Process Overview for Submitting New Condition Codes to SNOMED International: A Use Case in Retina

Article initiated by:

Fritz Gerald P. Kalaw, MD

All authors and contributors:

Sally L. Baxter, MD, MSc, Cindy Cai, Fritz Gerald P. Kalaw, MD

Assigned editor:

Review:

Assigned status Update Pending

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Representation of ophthalmic conditions in standardized terminologies is critically important for data harmonization and defining relevant disease cohorts for research studies. In this article, we provide an overview of the process of submitting new condition codes to SNOMED International. To provide specific examples, we will leverage a recent use case in retina condition codes that were identified to be missing based on a systematic analysis of the Ryan’s Retina textbook.

Background and identification of an information source

One of the complex subspecialties in ophthalmology is the field of retina. Continuous research, technological advancement, and updated surgical techniques paved the way for the creation of Ryan’s Retina textbook. Ryan’s Retina is a highly regarded source of knowledge in diagnosing and managing diseases in the retina and vitreous. Originally published in 1989, Ryan’s Retina has continuously updated its contents, covering the basic science until surgical management of vitreoretinal diseases. Its latest edition, the 7th, was published in the year 2023, with over 300 contributors worldwide and over 2,800 pages, making it one of the most comprehensive references available on retina today.

Summary workflow of submission of new retina concepts to SNOMED International.

Identification of relevant clinical concepts

The Retina Observational Medical Outcomes Partnership (OMOP) Subgroup, which is part of the Eye Care and Vision Research OMOP Workgroup, initiated a review of all diagnoses discussed in Ryan’s Retina 7th edition textbook. The diagnoses were identified from each chapter outline, free text, and index terms to capture all diagnoses from the textbook.

Identification of gaps in representation

The diagnoses were then tabulated and mapped against the Athena Observational Health Data Sciences and Informatics (OHDSI) web browser to look for gaps in representation from the Systematized Nomenclature of Medicine (SNOMED).

SNOMED is considered one of the most comprehensive clinical terminologies in the world and has been recommended by the American Academy of Ophthalmology as the terminology of choice for representing clinical concepts. The Athena OHDSI browser is an online repository of medical vocabularies that underlies the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM), which delineates a standard structure and vocabulary and is commonly used in healthcare databases, such as the Veterans Affairs Million Veterans Program, the NIH All of Us Research Program, and the National Covid Cohort Collaborative.

The mapped concepts were matched according to the adequacy of the terminology: Complete match when a concept code mapping was represented equally as the source diagnosis, Partial match when the concept code had a broader terminology characterization, or the concept code fulfilled the source diagnosis but with an additional specification, and No match when the concept was missing or not available from the SNOMED terminology.

Consultation with specialists

Diagnoses identified from the Ryan’s Retina textbook with no matching concepts from SNOMED were submitted to retinal specialists within the Retina OMOP Subgroup using Qualtrics, an online survey platform. The diagnoses were rated according to their importance: important, somewhat important, and not important. This aimed to inform prioritization of the codes for submission. All diagnoses rated as important were discussed in separate meetings, and members of the Retina OMOP Subgroup established an agreement for suggestions to the SNOMED International group.

A total of 327 diagnoses were identified; 231 had complete match, 63 partial match, and 33 no match. Of the 33 diagnoses with no matching concepts, consensus from the Retina OMOP Subgroup agreed that 11 of the diagnoses should have a definite term or condition code defined in SNOMED. The full details of what was submitted to SNOMED are described in the Appendix. These consisted of the following diagnoses:

1. Nonexudative neovascular age-related macular degeneration

2. Paracentral acute middle maculopathy

3. Glaucoma drainage implant endophthalmitis

4. Lamellar macular hole

5. Nonproliferative sickle retinopathy

6. Submacular hemorrhage

7. Choroidal granuloma

8. Pachychoroid neovasculopathy

9. Pachychoroid pigment epitheliopathy

10. Peripheral exudative hemorrhagic chorioretinopathy

11. Nongeographic atrophy

Submission to SNOMED

Proposed condition codes were discussed at an Eye Clinical Reference Group (CRG) meeting of SNOMED International. Members of the Eye CRG agreed on the utility of the proposed codes, representing international agreement, given that multiple countries were represented in the Eye CRG.

A written list of proposed condition codes was then submitted via the Confluence page for the Eye CRG. In addition to the condition names themselves, SNOMED also requested ICD-10 codes available, definitions for each of the conditions, and examples of peer-reviewed literature discussing the condition, which the Retina OMOP Subgroup subsequently provided. The SNOMED staff team examined for any representation among existing codes and asked clarifying questions regarding the mappings and hierarchies, which Eye CRG members answered.

Release of new concepts

Finally, after resolving questions, the new condition codes were developed in SNOMED, including fully specified names (FSNs), preferred terms, and concept identification numbers. These were scheduled for full release with the next update of SNOMED International.

Related EyeWiki Pages

Data Standards in Eye Care

Appendix

List of diagnosis, definition, and literature review submitted and proposed for inclusion to SNOMED code.

