Introduction

openEHR provides specifications for various models and languages to address the area of process and guideline-driven healthcare. These are as follows:

Together these enable the authoring of care pathways, guidelines, executable care plans and in-application active forms. There is also an existing guideline language, Guideline Definition Language 2 (GDL2), which defines an earlier self-standing guideline format, on which some self-standing guidelines solutions are built. In some circumstances, such systems may be equivalently implemented in the future using TP/DL/EL instead of GDL2.

Many of the formal semantics of the DLM formalism come from experience with existing GDL2 deployments.

The openEHR Task Planning specification is conceptually close to the YAWL language (Yet Another Workflow Language) [1], as well as to the OMG BPMN and CMMN standards, which support different flavours of workflow. Many ideas were adopted and/or adapted from YAWL, of which the only deficiencies are: being agnostic on rule language and data persistence (both of central importance in healthcare IT), and no longer being actively maintained. The BPMN and CMMN standards have a weaker theoretical foundation, and were not originally conceived as being business analysis rather than executable formalisms; they also have only limited worker definition and allocation semantics, are weak on data persistence and have a rules expression formalism (DMN) that is relatively under-developed or tested in healthcare.

openEHR GDL2 and the more recent Decision Language may be compared to other languages developed in the health arena for expressing medical logic and rules, including HL7 Arden Syntax, Guideline Interchange Format [2], ProForma [3], as well as Decision Languages such as HL7 Gello and OMG DMN, and the HL7 Clinical Quality Language (CQL). These languages were not directly used, for various reasons including:

Nevertheless, the design approach of Arden provided useful inspiration for the formalism described here, and indeed the Subject Proxy approach used in openEHR may be understood as a solution to the so-called 'curly braces problem' of Arden [4], i.e. the need to be able to bind rule logic to real-world variables. The ProForma language and underlying scientific analysis also has much to recommend it, and has been used as an important theoretical input to the specifications developed for openEHR. The HL7 CQL standard, although lacking a workflow language, provided useful insights including on temporal logic operators (originally described in [5]), data binding and general expression language design.

The following table indicates the approximate correspondences between the openEHR process specifications and various published standards.

The OMG group of standards are starting (as of 2020) to find use in the healthcare arena under the banner BPM+.

Numerous publications have appeared over the last 30 years on process automation, decision support and related subjects, including within healthcare. A small number of seminal publications have been particularly valuable in the development of the openEHR Process-related specifications, including [6] and [1].

The first of these presented an often-cited diagram capturing the existence and challenges of representation between the various elements needed in computable guideline technology, shown below.

The authors enumerated many challenges directly relevant to the specifications described here, including the following:

This paper presaged the notion of the 'vritual medical record', which itself may be seen as a precursor for the Subject Proxy concept used here.