The Guilty, the Innocent, and the SNOMED Shuffle

Attributes in transition

Currently accepted attributes

Causative agent

Associated etiologic finding

Temporally follows

Causative agent

Asserts A definitely caused by B

Accepts as values: Organisms Substances Physical forces

ExamplesLeprosy

Causative agent Mycobacterium leprae

Polybrominated biphenyl poisoningCausative agent Polybrominated

biphenyl

High altitude cerebral edemaCausative agent Low air pressureCausative agent High altitude

Associated etiologic finding

Also asserts A definitely caused by B

Accepts as values Findings Disorders

Examples:

Graft failure due to thrombosis Associated etiologic finding Thrombosis

Iron deficiency anemia Associated etiologic finding Iron

deficiency

Temporally follows

Asserts that A occurred after B Neither asserts nor excludes causal

relationship between A and B Accepts as values

Findings Disorders Procedures

Examples

Post-measles encephalitis Temporally follows Measles

Post-operative hemorrhage Temporally follows Surgical procedure

Problems and limitations:

Causality vs. association not always clear

Confusion between Associated etiologic finding and Temporally follows

Lack of generic “associated with” attribute

Cannot define a procedure as cause of a disorder or finding

Causality attributes appropriate if:

A is known to be caused by B Causality keywords:

due to caused by induced by resulting from

Ambiguous associations

Causality unclear in many cases Keywords:

associated with in with modified by during complicating secondary to

So how do I say: “A associated with B” ?

Use Temporally follows (old solution)

Use Associated with (proposed new solution)

DON’T! (preferred solution)

Temporally follows = associated with?

PRO Previously recommended Uses existing attribute

CON A and B may occur simultaneously Loss of “A POST B” as distinct meaning

Associated with

Proposed new attribute Neither asserts nor excludes causality Would be parent of:

Causative agent Associated etiologic finding Temporally follows

Associated with

Pro: Unambiguous way to express ambiguous

associations

Con Not yet accepted Potential overlap with Temporally follows

Proposed use of Associated with:

Will be used to express A + B without specifying nature of relationship between A and B

Examples: Tuberculosis in pregnancy AIDS with pneumonia

Why bother?

Good question!

We DO NOT recommend using “Associated with” to post-coordinate concepts

If you cannot specify the nature of the relationship between two concepts, do not conjoin them

Enter as separate diagnoses or findings

Temporally follows vs. Associated with:

Potential overlap Both concepts neither assert nor exclude

causality Temporally follows has been previously

used to mean “associated with” Proposed new attribute hierarchy does

not clearly define distinction between Temporally follows (may become “Sequela of”) and Associated with in use.

Temporally follows vs. Associated etiologic finding

If A caused B, then by definition B preceded A (if only by a nanosecond). The lag in time between A and B, however, is often inapparent or insignificant.

Associated etiologic finding stresses causality

Temporally follows stresses time sequence

Proposed guideline:

Use Temporally follows only when A necessarily follows B by a clinical significant period of time.

Keywords: after following post subsequent to

Example 1

Post-viral encephalitisTemporally follows Viral infection

Occurs after resolution of viral infectionCompare to: Viral encephalitis

Causative agent Virus

Example 2

Post-operative hemorrhageTemporally follows Surgical procedure

Compare to:Intra-operative hemorrhage

Associated with Surgical procedure

Example 3

Post-streptococcal glomerulonephritisTemporally follows Streptococcal infection

Associated etiologic finding Streptococcal infection

If association is BOTH temporal and causal, both attributes are used.