Biomedical subjects

P Degoulet

Publications and source records attributed to P Degoulet.

At least 19 recordsLinked to original sources

PubMed2005

François Grémy and the birth of IMIA. 1st IMIA/UMIT Medical Informatics Award of Excellence given to Professor Grémy.

In 2001 the International Medical Informatics Association (IMIA) approved the establishment of a Medical Informatics Award of Excellence to be given every three years to an individual, whose personal commitment and dedication to medical informatics has made a lasting contribution to medicine and healthcare through her or his achievements in research, education, development or applications in the field of medical informatics. The first award was given in 2004 to Prof. François Grémy, Uzes, France. As the first chairman and moderator of TC4, François Grémy is considered to be the first President of its renamed and refocused successor, the International Medical Informatics Association. The role of IFIP-TC4 in bringing together early health informaticians cannot be underestimated. Although TC4 was composed in large part of computer professionals interested in medical applications, Grémy recruited the first generation of IMIA officers and members from the medical and healthcare communities. Intellectually as well as organizationally, IFIP-TC4 was the true predecessor of IMIA.

Awards and Prizes↗

PubMed2003

Component-based mediation services for the integration of medical applications.

Allowing exchange of information and cooperation among network-wide distributed and heterogeneous applications is a major need of current health-care information systems. The European project SynEx aims at developing an integration platform for both new and legacy applications on each partner's site. We developed, in this project, mediation services based on the generic and reusable software components that facilitate the construction of an integration platform and ease the communication and the meaningful transformation among distributed and heterogeneous applications. The main component of the mediation services is named Pilot, which serves as an intelligent broker. It uses a multi-agents service model allowing the integration platform to be multi-servers. It transforms a client request into a valid high level service on the platform. Each service is broken up into several elementary steps by the Pilot. For each step, the Pilot uses an agent to realize the operation configured by the step. At runtime, the Pilot synchronizes the execution of different steps. To ease the communication and the interaction with the heterogeneous systems, an agent can integrate a Mediator. The Mediators are the communication and interpretation tools within the mediation services. We have developed a generic model that can be specialized for creating specific mediators for the different use cases. The mediator model uses two interfaces to connect the mediator with two systems that need to communicate. Each interface deals with the three aspects through three managers (the Communication Manager, the Syntax Manager and the Semantic Manager). Some ready-to-use specializations are developed for some well defined cases which can reduce the development effort. Once a manager is specialized, it can be used in different combinations with other managers to resolve different problems. The meaningful transformation is ensured on a semantic level in each mediator through the Semantic Model component. This last component allows the mapping among different vocabularies used by different systems through a shared ontology which allows the mapping process to focus on the meaning of the transformed information. We have used XML in different components of the mediation services as the interchange format and the description format. This has enhanced the flexibility of the components. The component based approach allows the generic components to be reused in different contexts and also allows the mediations services to be open to integrate other available technologies thus largely reduce the development efforts.

Artificial Intelligence↗

PubMed2001

Identification of patients at high cardiovascular risk: a critical appraisal of applicability of statistical risk prediction models.

Assessment of cardiovascular risk is widely proposed as a basis for taking management decisions about patients presenting with hypertension or hypercholesterolemia. Our aim was to critically assess the use of risk equations derived from epidemiological studies for the purpose of identifying high-risk patients. Risk equations were retrieved from the MEDLINE database and then applied to a data set of 118 patients. This data set was an evaluation study of the clinical value of the World Health Organization 1993 hypertension guidelines for the decision to treat mild hypertensive patients. We calculated agreement: 1) between equations and 2) between equations and the decision to treat taken by the physician. Most models were not applicable to our population, mainly because the original population had a narrow age range or comprised only males. Between-model agreement was better for the lower and upper risk quintiles than for the three other risk quintiles (0.58, 0.33, 0.34, 0.45, 0.70, from the lower to the upper risk quintile). When using an arbitrary threshold for defining high-risk patients (i.e. > 2% per year), we observed a huge variation of the proportion of patients classified at high risk (from 0 to 17%). There was a poor agreement between risk models and the decision to treat taken by the physician. These results suggest that risk-based guidelines should be validated before their diffusion.

