Understanding snomed ct

Understanding the basis of SNOMED CT

Dr SB Bhattacharyya

MBBS, MBA, FCGP

Member, National EHR Standardisation Committee, MoH&FW, GoI

Member, IMA Standing Committee for IT, IMA Headquarters

Member, Health Informatics Sectional Committee, MHD 17, BIS

President (2010 – 2011), IAMI

Convergence of Medical Science with Computer & Information Science – making electronic clinical documents “smart”

SNOMED CT – Systematised Nomenclature Of Medicine – Clinical Terminology

Dr SB Bhattacharyya© 2

If you have trouble figuring out what SNOMED CT, give yourself a break. It is not easy and requires in-depth understanding of the medical domain, and basic understanding of some aspects computer, information and linguistic sciences


What is recorded in clinical documents?

• The entries in a record represent the thoughts of the author had when about the item

• So, when a doctor records “cough with fever” in chief complaint or “family history of COPD” in family history or “O/E chest clear” in physical exam or “influenza” in diagnosis, the entries reflect the thought the doctor had about chief compliant or family history or physical exam or diagnosis


How SNOMED CT makes “sense” of what has been recorded in clinical documents?

• A lexicographer provides the meanings of terms (semasiology)

• A terminologist provides the definitions of concepts using various terms (onomasiology)

• These definitions are actually the knowledge representation or ontology (information science)

• Using Description Logics (computer science) these ontologies can be coded for machine-processing

• Thus machines can be enabled to “understand” concepts



• By matching various synonymous terms to concepts, the same codes can be made human-readable

• Thus, a human-machine bridge can be created to record and interpret records



• SNOMED CT provides both the machine-processable and human-readable codes

• Using it, clinical documents can be coded, making them unambiguously “understandable” by both machines and humans alike

• Currently, no other clinical code system exists that can accomplish this



• SNOMED CT Expressions are its codes

• These are of two types• Pre-coordinated

• Post-coordinated

• Pre-coordinated expressions are simple constructs and usually represent a post-coordinated expression

• Post-coordinated expressions are complex constructs composed according to the concept model



• The concept model is basically the Description Logic and reflects the ontology, i.e. knowledge representation, of clinical concepts

• The terms are human-readable “codes” while the concept identifier’s are the machine-processable codes


How SNOMED CT makes “sense” of what has been recorded in clinical documents?• Every concept in SNOMED CT has a definition

• Every concept uses other concepts to help define it, except the root concept that uses itself

• This definition is available as expressions• To machines as machine-processable expressions

• To humans as human-readable expressions

• Users can also record their own special concepts by making good use of this process to define them • For concepts already defined – pre-coordinated expressions

• For concepts not currently defined – post-coordinated expressions



• Since every data in a clinical document is coded in a machine-processable and human-readable format (if the latter is missing, it can be easily generated and presented), the machines can process the code and “figure out” what it is by reversing the logic of creation of expression

• Usual logic: human concepts create ontology use DL expressions

• Reverse logic: expressions use DL “derive” ontology human concepts


Why use SNOMED CT (instead of, for example, ICD or LOINC)?

• Querying records can now be made as granular as possible and in a myriad of ways

• Resultant data sets can reveal very rich information from which knowledge can be gained and wisdom derived to help deliver ever-better health care

• Every clinically-relevant part of clinical documents can be coded, the data from the entire record can be extracted and used for further action


How SNOMED CT helps in data analytics?

• Since ~70% of analytics involves data preparation for analysis, the ready-availability of clinical data in machine-processable coded format makes automated analysis that much closer to reality

• This helps make it possible for making clinically-relevant (right) information available at the (right) point of care (right) just-in-time



Thanks!

Healthcare

Understanding snomed ct