Miscellaneous questions, attempted answers

Topic 1: “Composite” procedures

Q: Some procedures consist of several separate sub-procedures. If SNOMED has concepts for the individual procedures, how do we link them?

A: You can’t. But your medical record system potentially could.

Huh?

SNOMED has no attribute allowing a post-coordinated link between multiple procedures to express that they are performed (and billed) as a single diagnostic or therapeutic procedure consisting of multiple steps

Implementation problem => implementation solution?

Now what?

Enter separate codes for each part of the composite procedure

Request a pre-coordinated concept for the composite procedure

Pursue implementation solution?

Example 1:

Treadmill exam for roarers

Coders have been using: Laryngoscopy P1-25700 Use of treadmill P7-40460

Exactly what is this?

Diagnostic procedure consisting of exercise on treadmill followed by laryngoscopy to evaluate laryngeal function to rule in/rule out partial or complete laryngeal paralysis (“roarer”)

Problems with existing approach:

Laryngoscopy P1-25700 is not defined as a diagnostic procedure (includes therapeutic laryngoscopy as well)

Use of treadmill P7-40460 is defined specifically as therapeutic

ISA Physiotherapy class activitiesISA Physical therapy procedure

Option 1:

Option 1: Enter separate but more specific procedures to capture more information:

Progressive exercise test on treadmill Diagnostic laryngoscopy Laryngeal function studies

Has method Patient evaluation Has procedure site Laryngeal structure Has intent Diagnostic intent

Option 2 (better):

Request new concept, to be defined as:

Treadmill exercise test and laryngoscopy to evaluate laryngeal function

ISA Progressive exercise test on treadmill

ISA Diagnostic laryngoscopyISA Laryngeal function studies

Caveat:

Do not attempt to post-coordinate (nor will we pre-coordinate) “Roarer” to this procedure

The object of the evaluation is laryngeal function, not a specific diagnosis which may or may not be present

Example 2

Radiation therapy—palliative

Coders have been using: Radiation therapy procedure or service Palliative care

Exactly what is this?

Radiotherapy with a particular intent (to palliate rather than to cure the condition being treated)

Problems with existing approach:

Palliative radiotherapy is not a composite procedure, but a single procedure with a particular intent (palliation)

Using a second procedure Palliative care does not specify that the intent of the radiotherapy is palliative

Solution:

In this case, SNOMED already contains an appropriate pre-coordinated concept:

Palliative course of radiotherapy 168528

What if it didn’t?

Can post-coordinate the “intent” of a procedure using approved attribute

Has Intent. Approved values = subtypes of Intents (only!): Diagnostic intent Palliative intent Preventative intent Screening intent Therapeutic

Example 3

Vaccination with Equine Mystique II

Coders have been using: Animal immunization for rabies Veterinary immunization procedure Ehrlichia risticii bacterin (product)

Exactly what is this?

Administration of a particular brand-name vaccine containing inactivated rabies vaccine and Ehrlichia risticil bacterin

This is a SINGLE procedure in which two immunizing substances are administered

Problems with existing approach:

Veterinary immunization procedure is properly only a navigational, not defining, concept

Ehrlichia risticii bacterin not linked to any “administration” procedure

Only substances, not products, can be linked to ANY procedure. Substances are linked as active ingredients to products containing them.

Solution:

Immunization procedure +Direct substance Rabies antigen

(substance)Direct substance Ehrlichia risticii bacterin

(substance)

Note: this is our preferred approach to ALL immunization procedures. Such construction should be stored in your systems as “local pre-coordinations” ---ie,an extension of SNOMED.

Example 4:

Ventral basket stabilization (cervical)

Coders using: Cervical arthrodesis by anterior technique

(procedure) Spinal fusion with graft (procedure)

Exactly what is this?

Fusion of cervical vertebrae by anterior technique using a “spinal basket” (also known as a “spinal cage”).

Problems with existing approach:

Device used (basket or cage) not captured

Spinal fusion with graft is specifically defined as a bone graft

Site of Spinal fusion with graft not specified as cervical

Solution

Cervical arthrodesis by anterior techniqueDirect device Spinal cage

Note: can request creation of this as a pre-coordinated concept

Topic 2: Procedure vs. action/access

Q: Do we need to use a concept defined as a “Procedure” to code a procedure or can we use a concept defined as an “Action” or “Access”?

A: You MUST use a procedure

What if the procedure isn’t in SNOMED… but the “action” is?

Request a new procedure concept

Choose the closest appropriate procedure concept and post-coordinate

Has method [action] Access [access]

Caveat: use approved values ONLY

Approved values for Has method: Subtypes of Action 129264002

Approved values for Access: Subtypes of Surgical access values

309795001

Danger, Will Robinson!

