From Classifications and Coding systems to Ontology: the role of a CEN standard: The categorial structure

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1 From Classifications and Coding systems to Ontology: the role of a CEN standard: The categorial structure Jean Marie RODRIGUES a, Béatrice TROMBERT PAVIOT a, Caroline MARTIN a and Paul VERCHERIN a. a Département de Santé Publique et Information Médicale, Université of Saint Etienne, France Abstract. The presentation recalls the limits of terminologies of 2 coding systems for surgical interventions: the French CCAM and the Australian international ICHI as assessed by Galen ontology driven tools. Such an ontology associated with natural language processing allows to analyse inconsistencies and ambiguities of natural language expressions when considering the reality of surgical interventions.on the other hand there is an increasing need for international comparisons and cooperation across the most advanced and less developed countries for instance for Electronic Health Record safety, trans border migration of population, case mix and procedure payment et. As no reasonable person is proposing to standardise the linguistic expressiveness of different health care professionals and of the citizens the European Standard Body CEN has developed since 1990 through is Technical committee 251 and its working group 2 an approach named Categorial structure which is presented here with the different application fields. The role of this tool is addressed in relation with ontology. It is proposed not as ontology but as a step to link biomedical terminology to ontology. Such a standard is an easy and provisional condition to evolve from functional to full semantic interoperability which needs a rigorous ontology. Keywords: Classification, Coding system, Terminology; Ontology, Standards, Categorial structure. 1. Introduction The semantic interoperability is becoming the top challenge to the implementation of the electronic healthcare record. There are a lot of divergent initiatives addressing the different aspects of interoperability: information models (HL7 Reference Information Model RIM, CEN Continuity of care and EHRcom, et.), architectures (HL7 Common Document Architecture CDA, CEN EHRcom, et.), context (Templates or Archetypes, et.) and the forest of pragmatic or reference clinical terminologies for different national languages. Since 15 years a new approach has challenged the ability of such type of technological approach to support unambiguous exchanges of meaning through computers. These approaches have been enabled by advances in computer sciences, artificial intelligence, linguistic and philosophy. They are based on terminology server architecture making available knowledge bases representing multihierarchies of concepts associated by semantic subsuming the logical meaning of their relations. These knowledge representations are named ontology [1] which is a term

2 coming from metaphysics but are in fact formal logic describing mathematical expressions. During the same period most of developed countries have lasted to maintain, update and modify their own coding systems for procedures and national adaptations of ICD to manage and to fund the healthcare delivery. This has hampered the coordination between countries and prevented the less developed ones to use the information tools available in the most advanced ones.the most significant efforts for procedures were done in Australia with ACHI (Australian Classification of Health Interventions) or ICD10 AM [2]and France with CCAM (for Classification Commune des Actes Médicaux)[3] The application of ontology driven tools to the biomedical terminology of the coding systems is very useful to show that it is not possible to extract full knowledge from the pragmatic terminology used by the professionals and in the future by the citizens : we show some examples in Part 2. One solution very often proposed by new comers to the field is the standard. Hopefully after some researches no reasonable person is proposing to standardise the linguistic expressiveness of different health care professionals and of the citizens.the standard approach named categorial structure elaborated and developed by the European Standard Body CEN TC 251 WG2 (Comité Européen de Normalisation Technical Committee 251 Working Group 2 ) in part 3 is addressed from the view of the relation of this standard approach with biomedical terminology and ontology in part Material and method 2.1. Material We have applied the GALEN ontology tools to 2 different coding systems for interventions: the French CCAM and the Australian ICHI (International Classification of Health Intervention) [2] CCAM stands for Classification Commune des Actes Médicaux and has been developed by the French health authorities for Case-mix and procedures payment during the 90s. ICHI stands for International Classification of Health Intervention and has been designed by the National Centre for Classification in Health of Australia primarily to meet the needs of countries using ICD-10, but that do not presently collect intervention/procedure data, and which need access to a simple classification system. Following the interest for the Galen CCAM developments in several countries and in agreement with WHO Classifications and terminology unit, Department of Measurements and Health information Systems (MHI) the Galen network extended to Portuguese speaking domain specialists decided to test the method on the available ICHI beta version.

