*********************** TITLE PAGE *********************** Accepted for publication, Computers in Human Behavior, Elsevier, 2007

Transcription

1 *********************** TITLE PAGE *********************** Accepted for publication, Computers in Human Behavior, Elsevier, 2007 A semantic web-based system for information support to emergency healthcare delivery M. Botsivaly 1, F. Malamateniou 2, G. Vassilacopoulos 1 and A. Macris 3 1 Department of Informatics, University of Piraeus, Greece 2 Informatics and Telematics Institute, Greece 3 Department of Business Administration, University of Piraeus, Greece Author to whom correspondence should be directed: Prof. George Vassilacopoulos Department of Informatics University of Piraeus 80, Karaoli & Dimitriou str. Piraeus GREECE Tel: Fax: gvass@unipi.gr *********************************************************** - 1 -

2 A semantic web-based system for information support to emergency healthcare delivery Abstract Emergency healthcare delivery involves a variety of interrelated activities performed by a number of disparate healthcare providers, such as the referring physician, the ambulance service and the emergency department of a hospital. As patient information is scattered around the participating healthcare providers, there is a need for a system architecture that enables representation of patient information in a structurally and semantically compatible form, thus facilitating the retrieval of integrated patient information on demand and the exchange of related patient information among heterogeneous information systems. An appealing approach towards this direction appears to be the Semantic Web which constitutes an environment where both human and machine agents will be able to communicate on a semantics basis. This paper presents a semantic web-based system which aims at facilitating access to integrated emergency medical information by authorized users within the boundaries of a health district. The structure and semantics of medical information related with emergency medical episodes are expressed with an appropriately designed ontology, which is based upon the HL7-CDA standard and which is used in the creation of a semantically annotated web service that provides readily access to emergency medical information retrieval and exchange among geographically disperse and diverge information systems. Keywords Emergency Care, Semantic Web, CDA, Ontology - 2 -

3 1. Introduction Emergency medical care is an increasingly collaborative enterprise involving a wide range of medical, paramedical and administrative activities that are performed from the time of a call for an ambulance to the time of patient s discharge from the emergency department (ED) of a hospital. Thus, an emergency medical system (EMS) is part of the healthcare system and can be seen as a virtual healthcare enterprise comprising geographically dispersed and organizationally disparate healthcare providers (e.g., health centers, general practitioners, ambulance services and hospital EDs) that collaborate towards delivering shared and integrated care to patients (Poulymenopoulou and Vassilacopoulos, 2006). Besides, an EMS interacts with the general hospital care system, as patients may need service by physicians and nurses which are specialized to particular injuries (e.g., orthopedics) or specialized by level of urgency, may undergo tests (e.g., X-ray, CT Scan and MRI) that are performed through the hospital s radiology department, may be moved to an operating room for surgery and may be admitted to the hospital once emergency treatment is completed. The drive in healthcare towards shared, integrated and continuity of care has created a growing need for collaboration across settings of care and among providers of care involved in the emergency healthcare delivery process (Poulymenopoulou, Malamateniou and Vassilacopoulos, 2003). In addition, medical institutions are under increasing pressure to provide their staffs with anywhere, anytime access to critical patient data, including electronic health records and decision-support tools that enable evidence-based medicine. Hence, the increasing popularity of the Internet and the fast-paced advancing computing and networking technologies have fostered healthcare organizations to take advantage of the network infrastructure in order to create new channels of communication that overcome organizational boundaries. In this context, it is of primary importance to enable sharing of patient information among the various healthcare providers

