Relationship of Classifications and Terminologies

Purposes of Classifications and Terminologies

Classifications and terminologies are designed for distinctly different purposes and satisfy diverse user data requirements. They should be considered complementary, as neither a clinical terminology nor a classification can, by itself, serve all of the purposes for which health information is currently used or will be used in the future. Classifications are a necessary adjunct to terminologies for standardized summarization for statistical and external reporting purposes.

Classification systems such as ICD-9-CM, ICD-10-CM, and ICD-10-PCS are considered “output” systems and are not intended or designed for the primary documentation of clinical care. They are typically used for external reporting requirements or other uses where grouping data is advantageous. They can be used in either paper-based or EHR systems. A classification system arranges or organizes like or related entities for easy retrieval. It aggregates granular clinical concepts into manageable categories for secondary data purposes. The uses being made today of data derived from classification systems go well beyond the purposes for which these data were used in the 1970s when ICD-9-CM was designed and implemented.
The purposes for which this data are used today include:

Measuring the quality, safety (or medical errors), and efficacy of care
Making clinical decisions based on output from multiple systems
Enabling the connectivity of information systems for continuity of care
Designing payment systems and processing claims for reimbursement
Conducting research, epidemiological studies, and clinical trials
Setting health policy
Designing healthcare delivery systems
Monitoring resource utilization
Improving clinical, financial, and administrative performance
Identifying fraudulent or abusive practices
Managing care and disease processes
Tracking public health and risks
Providing data to consumers regarding costs and outcomes of treatment options

Clinical terminologies such as SNOMED-CT® are “input” systems and are designed for the primary documentation of clinical care. Since they codify the clinical information captured during the course of patient care, terminologies can only be used in electronic health record (EHR) systems.

Mapping Between Terminologies and Classifications

Together, standard clinical terminologies and classifications represent a common medical language that allows data to be shared between EHR systems. Therefore, standard, modern clinical terminologies and classifications must be incorporated into EHR systems in order to achieve system interoperability and the benefits of a national health information infrastructure.

The expanded availability of SNOMED-CT® made possible by the federal government licensing agreement increases the urgency of replacing ICD-9-CM with ICD-10-CM/PCS so the development of mapping tools to the ICD-10-CM and ICD-10-PCS can be initiated. Mapping is the process of linking content from one terminology to another or to a classification.

The use of a map from SNOMED-CT to ICD-10-CM and ICD-10-PCS will allow clinical information captured at a very granular level to be grouped for reporting and statistical analysis purposes. Mapping a terminology to modern classification systems:

Decreases administrative costs
Decreases time in revenue cycle
Increases data specificity and accuracy
Maintains comparable data

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