1. Nonexudative neovascular age-related macular degeneration

ICD-10 / ICD-10-CM code: none

Definition/Description: Nonexudative (or quiescent or asymptomatic) MNV is defined as treatment-naïve type 1 neovascularization detected with dye-based angiography or OCTA that is not associated with clinical evidence of exudation.

Literature review:

https://doi.org/10.1016/j.ophtha.2020.01.040 (Ophthalmology)

https://doi.org/10.1016/j.oret.2020.02.016 (Ophthalmology Retina)

DOI: 10.1097/IAE.0000000000003598 (Retina)

2. Paracentral acute middle maculopathy

ICD-10 / ICD-10-CM code: none SNOMED Code: 1222665003 (May 2022) – not found in Athena OHDSI platform

Definition/Description: An ischemic lesion caused by impaired perfusion of deep retinal vascular complex.

Literature review:

https://doi.org/10.1016/j.ophtha.2018.07.006 (Ophthalmology)

https://doi.org/10.1016/j.oret.2021.01.003 (Ophthalmology Retina)

DOI: 10.1097/IAE.0000000000003339 (Retina)

3. Glaucoma drainage implant endophthalmitis

ICD-10 / ICD-10-CM code: none

Definition/Description: In most cases of endophthalmitis related to GDI, there is tube exposure present with injected conjunctiva, purulence from the implant site and hypopyon.

Literature review:

DOI: 10.1097/IAE.0000000000001329 (Retina)

doi: 10.1038/s41433-021-01462-9 (Eye)

4. Lamellar macular hole

ICD-10 / ICD-10-CM code: none

Definition/Description: Thinning of the foveal tissue, leaving the RPE and photoreceptor layers intact but causing partial loss of the inner nuclear layer

Literature review:

https://doi.org/10.1016/j.ophtha.2014.10.014 (Ophthalmology)

https://doi.org/10.1016/j.oret.2022.07.009 (Ophthalmology Retina)

DOI: 10.1097/IAE.0000000000003665 (Retina)

5. Nonproliferative sickle retinopathy

ICD-10 / ICD-10-CM code: none

Definition/Description: The retinal changes in NPSR occur secondary to vaso-occlusion and local ischemia. Occlusion of retinal vasculature first appears in the peripheral retina as “salmon patches”, which represent retinal hemorrhage from superficial blood vessels.

Literature review: DOI: 10.1097/IAE.0000000000000309 (Retina)

10.1016/j.ajoc.2022.101329 (American Journal of Ophthalmology Case Reports)

6. Submacular hemorrhage ICD-10 / ICD-10-CM code: none

Definition/Description: Subretinal hemorrhage is an accumulation of blood between the neurosensory retina and the Retinal Pigment Epithelium (RPE) arising from the choroidal or retinal circulation

Literature review: https://doi.org/10.1016/j.ophtha.2016.01.035 (Ophthalmology)

https://doi.org/10.1016/j.oret.2020.07.028 (Ophthalmology Retina)

DOI: 10.1097/IAE.0000000000003725 (Retina)

7. Choroidal granuloma

ICD-10 / ICD-10-CM code: none

Definition/Description: Granulomas are nodular collection of immune cells formed by the immune system to confine pathogens and inflammatory agents that cannot be eliminated.

Literature review:

DOI: 10.1097/IAE.0000000000002864 (Retina)

10.3390/diagnostics13071296 (Diagnostics)

8. Pachychoroid neovasculopathy

ICD-10 / ICD-10-CM code: none

Definition/Description: Described the occurrence of type 1 MNV lacking aneurysmal dilations (polyps) in eyes with pachychoroid disease

Literature review:

https://doi.org/10.1016/j.ophtha.2016.06.060 (Ophthalmology)

https://doi.org/10.1016/j.oret.2022.04.004 (Ophthalmology Retina)

DOI: 10.1097/IAE.0000000000002980 (Retina)

9. Pachychoroid pigment epitheliopathy

ICD-10 / ICD-10-CM code: none

Definition/Description: Characterized by the presence of RPE disruption within the posterior pole over regions of choroidal thickening in eyes showing no evidence of active or prior CSC

Literature review:

DOI: 10.1097/IAE.0000000000001773 (Retina)

10.1136/bjo-2022-322457 (British Journal of Ophthalmology)

10. Peripheral exudative hemorrhagic chorioretinopathy

ICD-10 / ICD-10-CM code: none

Definition/Description: Uncommon degenerative process of the retina with subretinal or sub-RPE hemorrhage and exudative mass outside of the macular region

Literature review:

DOI: 10.1097/IAE.0000000000003636 (Retina)

10.3760/cma.j.cn112142-20221024-00527 (Chinese Journal of Ophthalmology)

11. Nongeographic atrophy

ICD-10 / ICD-10-CM code: none

Definition/Description: May be thought of as incipient atrophy as it may immediately precede GA in the same location | (other definition from a paper) Nongeographic atrophy was defined as retinal pigment disturbances including hypopigmentation and hyperpigmentation in CFPs that typically corresponded to hyperfluorescence and hypofluorescence in FA images within or overlapping areas previously occupied by CNV.

Literature review:

https://doi.org/10.1016/j.ophtha.2018.11.020 (Ophthalmology)

10.1001/jamaophthalmol.2020.0437 (Journal of American Medical Association Ophthalmology)