Antihypertensive Agents↗

PubMed2001

Elaboration and formalization of current scientific knowledge of risks and preventive measures illustrated by colorectal cancer.

OBJECTIVES: Present the method used to elaborate and formalize current scientific knowledge to provide physicians with tools available on the Internet, that enable them to evaluate individual patient risk, give personalized preventive recommendations or early screening measures. METHODS: The approach suggested in this article is in line with medical procedures based on levels of evidence (Evidence-based Medicine). A cyclical process for developing recommendations allows us to quickly incorporate current scientific information. At each phase, the analysis is reevaluated by experts in the field collaborating on the project. The information is formalized through the use of levels of evidence and grades of recommendations. GLIF model is used to implement recommendations for clinical practice guidelines. RESULTS: The most current scientific evidence incorporated in a cyclical process includes several steps: critical analysis according to the Evidence-based Medicine method; identification of predictive factors; setting-up risk levels; identification of prevention measures; elaboration of personalized recommendation. The information technology implementation of the clinical practice guideline enables physicians to quickly obtain personalized information for their patients. Cases of colorectal prevention illustrate our approach. CONCLUSIONS: Integration of current scientific knowledge is an important process. The delay between the moment new information arrives and the moment the practitioner applies it, is thus reduced.

Colorectal Neoplasms↗

PubMed2001

Integrating medical applications in an open architecture through generic and reusable components.

Allowing exchange of information and cooperation among network-wide distributed and heterogeneous applications is a major need of current health care information systems. It forces the development of open and modular integration architectures. Major issues in the development include defining a flexible and robust federation model, developing interaction and communication facilities as well as the mechanism insuring semantic interoperability. We developed generic and reusable software components to ease the construction of any integration platform. The Pilot and the Mediator Service components facilitate the execution of services and the meaningful transformation of information. They have been tested in the context of the SynEx European project to construct a multi-agents based integration architecture. The possibility of such architectures to take into account the issue of semantic interoperability is further discussed.

Computer Communication Networks↗

PubMed2001

Expression and meaning of medical language: building an epistemological framework for the study of semantic distance.

The use of language for communication purposes introduces a semantic gap in data processing. We have developed a new tool called semantic distance to overcome this gap. A previous presentation of our tool was based on an empirical approach. Here, we examine the properties and theoretical foundation of semantic distance from a rationalistic perspective. We present an epistemological framework to explain the meaning of semantic distance. As a tool, the purpose of semantic distance is the exchange of data or knowledge based on linguistic expressions between software components. We propose a review of the relationship between language and its representation for data processing based on the underlying philosophical assumptions. Description logic is a new paradigm in the medical informatics community to express relations between terms in "is-a" hierarchies. The utility of semantic distance is compared to description logic for communication purposes in different use cases.

Knowledge↗

PubMed2001

Computerization of guidelines: towards a "guideline markup language".

Medical decision making is one of the most difficult daily tasks for physicians. Guidelines have been designed to reduce variance between physicians in daily practice, to improve patient outcomes and to control costs. In fact, few physicians use guidelines in daily practice. A way to ease the use of guidelines is to implement computerised guidelines (computer reminders). We present in this paper a method of computerising guidelines. Our objectives were: 1) to propose a generic model that can be instantiated for any specific guidelines; 2) to use eXtensible Markup Language (XML) as a guideline representation language to instantiate the generic model for a specific guideline. Our model is an object representation of a clinical algorithm, it has been validated by running two different guidelines issued by a French official Agency. In spite of some limitations, we found that this model is expressive enough to represent complex guidelines devoted to diabetes and hypertension management. We conclude that XML can be used as a description format to structure guidelines and as an interface between paper-based guidelines and computer applications.

Decision Making, Computer-Assisted↗

PubMed2001

From paper-based to electronic guidelines: application to French guidelines.

In order to develop an internet-based decision support system, making available for French general practitioners several prevention guidelines is was necessary to implement paper based guideline. We propose a framework allowing to transform paper based practice guideline into their electronic form. Three different problems were identified: computability (e.g. determinism of the eCPG), logic (e.g. ambiguities when combining Booleans operators) and external validity (i.e. stability of decision for variations around thresholds and proportion of subjects classified in the various terminal nodes). The last problem concerned documentation of evidence: the level of evidence was associated only with the terminal decision node and not with the pathway through the decision tree. We concluded that computerisation of guidelines is not possible without expertise or authors advice. To improve computability it is necessary to provide authors with a framework that checks ambiguities, and logical errors.