4 Along with the need to enable authorized users to readily access integrated patient information at the point of care has come concern about the interoperability and meaningful integration of the data stored in existing health information systems, due to the fact that the majority of these systems are based on heterogeneous platforms, represent the data in different formats and employ different semantics. The actual solution to this problem lies in the development of interoperable computing technologies that would also be able to comprehend the semantics of the underlying data (Bicer, Laleci, Dogac and Kabak, 2005; Eccher, Purin, Pisanelli, Battaglia, Apolloni and Forti, 2006). To this end, the emerging Semantic Web technology appears to be an appealing approach (Berners-Lee, Hendler and Lassila, 2001; Kamel, Roudsari and Carson, 2002). At the same time, a number of well established standardization efforts that already exist in the medical domain, such as the Health Level Seven Clinical Document Architecture (HL7- CDA) (Dolin 2000), contribute significantly to meeting the interoperability objective. The purpose of this study is to present a prototype system which has been developed using semantic web technologies with the objective to facilitate patient information retrieval and exchange among various emergency healthcare providers within the boundaries of a health district. To this end, this paper is mainly concerned with the realization of an appropriately designed ontology, based upon the HL7-CDA standard, as a mechanism to formally describe the semantics of data classes in the emergency care domain and the semantics of properties used in web documents representing emergency patient information. In addition, the ontology is utilized as a basis for the development of semantically annotated web services which allow for the retrieval and exchange of patient information regarding emergency medical episodes. 2. Motivation The basic motivation for this research stems from our involvement in a project concerned with the development of an integrated healthcare information system within the boundaries of a health district. Part of the system is concerned with emergency care episodes starting from the time of a call for an ambulance, continuing with ambulance service management (i.e

5 ambulance dispatching and the distribution of service among hospitals) and ending when the patient is discharged from the emergency department (ED) of a hospital. In this respect, attention has also been paid on providing information support to the medical/paramedical activities performed at the site of incident, during patient transfer to a hospital (en-route treatment) and during the patient stay at the (ED) of a hospital. The stringent requirements of the system with regard to ease of use and usefulness from the users standpoint motivated this work and provided some of the background supportive knowledge for analyzing and defining emergency healthcare information needs on a sustained basis by taking the overall emergency medical service domain into account. Thus, a prototype system was developed with the objective to incorporate suitable enabling technologies for access to and exchange of integrated emergency medical information which is collected during the management of emergency medical cases by the various healthcare providers involved (e.g. health centers, ambulance services and hospital EDs). The system is based on the Semantic Web technology and is intended to ensure both structural and semantic consistency of emergency medical information irrespective of the diversity of the information systems used by the various healthcare providers while, at the same time, preserving the autonomy of the individual systems (Orgun and Vu, 2006). 3. Semantic Web: Basic Concepts The Semantic Web facilitates finding information by providing the enabling standards and technologies that allow communities to express information in ways in which it can more easily be merged and effectively searched (Berners-Lee & Miller, 2002). It is being developed as an extension of the current Web, in which information will have a well defined, machine interpretable meaning, as opposed to traditional Web where content is only intended for human consumption (Stojanovic et al., 2001). This is achieved by the semantic enrichment of both the web service functionality description and the service message description to overcome the major deficiency of the existing technologies for description, publication/discovery and - 5 -

6 messaging of Web Services (i.e. WSDL, UDDI and SOAP, respectively), which provide solely syntactic descriptions, making both providers and requesters to face problems concerning the inconsistent terminologies and the representation of the meaning of the outputs of their applications, or the meaning of their requests (McIlraith, Son and Zeng, 2001; Motta, Domingue, Cabral and Gaspari, 2003). One of the main characteristics of the semantic web is the objective of shared understanding of the concepts of a given domain, overcoming differences in terminology and allowing different users to make explicit their conceptualization of the same domain (Antoniou & van Harmelen, 2004). This is accomplished by the use of ontologies that can actually be described as a formal representation of a domain of discourse, consisted of a list of the important concepts of the domain as well as their properties and the relationships between them. Thus, ontologies facilitate communication between people and machines and support the exchange of semantics. To this end, ontologies provide a structure that annotates the contents of each clinical document with semantic information to allow retrieval of appropriate information from these documents, to facilitate integrating and exchanging information between different healthcare providers by defining the structure for its organization and to ensure consistency and correctness by formulating constraints on the content of information (Alani, Dasmahapatra, O'Hara, Shadbolt, 2003; Lassila, 2002). 4. System Architecture The prototype system developed is based upon a document-centric architecture. Hence, the information captured by the healthcare providers involved in the management of emergency medical episodes (e.g. ambulance services and hospital EDs) is expressed in the form of HL7 CDA compliant documents which are created according to the second release of the HL7-CDA (CDA-R2) standard specification (Dolin, Alschuler, Boyer, Beebe, Behlen, Biron et al., 2006). The HL7-CDA was used due to its increasing acceptance as a means for encoding clinical documents in a way that promotes structural and semantic compatibility of medical data among - 6 -

