We describe the task-based approach we have taken to define guideline-based decision-support services that the EON system provides. We categorize uses of guidelines in patient-specific decision support into a set of generic tasks-decision-making, specification of work to be performed, interpretation of data, setting goal, and issuance of alert and reminders-that can be solved using various techniques. Our model contains modeling constructs required for representing knowledge used by these techniques. These constructs form a toolkit from which modeling solutions for guideline tasks can be selected. Based on the tasks and the guideline model, we define a guideline-execution architecture and a model of interactions between a decision-support server and clients that invoke services provided by the server. These services use generic interfaces derived from guideline tasks and their associated modeling constructs. We describe two implementations of these decision-support services and discuss how this work can be generalized. We argue that a well-defined specification of guideline-based decision-support services will facilitate sharing of tools that implement computable clinical guidelines.