Algorithms↗

PubMed2001

Guideline development: focus on breast cancer screening in the EsPeR project.

We describe in this paper, the implementation of a clinical practice guideline focused on breast cancer screening. Our aim in conceiving such a computerized guideline was first to help general practitioners in appreciating the risks their female patients might develop breast cancer and secondly to suggest them the screening measures adapted to each particular case. This implementation enables us to present our general methodology to elaborated and promulgate guidelines within the EsPeR project. This methodology aims at providing guidelines based on knowledge validated according to the EBM principles, that can be used in real time and updated according to current knowledge.

Algorithms↗

PubMed2001

Logistic regression model: an assessment of variability of predictions.

Risk prediction models available for cardiovascular prevention are statistical or based on machine learning methods. This paper investigates whether the logistic regression method can be considered as reference for validation of other methods. In order to test the stability of the predictions using this method, we performed two types of analyses on 50 random training and test samples drawn from the same database. In first analyses three models were obtained by forced entry of different sets of four variables. In second analyses, models were built with increasing number of predictive variables. The predictive performance was assessed by the area under the ROC curve. Although across-samples variability is low for a given model, it is large enough to lead to wrong conclusions when comparing different prediction methods. We also suggest that a low events-per-variable ratio alters the stability of a model's coefficients but does not affect the variability of prediction performance.

Area Under Curve↗

PubMed2001

Modeling uncertainty in computerized guidelines using fuzzy logic.

Computerized Clinical Practice Guidelines (CPGs) improve quality of care by assisting physicians in their decision making. A number of problems emerges since patients with close characteristics are given contradictory recommendations. In this article, we propose to use fuzzy logic to model uncertainty due to the use of thresholds in CPGs. A fuzzy classification procedure has been developed that provides for each message of the CPG, a strength of recommendation that rates the appropriateness of the recommendation for the patient under consideration. This work is done in the context of a CPG for the diagnosis and the management of hypertension, published in 1997 by the French agency ANAES. A population of 82 patients with mild to moderate hypertension was selected and the results of the classification system were compared to whose given by a classical decision tree. Observed agreement is 86.6% and the variability of recommendations for patients with close characteristics is reduced.

Decision Making, Computer-Assisted↗

PubMed2001

A consensus approach to maintain a knowledge based system in pathology.

The IDEM (Images and Diagnosis from Example in Medicine) software is a computerized environment able to store unambiguous descriptions of histopathologic images from pathologists. Medical imaging could benefit from such environments if they can easily and continuously be maintained. Within the IDEM environment, we developed a knowledge management module coupled with a consensus module to support knowledge acquisition and maintenance by the experts of the domain. Two pathologists, a senior and junior pathologist, reviewed fifty-three cases of breast pathology. Our findings indicate 1) that the IDEM knowledge management module allows experts to describe images by selecting terms and defining new ones if necessary, allowing the construction of a glossary for the domain and 2) that the consensus module, developed to store valid multi-experts cases, contributes also to validate new terms of the glossary and to refine semantic distance between terms. Such methodology could be applied to others highly evolving medical domains.

Artificial Intelligence↗

PubMed2000

The use of the personalized estimate of death probabilities for medical decision making.

Data coming from the French national statistics on the cause of deaths are used to calculate the probabilities of death from pathologies. These probabilities are calculated according to age, sex, and place of residence of the patient to "personalize" the estimate. This individual prediction of the risk of death is proposed for pathologies for which the feasibility and the utility of prevention measures had been demonstrated. Relative risks of death according to the socioprofessional category, which are coming from the scientific literature, are used to adjust the probabilities of death as a function of the patient socioprofessional category. The aim of this work is to guide a scientist toward a prevention strategy according to the age and characteristics of patient. The use of computers by the scientists will make possible the diffusion of such tool of prediction to improve a personalized prevention.

Cause of Death↗

PubMed2000

[From knowledge to clinical practice: the introduction of evidence-based medicine].

