This is an extract from a presentation which i gave recently where i have been asked to present the different EHR architecturial patterns and the advantages and challenges associated with each of the patterns
There are three types of EHR Models/Patterns which are in wide use
Ø Central Repository Model
Ø Federated Model
Ø Hybrid Model
Ø Health record is stored at point of care systems as well as a common repository
Ø Patients record is identified by a unique identifier which may be allocated by the central repository or a national organization
Ø Local record may be a detailed record and the shared record a summary record
Ø Thin EHR
Ø Easy and Quicker access to the data
Ø Security controls easy to implement compared to federated model
Ø Better price/performance ratio
Ø Data can be entered into the local systems or directly
Ø Allows data to be cleansed and its terminology standardized by reference to a canonical controlled vocabulary
Ø Consistent interpretation of data by different clinical settings
Ø Determining ownership of data between organizations
Ø Infrastructure and scalability issues
Ø Decoupling and Business continuity issues
Ø Resolving conflicting data issues between central and local e.g. allergies information
Ø Governance and funding issues between different organizations
Ø Health record is stored at their places of origin- point of care systems
Ø Patients unified record is fetched from different systems using patient indexes and record locator services
Ø The fetched record will usually be a agreed subset of data in the point-of-care systems
Ø Thick EHR
Ø Avoids the infrastructure and ownership issues that are barriers to information sharing.
Ø Decentralized data approach safeguards privacy and security by affording a pathway that facilitates information exchange while leaving appropriate controls in place.
Ø Infrastructure can be relatively small and requires less capital and ongoing operating expense.
Ø Data can be managed locally
e.g. deletions without considering the impact on data sharing.
Ø Appealing in theory but has many implementation and performance difficulties in practice, particularly for large systems with many records and many different federated EHR sources (or EHR nodes).
Ø Rely on a number of factors such as efficient distributed queries, short latencies, and compatible security models and are only as good as the weakest link in the chain.
Ø Combination of the two architecture types
Ø Patients record are identified by a combination of identifiers – national and local
Ø Central record has only demographics and limited clinical data with access control and record locators for detailed data
Ø Thin and Thick EHR
Ø Provides all of the advantages of a centralized data architecture for the most relevant clinical data required for care.
Ø Provides benefits of the federated architecture with access to detailed record
Ø Local systems still retain control of their data with access to relevant patient
data from other organizations
Ø Deciding the scope of shared data and unshared data
Ø Different access controls required locally and centrally for similar data of a patient.