is hard to do (Why?)

John Madden

SNOMED/Duke University

Sharing healthcare meaning

A big, recurring mistake

If you can’t specify what sorts of things you’ll be wanting to say…

…you’re unlikely to come up with a good language for saying it.

What do M.D.’s want to do/say?• Store records

retrievably• Ad hoc search• Explore/mine records• Support M.D.-machine

interaction (structured reporting, templates)

• Decision support• Artificial medical

intelligence

Okay

Oy vay

We constantly and unconsciously hop heterogeneous levels of

abstraction !

“The Facts”

“Which facts belong in discharge plan?”

“Hmm, odd combination of symptoms!”

“Which facts belong in an eye exam note?”

Germ Theory of Disease

Why is this a problem?

•Specific, relatively tractable notion of semantics underlies many very successful knowledge representation formalisms• “The existence and non-existence of

atomic facts is Reality.…A proposition presents the existence and non-existence of atomic facts.”

•“Of what we cannot speak, we must remain silent.”

But what’s missing?

•Context

•Relevance

•Agendas

•Workflow embedding

•Paraconsistency

Three topologies for “semantic interoperability”

Central semantic authority

What happens?

“If you would just our controlled vocabulary (damn it), we wouldn’t have all these interoperability issues.

Spheres of Influence

•De facto interoperabiltiy

• Inferencing is tractable

•Maintenance is conceptually simple

Pro and con• Terminological

complexity scales poorly

• Inferencing is brittle

• Restricts speech

• Maintenance (in practice) incredibly laborious

Hierachical semantics

Very specific butpoorly sharable

Devoid of specificsbut very sharable

What happens?

•Centralized terminologies ‘lose weight”

•Users take on more responsibility

• “Weakest link” phenomenon

What happens?

Registries

Ontology rconciliation

Pro and con

• Unrecoverable loss of information

• Inconsistencies still break inferences• And now they

might be harder to pinpoint

• Can still reason• And maybe the

size of the fact base is smaller and more manageable

Federated semantics

• Mapping•Responsibility is finely

divided•Quality depends on peer-

to-peer collaboration• “Map-to-play”

• Few global guarantees• Need to support a

“market” in ontology fragments

What happens?

Nirvana

•Locally consistent

•Globally tolerant of inconsistency

•Finely granular in either case

At what level are we non-interoperable?

“The Facts”

“Which facts belong in discharge plan?”

“Unusual combination of symptoms!”

“Which facts belong in my exam note?”

Germ Theory of Disease

Technology fit to use case

Heavy inferencingHeavy search

Very contextual

Very non-contextual