Glaucoma severity / staging

Hi Elaine Wooler - since the last Eye Care CRG, I've been discussing further with Anthony Khawaja options to best handle SNOMED coding of glaucoma severity / staging. 

At the last meeting we presented a couple of well known glaucoma staging systems (the Hodapp-Anderson-Parrish staging system and the ICD-9 classification system) and discussed the merits as well as potential issues of both.

We were previously considering post-co-ordination for glaucoma severity, however are now wondering if disease severity is probably best thought of as an entity in its own right and noted that on the SNOMED browser, "Staging and Scales" have already been separated out from clinical findings and diagnoses:

We would therefore value your advice as to if this might be the way to go? It would potentially allow the use multiple glaucoma staging systems that each relate to a list of glaucoma SNOMED diagnosis terms that are valid for the staging system in question. Thanks

The problems with having glaucoma severity as a post-coordination of a diagnosis are:

• Severity changes over time but glaucoma diagnosis largely does not - mild POAG becomes moderate POAG etc
• Changing diagnoses over time may be clunky
• There are multiple staging systems for glaucoma. 

Might we be able to have glaucoma stage as an observable, e.g. like IOP?  It can have a method (i.e. the grading system), and then a datetime of the assessment.  The severity can change according to the datetime it was assessed and the classification system used, like IOP can change over time and by the measurement device.

Thanks! 

Thanks Anthony Khawaja and Ian Rodrigues 

Yes I was thinking an observable could work here with the staging represented in "Staging and Scales" and used as the technique for modelling the observable.  Leave it with me to work this through.

Hi Ian Rodrigues and Anthony Khawaja 

The images didn't come across.

I have found this for the HPA - let me know if this is an accurate representation, I can't access the original article it was specified in. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2760888/#:~:text=The%20H%2DP%2DA%20classification%20system%20is,2%2C%20SITA%2DSTANDARD%20test.

I can see this link for ICD-9 but these use additional digits to qualify and when I look at ICD-11 this staging seems to have disappeared.

https://www.aao.org/assets/68cdbc7d-35ba-47ce-b95e-726eb503fe3e/635577092075270000/how-to-code-for-different-stages-of-glaucoma-using-icd-10-codes-pdf?inline=1

I have authored the content with an aim to publish in December.

We have an observable as discussed:

• Glaucoma stage (observable entity)
  • Glaucoma stage of right eye (observable entity)
  • Glaucoma stage of left eye (observable entity)

The staging systems in the staging scale hierarchy:

• Hodapp Parish Anderson glaucoma staging system (staging scale)
• International Classification of Diseases 10th Revision glaucoma staging system (staging scale)

The values for each system:

• Hodapp Parish Anderson glaucoma stage - early defect (qualifier value)
• Hodapp Parish Anderson glaucoma staging - moderate defect (qualifier value)
• Hodapp Parish Anderson glaucoma staging - severe defect (qualifier value)
• International Classification of Diseases 10th Revision glaucoma stage 1 - mild (qualifier value)
• International Classification of Diseases 10th Revision glaucoma stage 2 - moderate (qualifier value)
• International Classification of Diseases 10th Revision glaucoma stage 3 - severe (qualifier value)
• International Classification of Diseases 10th Revision glaucoma stage 4 - indeterminate (qualifier value

Can I confirm with you that there are no copyright issues with the HPA system?