canadian healthcare codes and terminology standards

Healthcare Codes and Terminology Standards

BC Homes,Chief Technologist

Presented in 2012

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HL7 v3 Background


Agenda

» Concepts» Code Data Types» Concept Domains, Code Systems and Value Sets» Implementation Concerns


Opening Salvo

» Codes and Terminology are topics that are easyto introduce, but tricky to understand in full complexity» IT Professionals encounter “codes” all the time

› e-Health’s notion is really no different


Simple Examples

» The classic Canadian example› ‘en’ or ‘fr’

» The most common example› ‘M’ or ‘F’


Ah-ha!

» At one level, we can conclude that there’s reallynothing to this.

› We’ve all seen codes before› What’s the big deal?


Recall one of the Complaints aboutHL7 v2

» Limited rigour in use of controlled vocabularies› Links between standard vocabularies and

message structures are ad-hoc andimplementation specific» As a consequence, HL7v3 spells out a numberof very specific things relating to codes

› Much more rigour› Often very exacting› Still leaves room for Jurisdictions to makedifferent choices


Code Namespaces

» Consider this example:

en


Not necessarily unique

» “en” = English» “en” = Printer’s measure» “en” = ethylenediamine


Key Point

» Context is important» Sometimes context might not be enough

› When we’re dealing with (for example) numeric codes, you can have overlaps

• I don’t know of a clear case where this has happened, but better safe than sorry


OIDs : Like Namespaces for Codes

» Conceptually, you can imagine animplementation of codes in which all valuesexist in one table

› A code is only unique when it is accompanies with an OID› All codes using the same OID are considered to be part of a code system


Example

» English› code = “en”› codeSystem = “2.16.840.1.113883.6.84”

» XML:

<languageCode code="en" codeSystem="2.16.840.1.113883.6.84"/>

» Why does an e-Health system need a language code?

› e.g.: no guarantee that a patient speaks any particular language


Question

» Who decided that “en” stands for English?


Answer

» ISO : International Organization for Standardization» Specifically, the two-letter code for identifying languages is part of ISO standard 639-1

› First created in 1967› Contains 184 codes (languages)


Answer

» We can say, then, that the “meaning” of our OID,2.16.840.1.113883.6.84, is the ISO 639-1 standard

› The “code system” is essentially means a “published standard” (with a defined context)› e.g: ISO 639-1 is a “published standard” to describe “languages” (context of “language”)

» In HL7 terms, the notion of the context is calleda “Concept Domain”

› We’ll say more about this in a bit


The Treachery of OIDs

» Finding the right OID is an extremely tricky exercise

› There are multiple places you can try to look them up. No one source has the complete list› And sometimes they change when you’re not paying attention

• These are “living standards”


Looking Up OIDs


Surprise! Change!

» In the V02R02 standard, the OID for the ISO639-1 was 2.16.840.1.113883.6.84» In the most recently-published standard,R02.04.02, the OID for ISO 639-1 is 1.0.639.2

› What’s more, Canada no longer uses the 2-character language code.

• Rather than “en”, we should use “eng”

» Our important take-away: forget I ever told youabout 2.16.840.1.113883.6.84


A Moment to Discuss OIDs

» Hierarchical system› 0: itu-t› 1: iso

• 2: member body› 2: joint-iso-itu-t

• 16: countryo ISO 3166 country code (e.g. Canada = 124)

2.16.124.113635


It gets more complicated

» Surely no one in this room believes that thereare only 184 languages in the world» ISO 639-2 uses a 3-character language codeand has more than 450 entries» ISO 639-3 also uses a 3-character languagecode and has about 7700 entries» Example:

› Arabic• Chadian Arabic• Libyan Arabic (and others)


How Important is this?

» Truthfully, I’m not sure» In Canada, it might be “good enough” to record“Arabic”, rather than “Libyan Arabic”

› But if I were implementing an e-Health system inthe middle-east, I might have a different opinion» The important part is that the HL7 standardrecognizes that some implementations need tomake different choices


What Does this Example Reveal about the Design of HL7v3?


Key Idea

» We can talk about the notion that people have communication preferences in a particular “HumanLanguage” without needing to be specific about what codes are being used

› More to the point, HL7 does define many types this way


How is this used in HL7 Types?