7 diverse information systems (Dolin et al., 2006; Müller, Ückert, Bürkle, Prokosch, 2005; Guo, Takada, Tanaka, Sato, Suzuki and Suzuki, et al, 2004). Figure 1 A schematic view of the system architecture is illustrated in Figure 1. In each of the healthcare organizations (e.g. hospitals and ambulance services) of a health district there exists a local information system that includes the following main components: A database server, where emergency patient data is stored. An application server, which hosts the local applications including those that are concerned with invoking the web services used for performing certain operations on emergency medical information. A web server, which receives HTTP requests to invoke the local applications and returns the results to the clients. A local security server, which defines and enforces the local security policy ensuring that certain users have the authority and privilege to access particular data stored at the local database servers. At the site of the district general hospital (DGH), there exist four additional components: A medical document repository, where emergency case data, personal (demographic) and medical, is stored as CDA-compliant XML documents which are defined in accordance with the XML schema proposed by the CDA-R2 specification. Personal data is represented in narrative form while medical data is coded using the LOINC (Logical Observation Identifiers Names and Codes, 2006), the ICD-10 (ICD-10, International Statistical Classification of Diseases and Related Health Problems, 2006) and the SNOMED (SNOMED Clinical Terms, College of American Pathologists, 2006) terminology systems. An ontology server, which hosts the ontology libraries and the ontology database (containing both the ontology description and the ontology instances). Its main purpose is to provide a formal representation of the concepts used in emergency care documents, - 7 -

8 thus allowing for a shared understanding of document contents among healthcare providers. A service repository, which hosts three web services: The first web service ( document creation web service) retrieves emergency case data collected by a healthcare provider, converts this data into a CDA-compliant XML document and sends this document as a SOAP encoded XML message to the DGH site where it is decoded and stored at the medical document repository. The second web service ( ontology instance creation web service) receives CDA-compliant XML documents form the document creation web service, represents document elements as ontology instances and stores ontology instances in the ontology database. The third web service ( information retrieval web service) receives a request from an authorized user, retrieves relevant ontology instances from the ontology database, creates a CDA-compliant XML document from these instances and sends this document to the requesting user. A global security server, which defines and enforces the district-wide security policy regarding web service invocations and subsequent access to integrated emergency medical information. It is proposed that this server is not given the sole responsibility to implement security in the health district but is implemented on top of the local security servers to enforce additional security without violating local security policies. The core of this architecture is the emergency care ontology server which is used for the formal representation of emergency care document concepts, thus allowing for the semantic compatibility and the shared understanding of document contents among healthcare providers. On these grounds, emergency care information can be made readily available to all authorized users in the health district by accessing the relevant ontology instances and converting them into CDA-compliant XML documents which are sent to requesting users

9 5. Prototype implementation To illustrate the main features of the system architecture described above, a prototype implementation involving an ambulance service, a hospital ED and a DGH is described. Thus, the prototype assumes that pre-hospital and in-hospital emergency care is provided by two healthcare providers (i.e. ambulance service and hospital ED). In essence, the system consists of three web services that are concerned with converting emergency case data into CDAcompliant XML documents, representing XML document contents in terms of an emergency care ontology and retrieving emergency care information stored as ontology instances, respectively. The web services were implemented using the NetBeans IDE platform (NetBeans IDE 4.1, 2006). The emergency medical data ontology was built using the ontology editor Protégé (Protégé, Stanford Medical Informatics Lab, 2006) and was described using the Web Ontology Language (OWL Web Ontology Language, 2006). At the highest level, the ontology hierarchy comprises four concepts that correspond to the HL7 RIM entities (HL7 Reference Information Model, 2006), the HL7 data types, the HL7 vocabularies and the HL7-CDA R2 Hierarchical Description (HD). These concepts constitute the top-classes of the ontology and are further analysed into sub-classes which describe the concepts of these main classes. The first three top-classes were included in the ontology in order to ensure its compatibility with the HL7 specification, the semantics that have been captured in the RIM and the use of standard coding systems in accordance with the HL7 V3 data types and vocabularies. The fourth top class (i.e. the CDA class) was used in order to describe the structure of emergency care documents in conformance with the hierarchical description depicted by HL7-CDA. The major concept included in this hierarchical description (e.g. Clinical Document, Author, Section, etc) were modeled as ontology classes, and associated subclasses, while their attributes were modeled as slots of the corresponding ontology classes. The concepts of the CDA-class are depicted in Figure 2. Figure 2-9 -

