SynExML as a vehicle for Electronic Patient Records   Table of contents   Indexes   Impact of an XML repository in development of XML messages
Electronic Case Notes
Electronic Health Record
 Intranet  
Multi-tiered architecture
 WWW  
 XML 
 

XML data warehousing for browser-based Electronic Health Records

Nurse, Dave
 
 Dave  Nurse
 Head of Research
  CSW Informatics Ltd 
 Oxford 
 United Kingdom 
CSW Informatics Ltd,  4220 Nash Court
Oxford Business Park South
Oxford   OX4 2RU United Kingdom email: dave.nurse@csw.co.uk web site: www.csw.co.uk
 Biography
 Dave Nurse — Dave holds a Fellowship in Clinical Biochemistry from Portsmouth Polytechnic and an MSc in Medical Informatics from the University of Wales College of Medicine. His thesis was on the application of Hypertext systems for clinical support information. Dave is a specialist in clinical laboratory computing and has gained wide experience across all areas of medical informatics. His role as Head of Research at CSW involves the investigation and application of new technologies for CSW's solutions in the Healthcare, Engineering, Financial and Publishing sectors.
 Dave is a frequent speaker at informatics events and conferences, and has published many papers on medical informatics topics in journals that include the Journal of the Institute of Electronics Engineers and Healthcare Computing.
 Chelsom, John 
 
 John  Chelsom
 Managing Director
  CSW Informatics Ltd 
 Oxford 
 United Kingdom 
CSW Informatics Ltd,  4220 Nash Court
Oxford Business Park South
Oxford   OX4 2RU United Kingdom email: john.chelsom@csw.co.uk web site: www.csw.co.uk
 Biography
 Dr John Chelsom — Dr John Chelsom is Managing Director of CSW Informatics, a company dedicated to providing object-level information management solutions using XML, SGML and database technology. Originally trained as an electrical engineer, John worked first as an X-Ray engineer and later gained a PhD for work on the application of knowledge based systems in medicine. Since founding CSW Informatics he has been responsible for the design and development of XML and SGML information management systems for some of the world's most prestigious engineering, healthcare and publishing organisations.
 John is a regular speaker at XML and SGML conferences, was a contributing author for the SGML Buyer's Guide and is the presenter of the Technology Appraisals seminar series on XML Databases.
 Abstract
 Electronic health record summaries are now being deployed in the UK, using XML to represent, store and display information that is extracted from existing hospital systems. The Electronic Case Notes Folder is an XML data warehouse designed to provide a clinician-centred view of the patient's history, with a web browser as the user interface.
 

Overview

 HIS, Hospital Information System  
 		Several secondary care providers in the UK (Hospital Trusts) have succeeded in extending the functionality of theirHIS by integrating data derived from hospital-based departmental systems. They have further extended this to include communications to primary care providers (General Pracitioners). Using workflow systems, theGP referral letter can also be captured using a combination of scanning and GP email. Subsequent consultant to GP clinic letters can also be produced through the same workflow systems and logically linked to the original referral letter.
GP, General Pracitioner
 		The objective of the Electronic Case Notes Folder described in this paper is to combine extracts of information from the HIS, from departmental systems and from workflow systems and warehouse them in a way that can be navigated easily using a Web browser.
 The Case Notes Folder is designed as a clinical tool to be used by clinicians and staff who directly support the clinician in patient care. The composition of the folder and the views it generates were prototyped and simulated for demonstration and feedback in a number of UK Hospital Trusts. The conceptual approach chosen reflects the hierarchical structure of the traditional paper-based casenote folder. Different views of the folder are possible depending on the access level and preference of the user. Feedback from the prototype system has been incorporated into the first generation Case Notes now being deployed in live systems.
 Patient records are created and maintained as XML documents within an XML database. Data feeds from the HIS make use of existing HIS interfaces with some customisation to meet the data requirements of the XML patient record database. HIS extracts are triggered by events occurring within the system. As updates take place, the XML database can provide full auditing of transactions that have taken place. Access to the Case Note folder browser application is controlled by a security layer that can be integrated with the HIS system. The Web server provides the middle layer between the user interacting with the browser and the XML database that serves the Case Note folders.
 

System architecture

 The overall architecture of the Case Notes system is shown in the figure. The main components are:
 
  • Browser-based interface
    •  
  • XML delivery middleware
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  • Database access layer
    •  
  • XML database
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  • Interfaces to HIS, workflow and departmental systems
    •  
    Overview of case notes architecture
     

    Browser-based interface

     The browser-based interface, using pure HTML on the desktop, is key to the widespread deployment and acceptance of patient record systems. The provision of IT services in the UK Health Service (the NHS) is characterised by de-centralised implementation strategies and limited budgets. If a distributed system such as Case Notes is to be accepted readily it must overcome the barriers that such an environment imposes:
     
  • a wide variety of client hardware, operating systems and browsers
    •  
  • 2nd, 3rd and 4th generation browsers with no impetus to upgrade
    •  
  • low specification client machines
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  • low bandwidth Internet connections
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  • little or no budget for training
    •  
  • limited access to IT support services
    •  Using a browser-based interface, with pure HTML delivered to the desktop, addresses all these barriers to adoption. Browser technology can be deployed quickly with little or no training or requirement for support from an IT department. By transforming XML to HTML in the middle layers of the application, a wide range of browsers and operating environments can be supported.
     

