SNOMED for Clinical Records:

Tools to facilitate implementation.

Jeff R. Wilcke, DVM, MS, DACVCP

AVMA Liaison to the

SNOMED Editorial Board

Conflicting Goals

• Store medical information in a way that optimizes retrieval.

• Allow a range of expressive capability– Acute, chronic, subacute– Left, right, both…– Tentative, final, rule-out (diagnoses)

What do we need?

• A manageable list of concepts.– simplifies data entry– Technical expressiveness of Fun with Dick and Jane

• Nomenclature / Vocabulary / Classification – We can be CERTAIN that the “term” (description in

SNOMED) means what we think it means.– We can develop rules that allow us to combine concepts

to express ideas more complicated than those contained in the nomenclature.

– Volume and technical sophistication of War and Peace

How much is enough?

SNOMED

“Veterinary” SNOMED

“Companion Animal”SNOMED

“Equine” SNOMED

Which part do we need?

Companion Animal

SNOMED

FoodAnimal

SNOMED

SNOMED Strategies

• Keep the lists small, restrict “freedom of expression”– Keep the tools simple and inexpensive– Make the learning curve steep and short– Limit the long-term uses of data

• Make the lists inclusive, facilitate expression.– Spend system $$$ for vocabulary activity– Build flexibility into user interface tools (and make

the user spend more time on data entry).– Capture “future value” in data sets

Intermediate Strategy

• Keep the interface “pick-list” restricted

• Allow the user to have access to SNOMED as needed (add new concepts to “pick-list”)

• Create a strategy for “concept building.”– Also called post-coordination– Not a simple notion

Implementing SNOMED

• “Recipe” for SNOMED subsets available.• Cannot be completely automated

– Our subset is a “horizontal slice” through SNOMED.

– Algorithms like “find all descendants” of a concept• very powerful, not very selective.

• Only function in the “vertical”

– Can allow user interaction to customize-with-use

• Person=power to produce subsets– between limited and unavailable.

The root hierarchies of SNOMED are displayed. ANY SNOMED concept can be selected as the root of a custom hierarchy by following text links.

This page is was reached by Selecting the “Disease” link, then “Disease by Body Site”.

Clicking a “Select as Root” button opens this page.

At this point, clicking the individual nodes modifies the content of a window to the right (automatically).

Selecting “Disease of cardiovascular system displays its children. “Heart disease” and “Vascular disease” are selected for the next level. Click “Add checked nodes”.

In this mode, nodes can be deleted by selecting the delete key or additional nodes can be added from those that remain un-selected. (Tree was refreshed after the selections were added.)

The process has been repeated for several nodes and through several generations.

While in the build mode, any node selected on the tree offers an opportunity to add to or delete from its children.

In “Maintenance Mode,” you can raise a node to a higher level in the “Is A” hierarchy. Everything is a child of cardiovascular disease.

In “Maintenance Mode,” you can substitute a synonym for a concept. Once selected, the synonym will be displayed in the tree.

Post-coordination Issues

• Data structure is parallel to SNOMED native.– Single table approach

• Additional field minimum to account for “instances”

• Maintain fidelity with active copy of SNOMED for searching, phrase construction.

– Multi-table approaches (child, grandchild) are used in this simulation

– Can be used to generate phrase represented by a link to a local code. SNOMED encoded phrase is searched, or communicated.

Select the unfinished Visit for “Hokie”, case 123460

Add Body Weight, then Add Finding

Search SNOMED link connects to custom browser element. Search for “fracture and femur”.

Select “Closed fracture of femur”

Refresh summary screen.

Select code [phrase] link to modify.

SNOMED link as before, frequently used codes for Severity, laterality, certainty, etc.

Select either link to modify the concept indicated. EitherParents or children may acquire additional children.

Currently laterality is the only available modifier for children (others may be appropriate, we’re not prepared to judge). In this case it modifies the root (parent) concept.

The “frequently used codes” list.

This is the diagnosis in display/select mode, only the root (parent) concept is visible. When you select an observation value, you are shown its full storage form.

Real purpose of this application:

• The demo records system is also linked to an HL-7 based report generator.

• XML Reports