005] occurrences matches {0..1} matches { -- Pain value matches { DV_PROPORTION matches { numerator matches {|0.0..10.0|} type matches {1} } } } Hope this is helpful and thanks for finding the problem with the qualified real. Cheers, Sam [details="(attachments)"] ![Untitled01.jpg|500x209](upload://aG3JGvIwAZl7dRk4NFif7VCpH9o.jpeg) [/details] --- **Canonical:** https://discourse.openehr.org/t/how-to-determine-that-a-variable-has-pq-according-to-iso-21090/14876 **Original content:** https://discourse.openehr.org/t/how-to-determine-that-a-variable-has-pq-according-to-iso-21090/14876