Modeling Clinical Workflows Using Business Process Modeling Notation ... healthcare task to a business process whilst ..... Intelligence in Medicine, 2009,.
Modeling Clinical Workflows Using Business Process Modeling Notation Nima Hashemian, Syed Sibte Raza Abidi NICHE Research Group, Faculty of Computer Science, Dalhousie University, Halifax, Canada {nima, sraza}@cs.dal.ca Abstract We present a semantic interoperability framework to represent Clinical Pathways (CP) as business process workflows represented using Business Process Modeling Notation (BPMN). We take a knowledge management approach whereby we represent CP as a CP ontology. To represent a CP as a process workflow we have developed a high-level semantic mapping between the CP ontology and the BPMN ontology. The ontology mapping allows the alignment of semantic relations between two ontologies and thus ensures that a clinical process defined in the CP ontology is mapped to a standard BPMN workflow element.
1. Introduction Clinical Pathways (CP) model the sequence of tasks, constraints, decision points and actor roles, to perform a specific clinical procedure, based on existing evidence and operational policies of the institution [1]. From a business process re-engineering perspective, a CP encapsulates the workflow about how to conduct a specific healthcare procedure for a specific disease/outcome in a specific healthcare setting. The term workflow can be best understood as “any work process that must go through certain steps and be handled by more than one person on its way to completion. Workflow automation relieves people of some of these tasks. Inherent in workflow are concepts of teamwork, request and approval, routing and tracking of documents, filling out forms and doing things either in series or in parallel” [2]. In order to design operationally and clinically pragmatic CP to ensure data interoperability, resource management and task prioritization, it is important to view CP as ‘specialized’ process workflows. However, the use of workflow modeling concepts in the design and optimization of CP is not yet well established, and as such there are no standard formalisms for the representation of CP in general, and CP as workflow models in particular. There is a case to explore the potential of business process modeling principles and
workflow modeling formalisms—such as Business Process Modeling Notation (BPMN), Business Process Execution Language (BPEL), UML, etc.—to design standardized CP that can be executed through workflow execution engines. We argue the use of workflow modeling formalisms to represent CP in order to clearly describe the operational aspects of clinical processes, such as (a) roles and responsibilities of care providers; (b) decision points and care options; (c) well-identified clinical/business rules; (d) operational constraints; (e) task scheduling; and (f) temporal constraints. We believe that given the complexity of CP and the unique nature of healthcare with emphasis on care quality and patient safety as opposed to cost, it is important to have a semantic description of each workflow process/task to (a) represent the operational and clinical aspects, implications and outcomes of CP; (b) establish semantically explicit relationships between the different processes/tasks to document the affects and outcomes of each task in both the general context of patient care and in the specialized context of the institution’s care environment; and (c) model each healthcare task to a business process whilst maintaining its intent and expected clinical outcomes. Nevertheless, it is a challenge to provide a semantic description of a wide range of healthcare processes that appear in CP. The Semantic Web (SW) framework provides a semantically rich knowledge modeling and representation formalism in terms of ontologies, reusability of the knowledge models, and reasoning mechanisms. Semantic web technologies offer semantically enabled knowledge representation formalisms, such as OWL ontologies, to both model and execute CP [3]. In this paper we present a semantic interoperability framework to model a CP as a business process workflow using the BPMN modeling language.
BPMN is a semi-formal modeling language that provides a graphical notation to model business processes through a workflow. To model CP as business workflows we use a workflow-oriented
BPMN ontology that contains a semaantic description of BPMN constructs. We have established a semantic interoperability (or ontology mapping) between the CP ontology and the BPMN ontology; onntology mapping allows the alignment of semantic relatiions between the clinical and workflow ontologies and tthus ensures that a clinical process defined in the C CP ontology is mapped to a standard BPMN workfloow element. We execute our BPMN-based CP in the Lombardi workflow engine (developed by IBM)), whereby users can view the execution of the CP.
2. Ontologies Used in Semanticc Interoperability Framework Our semantic interoperability fraamework allows ontology mapping between three diffeerent ontologies: (i) CP ontology representing CP; aand (ii) BPMN ontology modeling the BPMN workflow w constructs.
