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Analytics with SNOMED CT may be deployed on a wide range of data sources as summarized in the table below. These data sources are also known as the 'substrate' of the analytics. Please note that data which is not natively coded using SNOMED CT may be transformed using one of the techniques described in section  5 Preparing Data for Analytics. These techniques may be used to transform heterogeneous data recorded using free text or a variety of code systems into SNOMED CT, which can serve as a common reference terminology for analysis.

Table 3.3-1: Direct and indirect substrates for SNOMED CT based analytics

Analytics Substrate



Information Model

Unstructured free text document


Dictated clinical letter

Natural language


None or informal headings


Typed discharge summary letter

Structured documents with free text fields


Assessment form

Natural language


Standardized headings and fields


Discharge summary form

Structured documents with free text and post-coded classification (i.e. added by clinical coders after the clinical event

Discharge summary form with post-coded classification

Classifications (e.g. ICD)

Formal information model (typically simple)

Structured documents with non-SNOMED CT coding (e.g. proprietary, local or other coding system)



Standalone clinical application using departmental codes

Local code system, controlled vocabulary or legacy clinical terminology



Formal information model



Enterprise-wide healthcare system using local dictionaries and pick-lists

Electronic patient record using regional coding system (such as UK Primary Care systems)

Structured documents with SNOMED CT content


Cardiology report



Formal information model


GP event summary

'Big data' data store


Data warehouse

Various coding systems


Mixture of both structured and unstructured data


Data store containing a mixture of substrates