INTRODUCTION: The paper presents the new paradigm for medical practice which has been emerging for a decade: evidence-based medicine. CURRENT KNOWLEDGE AND KEY POINTS: The paradigm proposes new skills for the physicians, de-emphasizing intuition and empiricism in medical practice, and proposes the intensive use of medical literature for the medical practice. FUTURE PROSPECTS AND PROJECTS: The article presents the main characteristics of the approach which is raising new important questions about the evolution of medical practice and the validity of the paradigm.

Delivery of Health Care↗

PubMed2000

Integration of medical applications: the 'mediator service' of the SynEx platform.

Interoperability is a key issue and a long-term domain of research for distributed healthcare information systems. The SynEx European project provides open and standard integration platform for both new and legacy medical applications. It aims to provide access to hospital information services, patient records, and to medical knowledge, in a seamless way, hiding the distribution aspects and the heterogeneity of the underlying systems. In this study, we describe the SynEx 'mediator service', a software engineering component, that is used to facilitate the development of mediators between any pair of SynEx components and to manage the corresponding interchange messages. Both a C++ library and a Java package of a generic mediator model are provided with several ready-to-use specialisations for well-defined use. The use of the XML technology as a powerful data interchange format and as an efficient data structure converter is proposed and discussed.

Computer Communication Networks↗

PubMed2000

[Can the degree of renal artery stenosis be automatically quantified?].

The objective of the reported study is to validate a computer system, QUASAR, dedicated to the quantification of renal artery stenoses. This system estimates automatically the reference diameter and calculates the minimum diameter to compute a degree of stenosis. A hundred and eighty images of atheromatous stenoses between 10% and 80% were collected from two French independent protocols. For the 49 images of the EMMA protocol, the results from QUASAR were compared with the visual estimation of an initial investigator and with the results from a reference method based on a panel of fixe experienced experts. For the 131 images of the ASTARTE protocol, the results from QUASAR were compared with those from a semi-automatic quantification system and with those from a system based on densitometric analysis. The present work validates QUASAR in a population of narrow atheromatous stenoses (> 50%). In the context of the EMMA protocol, QUASAR is not significantly different from the mean of the fixe experts. It is unbiased and more precise than the estimation of a single investigator. In the context of the ASTARTE protocol, there is no significant difference between the three methods for the stenoses higher than 50%, however, globally, QUASAR surestimates significantly (up to 10%) the degree of stenosis.

Aged↗

PubMed2000

Using semantic distance for the efficient coding of medical concepts.

OBJECTIVE: To use the notion of semantic distance to find the nearest neighbors of a medical concept in a controlled vocabulary. MATERIAL AND METHOD: 392 concepts from the cardiovascular chapter of the ICD-10 were projected on the axes of SNOMED III. Distances were measured on each axis and the resulting distance was found using a Lp norm. RESULTS: The distance between a set of ischemic diseases and a set of non-ischemic diseases was significant (p < 0.0001). Our method was validated by finding the k nearest neighbors of ten different diagnoses from the ICD-10 cardiovascular chapter. DISCUSSION: The availability of SNOMED-RT should improve our method. Several more steps are necessary to provide an ideal coding tool.

Cardiovascular Diseases↗

PubMed2000

Models to predict cardiovascular risk: comparison of CART, multilayer perceptron and logistic regression.

The estimate of a multivariate risk is now required in guidelines for cardiovascular prevention. Limitations of existing statistical risk models lead to explore machine-learning methods. This study evaluates the implementation and performance of a decision tree (CART) and a multilayer perceptron (MLP) to predict cardiovascular risk from real data. The study population was randomly splitted in a learning set (n = 10,296) and a test set (n = 5,148). CART and the MLP were implemented at their best performance on the learning set and applied on the test set and compared to a logistic model. Implementation, explicative and discriminative performance criteria are considered, based on ROC analysis. Areas under ROC curves and their 95% confidence interval are 0.78 (0.75-0.81), 0.78 (0.75-0.80) and 0.76 (0.73-0.79) respectively for logistic regression, MLP and CART. Given their implementation and explicative characteristics, these methods can complement existing statistical models and contribute to the interpretation of risk.

Artificial Intelligence↗