3 2.2. Method The GALEN formal representation [4] is made of around entities, with 800 included links and we combined it with a semiformal representation tool named Claw and a linguistic interface named NLP [5]. This set is what we call an ontology driven tool. This representation has allowed checking the consistence of the terminology proposed by the domain expert consensus with the knowledge embedded in the GALEN model. Among results presented elsewhere [5] the most stable conclusion is the inability of terminology alone to produce consistent knowledge as exemplified by Table 1 and Table 2 concerning CCAM and Table 3 concerning ICHI. 2.3 Results Table 1. Initial rubric in English CCAM "Extra corporeal Lithotrypsy for a kidney pelvis calculus with ultrasonography monitoring and ureteral draining " Initial rubric in French CCAM "Lithotritie extra-corporelle d une lithiase pyélique sous repérage échographique et drainage urétéral" Intermediate dissection MAIN extracting ACTS_ON calculus HAS_LOCATION renal pelvis BY_TECHNIQUE fragmenting ACTS_ON calculus HAS_LOCATION renal pelvis BY_MEANS_OF extra_corporeal_lithotrypsy_device BY_TECHNIQUE imaging ACTS_ON renal pelvis BY_MEANS_OF ultrasound machine TO_ACHIEVE control BY_TECHNIQUE installing ACTS_ON drain HAS_DESTINATION ureter Generations in natural language English : Extracting of a renal pelvis calculus by fragmenting the renal pelvis calculus with an extra corporeal lithotripsy device, by imaging the renal pelvis by an ultrasonography to control and by installing a drain in the ureter. French : Extraction d un calcul du bassinet par fragmentation du calcul du bassinet avec un lithotripteur extra corporel,imagerie du bassinet par échographie de repérage et installation d un drain dans l uretère. Table 2.

4 Initial rubric in English CCAM "Extra corporeal Lithotrypsy for a lumbar ureter calculus with ultrasonography monitoring and without ureteral draining " Initial rubric in French "Lithotritie extra-corporelle d une lithiase urétérale lombaire sous contrôle échographique sans drainage urétéral" Intermediate dissection MAIN fragmenting ACTS_ON calculus HAS_LOCATION lumbar_ureter BY_MEANS_OF extra_corporeal_lithotrypsy_device BY_TECHNIQUE imaging ACTS_ON lumbar_ureter BY_MEANS_OF ultrasound machine TO_ACHIEVE control WITHOUT installing ACTS_ON drain HAS_DESTNATION ureter Generations in natural language English : Fragmenting a lumbar ureter calculus with an extra corporeal lithotripsy device with imaging lumbar ureter by an ultrasonography to control without installing a drain in the ureter. French :Fragmentation d un calcul de uretère lombaire avec un lithotripteur extra corporel et imagerie de l uretère lombaire par échographie de repérage sans installation d un drain dans l uretère. The same word Lithotrypsy (French Lithotritie) describes 2 very different actions for the patient in reality. In Table 1 it means extracting a calculus from the body of the patient by 3 sub processes: fragmenting the calculus, imaging the renal pelvis and installing a drain in the ureter. The action results in the exit of the calculus from the body. In Table 2 it means only fragmenting the calculus and imaging the lumbar ureter: the fragmented calculus is left in the body (expecting it will be expelled by the normal urinary flow).the action results in keeping the calculus in the body. The following example is stressing the inconsistent usage of the term arthroplasty within ICHI across the different rubrics of the same biomedical classification in Table 3. Table 3 QA Inconsistent usage of the same term: Arthroplasty Initial rubric in English ICHI-Chapter XV, 1518 Arthroplasty of knee Natural language generations English: Repairing of the knee joint Portuguese: Reparação da articulacão do joelho

5 French: Réparation de l articulation du genou Initial rubric in English ICHI-Chapter XV, 1519: Arthroplasty of knee with bone graft to femur or tibia Natural language generations English: Replacement of the knee joint with a prosthesis of the knee joint, with installation of bone graft tissue in the femur or the tibia by means of harvesting bone Portuguese: Substituicão da articulacâo do joelho com una prótese da articulacão do joelho, com instalacão de transplante de tecido de osso no fémur ou na tíbia por meio de colhida /colheita do osso. French: Remplacement de l articulation du genou par une prothèse de l articulation du genou avec mise en place de tissu osseux greffé sur le fémur ou le tibia au moyen de prélèvement osseux Initial rubric in English ICHI-Chapter XV, 1489 Arthroplasty of hip joint Natural language generations English :Repairing of the hip joint. Portuguese: Reparação da articulacão do quadril/anca. Reparação plástica ou substituição da articulação da anca com uma prótese? French: Réparation de l articulation de la hanche. Réparation plastique ou Prothèse de hanche? Within the rubrics 1518 and 1519 the same term arthroplasty is used once to define a limited plastic repairing of the joint or the complete replacement of the knee but the 2 rubrics do exist and may allow the separation of these two different intervention classes. Unfortunately, for the hip joint there is only one rubric with the term arthroplasty, and it is not possible to separate these two types of intervention which are completely different in reality. These examples show that it is not possible to develop a consistent reality based biomedical terminology without ontology driven tools. 3. CEN standardisation in terminology: Categorial structure 3.1Brief history

