Standardized and normalized data reference models are
needed to represent clinical information. One of the benefits
of clinical data models is that they support the level of complexity
required to correctly interpret the information with
context. The data models also facilitate the processing of
semantic meaning within the data, which is of growing interest
in EHR development. To achieve normalized clinical data
models, a strategy known as the two-level methodology is proposed
to decouple knowledge models from system design
The methodology provides fiexibility for the integration of different
knowledge models with the clinical systems while the
integration can be independent from the system design. This
strategy is being adopted by an increasing number of systems.
Examples of normalized reference models to represent the
clinical information includes EN-ISO13606, OpenEHR, and HL7
RIM-CDA