2.1 CP Ontology This ontology captures the healthcarre knowledge of a clinical guideline and CP. It offfers a semantic representation to instantiate a CP P to render it computerized and executable. We have used an existing CP ontology [4] that representts the knowledge in CP through 50 classes, 161 propperties and 589 instances. The CP ontology captures knowledge in a clinical practice guideline and CP. In our framework, we use the C CP ontology to instantiate an existing paper-based CP P. Given that the CP ontology is clinically-oriented it iss rather easy for health professionals to associate the cclinical concepts inherent within a CP with the conccepts in the CP ontology. This exercise allows the instaantiation of a CP via a CP ontological model.
2.2 BPMN Ontology The BPMN modeling language offfers a graphical orientation of workflows, thus making it easy for both domain experts and business process modelers to develop complex workflows. By itseelf, BPMN does not provide any formal semantics for its constructs, however there exists a OWL-DL based BPMN ontology [5] that offers a formalization of the structural components of the BPMN specification v1.1 [6]. BPMN ontology contains a set of axiom ms that describe the BPMN elements and the way in whhich they can be combined for the construction of Business Process Diagrams [7]. To model the CP as a w workflow model, it needs to be represented using a workflow model— i.e. the BPMN ontology. This is achieeved through an
ng a CP from a ontology mapping—i.e. mappin clinically-oriented CP ontology to a workflow-oriented BPMN ontology. The idea is to exttend the CP model to a process workflow model whilst maintaining the clinical aspects of a CP, yet reepresenting it using workflow constructs.
3. Semantic Interoperability y Framework: Mapping CP to Workflows Figure 1 presents the overall sttrategy for modeling CP as workflow elements. The general idea is to exploit the computerized CP, mod deled in terms of the CP ontology, to develop a workflo ow model of the CP. This is achieved by establishing a high-level ontology mapping between the two ontolo ogies—i.e. from the clinically-oriented CP ontology to the workfloworiented BPMN ontology, thuss achieving a CP represented in terms of BPMN modeling language. Semantic interoperability between n these two distinct CP representations is achieved th hrough an semantic interoperability framework thaat establishes an alignment of the semantic relation ns between the two ontologies such that a clinical pro ocess defined in the CP ontology is mapped to a standarrd BPMN workflow.
Figure 1: The methodology forr modeling CP as workflow modeling langu uage-BPMN To achieve ontology mappin ng, we specify the correspondences between classees, properties and instances between the candidatte ontologies. For instance the range of the first_step p property of the CP ontology will be map pped to the sequence_flow_target_ref prop perty of the SEQUENCE_FLOW class in the BPM MN ontology. We have defined a mapping expression e language that allows the alignment of relaations between two ontologies—the relations are reprresented in terms of mapping expressions that allow thee mapping of a CP to a business workflow represented d using the BPMN modeling language. The mappin ng expressions are written in OWL language and ex xported to the Terse RDF Triple Language (Turtle) sy yntax. The mapping expressions are represented in a ma apping ontology that basically establishes semantic maappings between the
CP and BPMN ontologies, such that the concepts in the mapping expressions will have their domain and ranges defined as concepts in the CP and BPMN ontologies. Our ontology mapping consists of four steps: Extracting and Analyzing Concepts: First, we extract all the classes, properties and constraints of both our CP and BPMN ontologies. We list all the classes and their related properties and constraints to assist in the discovery of semantic relations. The domain and range of each property is captured as well. Mapping Discovery: We discover the mapping relations between the entities (classes, properties) of our CP and BPMN ontologies. These mappings are based on the terminological technique (entity names, labels), and the interpretation of entities based on the semantic description of the entities. For instance there is a next_step property in the CP ontology for going from one step to the next step, and in the BPMN ontology there is a SEQUENCE_FLOW class that has two properties, which are the sequence_flow_source_ref and sequence_flow_target_ref properties. These two properties of the SEQUENCE_FLOW class are used to represent the flow in a workflow. Documenting: After discovering the mapping relations between our CP and BPMN ontologies, we needed to document these relations. Mapping expressions are a five-tuple M(id, T, , , R) where: • is the unique identifier for the given mapping relation. • is the type of mapping relation. We define four types of constructs in our mapping ontology (Class, Property, Class-Property, Property-Instance). • , are the entities (class, property or instance) in the source and target ontology respectively. • is the relation between the entities , . (e.g. equivalentClass, equivalentProperty). Consistency Checking: After documenting our mapping expressions, we check the consistency of our mapping ontology. We export all of our mapping expressions to an OWL ontology that we call the mapping ontology. The CP and BPMN ontologies will be imported to this mapping ontology as well. The mapping expressions in this ontology act as the bridges between these two ontologies. Importing the CP and BPMN ontologies to the mapping ontology, allows us to link our mapping expressions to these ontologies.
