LOINC AND SNOMED

Tim Benson

Abies Ltd

Wellcome Trust Sintero Server Project

Cardiff University

Author:

Principles of Health Interoperability HL7 and SNOMED, Springer 2010

OUTLINE

Origins of LOINC Origins of SNOMED CT Complementary or Competitive

SCOPE OF LOINC

Clinical Laboratory Tests The test not the result

Clinical observables “Eye colour”, not “Blue eyes”

Form headings Document types Assessment scales

ORIGINS OF LOINC

Logical Observation Identifiers Names and Codes

Designed for use in interoperability Clem McDonald

ASTM 1238:88 Standard Specification for Transferring Clinical Laboratory Data Between Independent Computer Systems

HL7 V2.0 1988 OBX Segment

EU EUCLIDES and OpenLabs projects

HL7 V2 OBX SEGMENT

Turn-round document Observable

Code Value

Code Physical quantity

EUCLIDES

European Clinical Laboratory Data Exchange Standard 1988-1991 Georges De Moor, Gent

6 dimensional classification

LOINC CODES

LOINC Code Consecutive number + Check digit e.g. 12345-9

Short convenient name Long common name All codes are pre-coordinated to common

concept model Six dimensions

slightly different from EUCLIDES

LOINC DIMENSIONS

Component what is being measured

Property kind of property measured

Timing point in time or period

System sample or body part

Scale nominal, ordinal, interval or ratio

Method procedure used to produce the result or other

observation

RELMA

Regenstrief LOINC Mapping Assistant LOINC database search Map local codes to LOINC codes

PROBLEMS OF LOINC

Complex Many similar codes with only small

differences mass concentration v molecular concentration anatomical position of pulse or BP

Dimensions are not hierarchical so limits subsumption testing

GOOD ASPECTS OF LOINC

Completely free Does what it claims to do (but no more) Fit for purpose Easy and quick to add new codes

ORIGINS OF SNOMED CT (1)

SNOMED CAP committee 1955 SNOP 1965

topography morphology etiology function (physiology)

SNOMED 1975 SNOMED III 1993 SNOMED RT (Reference Terminology) 1997

ORIGINS OF SNOMED CT (2)

Read Codes Coded terms in EHR

e.g. “Blue Eyes” Developed by Abies and James Read for use in

GP computer system 1983-1986 Purchased by DH in 1990

V2 1990 Version 3 (CTV3) 1996

Used by all GPs in UK (100%) Basis of payment Unsuccessful in other specialties

READ CODE (V1,2) CHAPTERS

Diagnoses ICD Chapters A-Z

Medication BNF Chapters a-z

History and physical Occupations (0), history and symptoms (1),

physical examination findings (2) Procedures

Diagnostic (3), lab (4), imaging (5), prevention (6), therapy (7), surgery (8), admin (9)

SNOMED CT

Merger of Read Codes and SNOMED RT Reference Terminology

All concepts are in hierarchies (19) Concepts Descriptions (terms) Relationships

Defining, qualifying, sub-type, association Description Logic

PROBLEMS OF SNOMED CT

Much legacy baggage Lack of transparency

Lack of free access Lack of good web-based tools

Complexity Post-coordination is not yet a practical

proposition Undefined boundaries

Over-sold as answer to all terminology problems

BENEFITS OF SNOMED CT

Future-proof structure Inherently multi-lingual Broad coverage

EDUCATION PROBLEM

Few people are competent in both LOINC and SNOMED

Clinical terminology is not taught well One of 186 topics in AMIA Core Curriculum for

Clinical Informatics (JAMIA, 2009) Formal training is essential

93% of all those who rated themselves as competent had had more than 3 days formal training in SNOMED CT (Report for DH, unpublished)

EDUCATION – NEEDS A BLENDED APPROACH

1. Learn by doing (assignments and examples)

2. Face-to-face presentations3. Web-based presentations and videos4. User guides and books5. Pick it up from colleagues

LOINC AND SNOMED CT TOGETHER

Clinical statement consists of: Narrative text Context (who, when , where, etc) Observable Finding

(Rector A. What’s in a code, MEDINFO 2007)

OBSERVABLE

“Observables” are qualities of patients that are present in all patients and whose values or states are determined by

observation This is what LOINC is designed to code and

does it well

FINDING

Information specific to a particular patient Finding = Observable + Value Value may be various data types

Physical quantity, code, date, text etc SNOMED CT is good for Observation Value

Codes

CONCLUSIONS

LOINC and SNOMED CT were originally designed to do different things

They are complementary