Dave Nurse

John Chelsom

1. Overview
2. System architecture
   1. Browser-based interface
   2. XML delivery middleware
      1. Java application server
      2. Case notes kernel
      3. Access control framework
   3. XML database and database access layer
   4. Interfaces to HIS, workflow and departmental systems
3. Benefits of the XML approach

Overview

Several secondary care providers in the UK (Hospital Trusts) have succeeded in extending the functionality of their HIS 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, the GP 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.

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.

Previous

Table of Contents

System architecture

The overall architecture of the Case Notes system is shown in the figure. The main components are:

Figure 1 . 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:

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:

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:

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:

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 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 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 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:

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:

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.

Previous

Table of Contents

Benefits of the XML approach

XML is used in several roles within the Case Notes architecture:

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.

Previous

Table of Contents