Diagnoses, damned diagnoses and statistics: Dealing with disparate diagnostic coding systems within the New South Wales Emergency Department Data Collection.

OBJECTIVES

The aims of the present study were to describe the distribution of Systematised Nomenclature of Medicine - Clinical Terms (SNOMED-CT) codes used in the current New South Wales Emergency Department Data Collection (NSW EDDC) and classify duplicate and redundant terms into clinically meaningful sub-groups for future analyses.

METHODS

This was an analysis of ED diagnosis codes using a large state-wide administrative ED dataset between 2015 and 2018.

RESULTS

A total of 7.4 million (77%) of ED episode diagnoses were coded with SNOMED-CT. Of those coded with SNOMED-CT, 12 152 unique codes were identified. Around 1000 of the most frequently used codes accounted for 90% of the presentations coded with SNOMED-CT and 5000 codes accounted for 99.8% of these. Around 7000 codes were deemed to be redundant, and duplication in terms exists across all sub-groups.

CONCLUSION

The use of SNOMED-CT in the NSW EDDC has resulted in substantial use of non-specific, duplicate and redundant codes, limiting the capacity of the NSW EDDC to be used for effective data analysis.