XML Representation

» Here’s a portion of an HL7 message

<person classCode="PSN" determinerCode="INSTANCE" >...<administrativeGenderCode code="en"codeSystem="1.0.639.1"/><languageCommunication><languageCode code="en" codeSystem="1.0.639.1"/></languageCommunication>...</person>

» Why is this wrong?


Using Concept Domains in Definitions

A portion of the message definition for PRPA_MT010001CA


Defining an HL7 Environment

» For any code attribute someone must define:› What Concept Domain is applicable› What Code System is bound to that Concept Domain

» In today’s world, to the best of my knowledge, there is no single source of all those definitions

› To the extent that much of it is defined, much of it is defined in word documents or spreadsheets


Quick Recap

» HL7 uses codes a lot» Codes have two parts:

› code› code system (OID)

» A “Concept Domain” defines an abstract notion where a code can be used» A “Code System” is a collection of codes defined together and managed by some group

› Formal identification via an OID (e.g. 1.0.639.1)› Informal identification via name (e.g. ISO 639-1)


Agenda



Let’s Look at a Transport Wrapper


Let’s Look at a Transport Wrapper

A portion of a sample Find Candidates message


It’s Like I Totally Lied

» Where are the Code System OIDs?


Ah, But these are “Simple” Codes


Code Data Types

» CS: Coded Simple Value» CV: Coded Value» CE: Coded with Equivalents» CD: Concept Descriptor

» also:

» SC: Character String with Code» CD.LAB: Concept Descriptor (LAB)


Code Data Types

» HL7 also defines:› CO: Coded Ordinal

» I haven’t seen this example occur in nature


Where are the Data Types defined?

» You have to consult two sources:› The HL7 site

• http://www.hl7.org/v3ballot/html/infrastructure/ datatypes/datatypes.html

› The Data Types document of the pan-Canadian standards releases

» The HL7 site references the international standard; Canada has customized the standard


Example of Customization

» The International Standard for a basic CodedValue type allows something that looks like this:

<administrativeGenderCodecode="F"codeSystem="2.16.840.1.113883.5.1"displayName="Female"codeSystemName="HL7v3 AdministrativeGender" />

» The “displayName” and “codeSystemName”properties are Not Permitted according to theCanadian Data Types standard


Coded Simple Value (CS)

» The Code System is implicit» This type is only used in some very limited circumstances

› HL7 defines and manages the list of valid codes› Usually related to

• message structure; or• transport wrapper data.


Coded Simple in Transport Wrapper

A portion of a sample Find Candidates message


Coded Simple Value

» The Code System is implicit» This type is only used in some very limitedcircumstances

› HL7 defines and manages the list of valid codes› Usually related to

• message structure;• transport wrapper data; or• part of another data type.

<quantity value="400" unit="ml" />


XML Representation

» When a CS value is “immutable” (old term:“structural”) then the code value appears as anXML attribute

<sender typeCode="SND" > ...

» Otherwise a CS value appears as a normal XMLelement

<processingCode code="P" />

» I think it’s largely because of the first case thatthey don’t show the codeSystem


Coded Value (CV)

» Possibly the most basic Code type

<administrativeGenderCode code="F" codeSystem="2.16.840.1.113883.5.1" />


Coded with Equivalents (CE)

» Introduces the concept of “equivalent” codes» Consider the example of HumanLanguage

<code code="eng" codeSystem="1.0.639.2"><translation code="en" codeSystem="1.0.639.1"/>

</code>

» This is a bad example, because language code is never defined as a “CE” type.

› Language is a pretty simple concept


Coded with Equivalents (CE)

» Consider the example of Clinical Drug› In Canada, most pharmacists tend to refer to drugs using DIN numbers› Other drug numbers exist. E.g.: Health Canada defines an Active Ingredient Group code› There are times when they’re equivalent ways of referring to the same thing

<code code="02147629" codeSystem="2.16.840.1.113883.5.1105"> <translation code="0131282002"

codeSystem="2.16.840.1.113883.5.1106"/>

</code>

» Both indicate 400mg of Acebutol


Concept Descriptor (CD)

» Very similar to CE» There’s a key difference between HL7 International and HL7 Canada, here

› qualifiers» Canada has changed its support for qualifiers

› V02R02 (MR 2007) vs. R02.04.02 (MR 2009)» Notion of post-coordinated codes

› HL7 International would use a series of qualifiers to provide qualifying codes


Post-Coordinated Values

» Used to combine codes more expressively

<valuecode="397956004:363704007=24136001:272741003=7771000{363699004=304120007,260686004= 257867005}" codeSystem="2.16.840.1.113883.6.96"/>