6 The standardisation in health informatics started in 1990, in Europe with CEN (Comité Européen de Normalisation) and internationally in 1998 with ISO (International Standard Organisation). The process aimed to the electronic health record of the patients (EHR) was encompassing messages, architecture, security, and a definition of the minimum requirements a terminology (controlled vocabularies, nomenclatures, coding systems and classifications) must comply with to support interoperability between different informatics systems. It was clearly stated at the beginning and confirmed several times that it was not realistic to impose a standard terminology to health care professionals from different medical specialties and speaking different natural languages even if you advocate that it is a reference terminology or a pragmatic terminology. On the other hand it was assessed as impossible at that time to propose a standard for the whole clinical knowledge supporting clinical terminologies due to its volume, its quickly evolving content and the lack of agreement on a shared methodology to represent it. For these reasons it was decided to develop a minimal semantic structure describing only the main properties of the different artefacts used as terminology: a restricted model of knowledge. 3.2 Categorial structure Since MOSE [6] a Categorial structure (or reference terminology model) can be defined as a minimal set of domain constraints for representing terminology systems in a precise domain to achieve a precise goal. It is a semantic representation. Four information types are needed: a) The list of semantic categories, b) The goal of the Categorial structure, c) The list of relevant associated semantic links or relations, d) The minimum combinatorial rules or domain constraints allowing the generation and validation of well formed terminology systems. This methodology has been applied by CEN for the coding systems and classifications of surgical procedures [7] and by ISO for nursing diagnostics and procedures [8]. The standardising processes are on going for clinical laboratories, medical devices, medicinal products, continuity of care and anatomy. 4. Discussion It is important to clear the position of the Categorial structure between the different terminology artefacts commonly used and an ontology needed to insure the consistency of the knowledge exchange through computers. We use a refined definition of ontology for terminology which has been proposed by members of 2 consortiums of FP6 SemanticHEALTH and RIDE following required by the European Union Commission [9].Ontology (for terminology) was defined as a representation of some pre-existing domain of reality which

7 (1) Reflects the properties of the entities within its domain in such a way that it obtains a systematic correlation between reality and the representation itself and the non ambiguous comparison between different representations of the reality (2) Is intelligible to a domain expert, (3) Is formalised in a way that allows it to support automatic information processing. The CEN Categorial structure fulfils the point 2 and partly the point 1 for it gives the categories and the relations between the categories but does not allow a systematic correlation between representations and between the representation and the reality. Finally it is not formalized enough to support automatic information processing. On the other hand this minimal structure supporting the terminology artefacts gives a common framework to analyze the terminology artefacts properties, their basic relations and their comparison. It must be considered as the reasonable level of standardisation to day. But it is only the first step to ontology representations and their alignment to reduce terminology artefacts gaps and inconsistencies. It shall support the process towards a further phase: a common worldwide shared biomedical ontology necessary for a full semantic interoperability. This future development will probably challenge the frontier of standards in biomedical terminology. Acknowledgements We wish to thank our partners in the GALEN program and namely the University of Manchester, the University of Nijmegen and the University of Geneva, WHO Classifications and terminology unit, Department of Measurements and Health information Systems (MHI) and Stefan Schultz for his Portuguese language expertise References [1] Gruber T. A translation approach to potable ontology specifications. Knowledge Acquisition 1993; 5(2): [2] National Centre for Classification in Health see [3] Agence Technique de l Information Hospitalière see [4] [5] Trombert-Paviot B, Rodrigues J-M, Rogers J, Baud R, van der Haring E, Rassinoux A-M, Abrial V, Clavel L, Idir H. GALEN: a third-generation terminology tool to support a multipurpose national coding system for surgical procedures. International Journal of Medical Informatics 2000; 58 9: [6] CEN/TC251/ENV 12264:1995 Medical informatics - Categorial structures of concepts systems. Further EN 12264:2005 Health informatics - Categorial structures of concepts systems. [7] CEN AFNOR EN NF 1828:2002. Health informatics Categorial Structure for classifications and coding systems of surgical procedures.

8 [8] EN ISO Integration of a Reference Terminology Model for Nursing. [9] Semantic Interoperability seminar.brussels February 2005 Address for correspondence JM Rodrigues, CHU de St Etienne, SSPIM, Hôpital St Jean Bonnefonds, St Jean Bonnefonds, France. rodrigues@univ-st-etienne.fr