10 4.1 XML document creation The emergency case data collected during an emergency medical episode handled by a healthcare provider is stored at the provider s (local) database server to form the providerspecific case record (e.g. ambulance service record or ED record). At the end of case management by a healthcare provider (e.g. ambulance arrival at the ED of a hospital or patient exit from the hospital ED), the document creation web service is invoked to convert the case data collected into a CDA-compliant XML document and to send this document as a SOAP encoded XML message to the DGH site where it is decoded and stored at the medical document repository. Case data conversion into CDA-compliant XML documents is performed through a mapping mechanism whereby the attributes of the local database schema are mapped onto the corresponding attributes of the XML schema proposed by the CDA-R2 specification 4.2 Ontology instance creation Upon successful XML document creation and storage, the document creation web service invokes the ontology instance creation web service whose task is to represent CDA-compliant XML documents in terms of the ontology. To this end, the ontology instance creation web service accesses the ontology server through the Protégé API libraries (Protégé knowledge base API, 2006), uses a mapping mechanism to identify the slots of the ontology classes corresponding to XML document elements and inserts element contents into the ontology database as new instances of these slots. 4.3 Semantic information retrieval Information retrieval is performed through a semantically annotated web service ( information retrieval web service) which was implemented using the NetBeans IDE platform. The OWL-S Editor (Protégé OWL-S Editor Plugin, 2006), which is implemented as a Protégé plug-in, was used to provide the service s semantic description (i.e. service annotations that correspond to ontology class descriptions and service definition). Since OWL-S cannot currently express the binding information that WSDL captures and WSDL cannot describe the semantics of a web

11 service, both OWL-S and WSDL were used to complement each other s functionality as described in the OWL-S/WSDL grounding schema (DAML-S Coalition working document, 2003). In such a schema, OWL classes are used as the abstract types of message parts that are declared in WSDL while message formatting is specified by WSDL. On request by an authorized user, the information retrieval web service accesses the ontology server to find the relevant ontology instances, by matching the concepts included in the user s request to the concepts of the ontology, creates a CDA-compliant XML document from these instances and sends this document to the requesting user. Thus, integrated patient information (e.g. information on a specific patient) or accumulated information (e.g. information on a type of incident) may be provided on request. At this stage of the prototype development, users are prompted to submit their information retrieval requests in a CDA-compliant form through an appropriately designed application. The issue of query submission is currently under investigation. 6. Concluding Remarks Recent trends in healthcare to simultaneously contain costs and increase quality have called for new forms of healthcare delivery (e.g. continuity of care, integrated and shared care) that raise increased collaboration and cooperation requirements to ensure whole system approach and to maximize resource utilization. This creates an impetus for healthcare organizations to pay particular attention to linking their information systems in order to support cross-organizational healthcare processes by providing integrated information at the point of care as required. One important aspect of interoperability among diverse information systems is the structural and semantic compatibility of the medical information stored. This paper presents a prototype system to meet this objective in the domain of emergency care delivery in the pre-hospital and emergency department setting within the boundaries of a health district. The system is based on a document-oriented architecture and the semantic-web technology requiring that