    XML delivery middleware

     The XML delivery middleware consists of three main sub-components:
     
  • a Java Application Server
    •  
  • the Case Notes Kernel
    •  
  • an Access Control Framework
    •  

    Java application server

     The Java Application Server uses Java Server Pages (JSP) and Java servlets to implement the essential functions of a scaleable XML application server, including:
     
  • session management
    •  
  • process management (of a pool of database connections)
    •  
  • XML processing (including transformation and profiling)
    •  The Java Application Server is implemented entirely in Java, which makes it portable across operating systems and also opens the possibility of distributing some components to run as applets in the desktop browser in future implementations.
     Session initiation is achieved by authenticating the user name and password against the database of users (see the Access Control Framework). The Java Application Server then maintains the state of the session on behalf of the client and manages:
     
  • session audit
    •  
  • session time-out
    •  
  • session close
    •  

    Case notes kernel

     The Case Notes Kernel provides the core features of the Case Notes system, implemented as Java servlets and applications which run under the control of the Java Application Server. The features provided by the kernel include:
     
  • the basic episode/event model of case notes
    •  
  • demographics module
    •  
  • framework for plug-in modules
    •  
  • configurable user interface
    •  The basic episode/event model and demographics module provide the minimum configuration of Case Notes. Other modules, such as laboratory test requests/reporting, GP and consultant letters, Xray interpretation, and discharge summaries, are available as plug-in modules. The configuration of the interface and the plug-in modules is achieved through XML configuration files that describe the active modules and the layout of the interface.
     

    Access control framework

     The Access Control Framework has been designed to support the Caldicott principles of data security; it comprises the following modules:
     
  • User management
    •  
  • Access control management
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  • Applications management
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  • Patient list management
    •  User characteristics are uniquely identified by a user id and settings are stored encrypted within an XML access control document. Login takes place through a username, password Web browser form submission. The interface can be customised to integrate with any existing intranet style guidelines. The Access Control process supports:
     
  • The use of passwords of an appropriate length which are changed regularly
    •  
  • GPs will be registered individually with no use of collective passwords
    •  
  • The address of the device being used to access the system will need to be registered
    •  The Access Control Framework is linked with an intranet applications directory, stored persistently in a relational database. This allows access to other intranet applications through the Case Notes interface, under the control of the Access Control Framework. Application management is carried out through a browser-based module that allows an administrator to perform maintenance procedures, including:
     
  • List applications
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  • Search for an application
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  • View application characteristics
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  • Amend application characteristics
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  • Add a new application
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  • Delete an application
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  • Add, amend and delete user or group access
    •  The patient list is maintained in the back-end database. At logon the patient list is available to the clinician for immediate patient selection. Using the patient id or NHS number the list management module includes the ability to:
     
  • Add new entries to the list
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  • Amend entries on the list
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  • Delete entries from the list
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  • Share the list with other members of the same clinical team
    •  Third party intranet applications are able to access the session management and applications databases using ODBC or JDBC.
     

    XML database and database access layer

     The Case Notes system has been tested using both relational and object-oriented databases for the XML repository. All database access in the Java middleware and plug-in modules is abstracted to a single database access class, that can be re-implemented for different databases.
     Because each patient record can be treated as a distinct entity, without any relationships to other records in the system, the XML repository can be split into discrete databases, using different DBMS servers and physical servers if necessary. Within the database access layer, an initial look-up on the patient id is sufficient to locate the correct database for the patient. This mechanism makes the XML repository highly scaleable, in line with the other modules of the system.
     To date, the only limitation on the number of records that can be handled by the system is imposed by the 'database bloat' encountered when using object databases for the XML repository. Typically, the object-oriented databases exhibit an expansion of between 10 and 100 when taking an XML document from the file system to the database. Although this isn't necessarily a problem in itself, it does have significant impact on the amount of disk space required to manage hundreds of thousands of patient records.
     

    Interfaces to HIS, workflow and departmental systems

     Interfaces to the Hospital Information System (HIS), workflow or departmental systems can be made through bespoke integration with third party integration engines (such as Datagate) or directly to the systems themselves. A set of tools is provided to assist with the direct integration through SGML or XML files.
     A Case Notes module called the HIS Output Monitor can be set up to poll one or more network locations for input files, that can be SGML or XML. These files are parsed and, if recognised to be valid input for the Case Notes XML repository are imported to the correct patient record. Configuration is required to create DTDs and/or filters to handle the output of the HIS and other systems. By using the minimisation features of SGML it is generally possible to process reports taken from the HIS, without modification, and interpret them as SGML documents. From there, they can be converted to XML before import to the Case Notes repository.
     

    Benefits of the XML approach

     XML is used in several roles within the Case Notes architecture:
     
  • as the integration data format (with SGML) for legacy systems
    •  
  • for messaging through TCP/IP sockets in the application server
    •  
  • for profiling and transformation to pure HTML in the client browsers
    •  
  • as the base data model (XML DTDs and schema) for the patient record repository
    •  
  • for configuration of the application server and plug-in modules
    •  The main benefit in using XML is in creating an open and portable environment, from which information can easily be exchanged with other systems. As yet, there are no univerally accepted standards for the storage and exchange of health records; the use of XML throughout the Case Notes architecture ensures that any future standards can be incorporated easily, either within Case Notes itself or through transformation for information exchange.
    SynExML as a vehicle for Electronic Patient Records   Table of contents   Indexes   Impact of an XML repository in development of XML messages