› 397956004 = prosthetic arthroplasty of the hip› 363704007 = Procedure site› 24136001 = Hip joint structure› 272741003 = laterality› 7771000 = left› 363699004 = direct device› 304120007 = Total hip replacement prosthesis


Post-Coordinated Values using Qualifiers


Character String with Code (SC)

» Key idea: the string is more salient than the code is» Only example I know of is address parts:


Concept Descriptor for Lab (CD.LAB)

» Same as CD, but displayName is permitted


Object Hierarchy

This is a strange,backward hierarchy


Additional Considerations

» Original Text» Coding Strength

› CNE (coded, non-extensible)› CWE (coded, with extensibility)


Recap

» What we’ve learned about Data Types› CS, CV, CD, CE, SC

» Translations» Qualifiers» Original Text and Coding Strength


Exercise

» Find Candidates Payload› Peruse the MIF› Look for all the properties (attributes) that are defined as code values

• Hint: look at <mif:type name=”??” />› What kind of codes are they?› Also, look at the XSDs and see how the corresponding properties (XML Elements) are defined there


Agenda



Code System and Concept Domains

» We’ve touched on Code Systems and ConceptDomains before

› All codes associated with a particular “standard” are part of the same code system› A Concept Domain is used to describe a particular business concept that can be described using a code.


Sample Concept Domains


Major Concept Domains

» ActCode» EntityCode» ObservationValue


Hierarchical Concept Domains


What is a Value Set?

» You could think of it as a subset of a code system

› A value set includes some or all of the codes from a code system

› All codes in a value set come from the same code system


An Example

» Code System: Confidentiality» Codes (about 14 in total)

› N: Normal› R: Restricted› HIV: HIV-related› ETH: Substance-abuse related› PSY: Psychiatry-related› C: Celebrity› T: Taboo


x_VeryBasicConfidentialityKind

» Only 2 codes› N: Normal› R: Restricted

» Note that there are relationships between codes› Everything except “N” can been “rolled up” to “R”


Other Thoughts

» SNOMED CT› one code system that tries to describe medical terminology across many, many concept domains› We generally care about specific subsets (Value Sets), rather than the whole code system

• e.g.: ActServiceDeliveryLocationService» Inconveniently, HL7.org often uses the same names to describe a Value Set and a Concept Domain

› Adds to confusion


Binding


Agenda



Common Healthcare Standards

» DIN› A Drug Identification Number (DIN) is a computer-generated eight digit number assigned by Health Canada to a drug product prior to being marketed in Canada. It uniquely identifies all drug products sold in a dosage form in Canada and is located on the label of prescription and over-the-counter drug products that have been evaluated and authorized for sale in Canada.



» SNOMED CT› SNOMED CT (Systematized Nomenclature of Medicine -- Clinical Terms), is a systematically organised computer processable collection of medical terminology covering most areas of clinical information such as diseases, findings, procedures, microorganisms, substances, etc.



» LOINC› Logical Observation Identifiers Names and Codes (LOINC) is a database and universal standard for identifying medical laboratory observations. It was developed and is maintained by the Regenstrief Institute, a US non-profit medical research organization, in 1994.



» ICD-10› The International Statistical Classification of Diseases and Related Health Problems, 10th Revision (known as "ICD-10") is a medical classification list for the coding of diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases, as maintained by the World Health Organization (WHO).


Implementation Considerations

» Change and Lifecycles» Just because a standard exists, doesn’t mean that it never changes

› Country codes• Example: Sint Maarten


More on Lifecycle

» Some code values are bound to different pan- Canadian standards releases.» A jurisdiction that implements a prior release should use the previous codes» On the other hand, some code systems are updated regularly

› e.g.: ClinicalDrug• The list of drug products managed by Health Canada is updated every quarter

» There’s no formal distinction of these code categories


Mapping

» At Partnership, it’s not uncommon to hear jurisdictions talk about “implementation”

› What they’re often talking about is code mapping» In the target architecture, Accenture plans to use a HLI to provide mapping services

› Don’t assume that mapping is a trivial exercise› Some concepts don’t map neatly


Final Recap

» Concepts» Code Data Types» Concept Domains, CodeSystems and Value Sets» Implementation Concerns

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canadian healthcare codes and terminology standards

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