12 emergency medical information collected during emergency medical episodes is structured in the form of CDA-compliant XML documents which are, subsequently, represented as instances of a domain-specific ontology. Access to semantically compatible emergency medical information by remotely located authorized users is provided through a semantically annotated web service whose semantic description is drawn from the ontology. Owing to favorable comments received by users of the prototype implementation described, it is intended to extend system functionality in order to support telemedicine (e.g. remote diagnostics and telemetry) and electronic delivery of health records involving primary, intermediate and secondary care through the design and implementation of various domain-specific ontologies. References [1] Alani, H., Dasmahapatra, S., O'Hara, K. and Shadbolt, N. (2003). Identifying Communities of Practice through Ontology Network Analysis, IEEE IS 18(2) (pp ). [2] Antoniou, G. and van Harmelen, F. (2004). A Semantic Web Primer, The MIT Press, Cambridge Massachusetts, London, England. [3] Berners-Lee, T., Hendler, J. and Lassila, O. The Semantic Web, Scientific American, Vol. 284, No 5 (pp ) May [4] Berners-Lee, T. and Miller, E. (2002). The Semantic Web lifts off, The news of the European Research Consortium for Informatics and Mathematics, No. 51, October 2002 [5] Bicer, V., Laleci, G., Dogac, A. and Kabak, Y. (2005). Providing Semantic Interoperability in the Healthcare Domain through Ontology Mapping, echallenges 2005, Ljubljana, Slovenia. [6] DAML-S Coalition working document (2003). Describing Web Services using OWL-S and WSDL; October 2003, [7] Dolin, R.H. (2000). Clinical Document Architecture, HL7 International Affiliates Joint Meeting, August 2000, Dresden, Germany. [8] Dolin, R.H., Alschuler, L., Boyer, S., Beebe, C., Behlen, F.M., Biron, P.V. and Shabo, A. (2006). HL7 Clinical Document Architecture, Release 2, J Am Med Inform Assoc.; Vol 13 (pp ). [9] Eccher, C., Purin, B., Pisanelli, D.M., Battaglia, M., Apolloni, I. and Forti, S. (2006). Ontologies supporting continuity of care: The case of heart failure, Comput Biol Med., Vol 36, No 7-8 (pp )

13 [10] Guo, J., Takada, A., Tanaka, K., Sato, J., Suzuki, M., Suzuki, T., et al. (2004). The development of MML (Medical Markup Language) version 3.0 as a medical document exchange format for HL7 messages, J Med Syst., Vol 28 (pp ). [11] HL7 (2006). Reference Information Model, [12] ICD-10 (2006). International Statistical Classification of Diseases and Related Health Problems, [13] Kamel Boulos, M.N., Roudsari, A.V. and Carson, E.R. (2002). Towards a semantic medical Web: HealthCyberMap's tool for building an RDF metadata base of health information resources based on the qualified Dublin Core Metadata Set, Med Sci Monit, 8(7): MT [14] Lassila, O. (2002). Towards the Semantic Web, The XML Finland 2002 conference, Helsinki, Finland, October [15] Logical Observation Identifiers Names and Codes (LOINC) (2006). [16] McIlraith, S. A., Son, T. C., Zeng, H., (2001). Semantic Web Services, IEEE Intelligent Systems, March/April 2001 (pp ). [17] Motta, E., Domingue, J., Cabral, L. and Gaspari, M. (2003). IRS II: A Framework and Infrastructure for Semantic Web Services, 2nd International Semantic Web Conference, Florida, USA, October [18] Müller, M., Ückert, F., Bürkle, T. and Prokosch, H. (2005). Cross-institutional data exchange using the clinical document architecture (CDA), International Journal of Medical Informatics, Vol 74 (pp ). [19] NetBeans IDE 4.1 (2006). [20] Orgun, B. and Vu, J. (2006). HL7 ontology and mobile agents for interoperability in heterogeneous medical information systems, Comput Biol Med., Vol 36 (7-8) (pp ). [21] OWL Web Ontology Language, [22] Poulymenopoulou, M. and Vassilacopoulos, G. (2006). A service-oriented architecture for information support to cross-organizational healthcare processes, Proceedings of MIE 2006 European Federation of Medical Informatics (pp ) Maastricht, Netherlands. [23] Poulymenopoulou, M., Malamateniou, F. and Vassilacopoulos, G. (2003). Specifying Workflow Process Requirements for an Emergency Medical Service, Journal of Medical Systems, 27(4) (pp ). [24] Protégé (2006). Stanford Medical Informatics Lab, [25] Protégé knowledge base api (2006). [26] Protégé OWL-S Editor Plugin (2006)

14 [27] SNOMED Clinical Terms (2006). College of American Pathologists, [28] Stojanovic, L., Saab, S. and Studer, R. (2001). Knowledge technologies for the Semantic Web, Proceedings of the World Conference on the WWW and the Internet (WebNet 2001) (pp ) Orlando, FL, USA

15 PERIPHERAL HOSPITAL DISTRICT GENERAL HOSPITAL Local Security Server Web Server Application Server Database Server Web Service Repository Application Server Medical Ontology Document Repository Server Global Security Server AMBULANCE SERVICE Local Security Server Web Server Application Server Database Server Internet Figure 1: System Architecture (Only district-wide components are depicted at the DGH site)

16 Figure 2: CDA-class concepts of the reference ontology