Make sure the procedure you choose contains nothing in its definition that is NOT true of the procedure you are coding

PLEASE contact us for guidance on post-coordinating actions and accesses as these can be tricky

Topic 3: Morphology vs. Finding/Disorder

Q: When only a morphology concept exists when we want a finding or disorder concept, can we use the morphology as a “diagnosis”?

A: No

Solution:

Request a finding or disorder concept

Choose the nearest appropriate finding or disorder concept and post-coordinatethe specific morphology

Example:

Hydrops (accumulation of fluid in placenta)

User finds no such disorder in SNOMEDbut does find:

Hydrops (morphologic abnormality)

Solution:

Disorder of placentaAssociated morphology Hydrops

Topic 4: Limited classification concepts

Q: When there is only an LC concept to describe a diagnosis what should we do? Use it or submit to forum?

A: Submit it to the forum. These are often “Iimited” for good reason and we may be able to find, or request, a better concept.

Topic 5: Chemotherapy

Q: How do we code chemotherapy, since Chemotherapy procedure

108234007 is not a subtype of General Administration (which is what we use for other drugs?

A: Use Administration of anti-neoplastic agent 363688001

(synonym Chemotherapy)

Topic 6: Neoplasia stages

Q: How can we post-coordinate the “Stage” of a neoplasia?

A: Depends on whom you ask

Approach #1:

Post-coordinate as follows:

Neoplasm X (disorder)Interprets Malignancy stage (observable

entity) Has interpretation: Stage Y

SNOMED is likely to adopt this approach

Approach #2:

Post-coordinate as follows:

Neoplasm XHas staging Stage Y

Jeff prefers this approach (and frankly so do I) BUT…

CLASH OF THE TITANS!

Q: So whose way do we follow?

A: Approach #2 is simpler (and more aesthetically pleasing). But if you implement this approach, you will not be able to exchange data with those who follow the SNOMED-recommended method.

Caveat:

Need to request veterinary staging values as existing staging values are based on human medicine and are not equivalent.

Topic 6: How do we post-coordinate:

Topographic modifiers (distal, proximal) General site descriptors (deep, superficial) Distributions (focal, generalized) Histologic grade of a neoplasm (well-differentiated) Remission phases (partial remission, etc) Certainty of diagnosis (possible, suspect)

A: You can’t. SNOMED has no approved attributes by which these can be post-coordinated

Don’t try this at home

Q: But you’ve got a secret method to post-coordinate this stuff, right?

A: No. We do not know how to do this, we do not recommend doing this, we would not do this, we will not sanction doing this.

Severities: your lucky day

Q: How do we post-coordinate the severity of a disorder?

A: Use Severity (attribute) allowed values for this attribute: subtypes of

Severity of illness (qualifier value)

This is an approved attribute with approved values

Extend yourself…

Record and maintain your post-coordinated concepts for use as a “local extension” of SNOMED, giving them local or internal codes, which may then be entered in your medical records as “concepts” in their own right.

Extension core information

SNOMED has specific mechanisms for assigning concept identifiers in "extensions" (see SNOMED for details)

Extensions are created by users adding their own rows to SNOMED tables (concepts,synonyms and relationships)

The care and feeding of local extensions is the responsibility of their “keepers”

Yes, we have no bananas

SNOMED cannot and should not be expected to supply all the functionality necessary to support infinite granularity in electronic medical records. Adding functionality can exponentially increase complexity and potential for error and must proceed with care.

Use only constructions that SNOMED CAN support.

The role of the medical record

Accuracy and expressivity depend on: the nomenclature

content (vocabulary) syntax (means to connect items in

vocabulary) the medical records system

how much context can it supply?

Context: an example

Mast cell tumor may occur in many contexts:

As a differential diagnosis As a final diagnosis As a previous diagnosis As “family history of”

Pre-coordinated approach to context

Multiple, pre-coordinated concepts: Mast cell--differential diagnosis Mast cell--final diagnosis Mast cell--previous diagnosis Mast cell--family history of

Precoordinated approach

PRO: single code entries

CON: combinatorial explosion limited expressivity

Post-coordinated approach to context

Create and maintain links between core concept and “context” concepts:

Core concept: Mast cell tumor

Context concepts: Differential diagnosis Final diagnosis Previous diagnosis Family history of

Linkage concepts: ??

Post-coordinated approach

PRO: Greater expressivity Fewer concepts required

CON: Requires sophisticated syntax + style guide Requires more sophisticated users Requires permanent links between concepts in

post-coordinated construction

Post-coordination: not as easy as it looks

[mast cell tumor][attribute X] [Family history of]

SNOMED logic makes “Family history of mast cell tumor a subtype of Mast cell tumor => ERROR

[Past medical history of][Associated finding] [Mast cell tumor] ???

Context in the medical record: the nuclear fusion of informatics

Medical records supplies multiple “fields” Differential diagnoses Past history of Family history of Final diagnoses

The nomenclature need then supply only a single concept, Mast cell tumor, to be used in each of these fields