ontologies and report these relationships using mapping expression. We consider the following definition for ontology mapping [8]: Given two ontologies OS and OT, mapping from ontology OS to another OT means for each entity in ontology OS, we try to find a corresponding entity, which has the same intended meaning, in ontology OT. Our ontology mapping expressions contain constructs to express relations between the different entities of two ontologies: (a) Class Mapping (37 CCmappings): Mapping a class to another class (or instance of the class); (b) Property Mapping (48 PPmappings): Mapping a property (either object or data property) to another property (or instance of the property); (c) Class - Property Mapping (6 CPmappings): Mapping between a property and a class (or instance of the class); (d) Property-Instance Mapping (79 PVmappings): An instance may be mapped as a value of a target property. In our mapping expressions we used a set of OWL properties such as cardinality, union, intersection, and equivalent (owl:cardinality, owl:UnionOf, owl:IntersectionOf, , owl:equivalent, owl:one of). We provide some examples of CP-to-BPMN mapping in Table 1. Table 1 – The example relationships between the BPMN-CP ontologies CP BPMN Admission_Step Sync_Step
Decision_Option
Parallel_Gateway
Gate has_gate_out_seq_flow_ref Sequence_Flow Property
Domain
Range
condition_to_go_forward Sync_Step Condition
3.1 Mapping CP to BPMN Workflow We have defined an ontology mapping to express the relations between our CP ontology and the BPMN ontology. For ontology mapping, we try to find semantic relationships between entities of two
(User_Task) and (BPMN_Element.Category = “Admission_Step”)
Parallel_Gateway
Expression has_sequence_flow_condition Condition has_expression Expression
In our mapping expressions, we create an instance for a class, and then we map it as a vvalue of a target property, or a property/class may be mapped to a created instance of a target entity. Figgure 2 represents an example of a mapping between the two given ontologies. In CP ontology, there is a next_step property for going from one step to another step. In BPMN ontology, there is a Sequennce_Flow class, which is used to show the order of the aactivities will be performed in a process. It has ttwo properties, sequence_source_ref and sequenece__target_ref. The range of the sequence_source_ref is an object, which is the source of the flow and the range of the sequence_target_ref is another objecct, which is the target of the flow. We map the domain of the next_step property to the sequence_source_ref property of the Sequence_Flow class, and the range oof the next_step property to the sequence_target_ref prooperty.
Figure 2: Mapping the next_step property to the Sequence_Flow class The resulting mappings can be used for data transformation, web-service composition or query answering. In addition the mapping oontology can be used as the input of the merging tools tto merge the two given ontologies or to develop an exxecution engine based on these expressions. These mapping expressions develoop a high-level semantic mapping between the CP onntology and the BPMN ontology. It allows the alignm ment of semantic relations between two ontologies and tthus ensures that a clinical process defined in the C CP ontology is mapped to a standard BPMN workflow w element.
4. Concluding Remarks This research offers a solution for the modeling of CP clinically specific processes in terrms of standard business process models, and thus leveraging the standard definitions of processes too represent and optimize clinical environments byy incorporating process optimization tools. We have modeled a number of exxisting CP to a BPMN based workflow. The semanticc description of the CP tasks ensures that the transform mation of a CP to
a BPMN workflow maintains the clinical pragmatics of the CP and that it can be connected d with health data. We have developed a seman ntic interoperability framework whereby clinical processses/pathways can be conveniently mapped to business process notations thus enabling CP to be executed d and simulated for adjusting various cost functio ons. Our mapping framework allows healthcare profeessionals to model a CP using modeling constructs thaat they are familiar with, and then we transform theeir CP model to a business process model. The use of o ontologies, at both representation and mapping lev vels, allow for the semantic description of concepts and their relations, with provisions for semantic classification of healthcare concepts to ensure the right level of conceptual granularity in the repressentation scheme.
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