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Biomedical subjects

N F de Keizer

Publications and source records attributed to N F de Keizer.

15 recordsLinked to original sources
PubMed2007

The quality of evidence in health informatics: how did the quality of healthcare IT evaluation publications develop from 1982 to 2005?

OBJECTIVE: To obtain an overview of study designs and study methods used in research evaluating IT in health care, to present a list of quality criteria by which all kinds of reported evaluation studies on IT systems in health care can be assessed, and to assess the quality of reported evaluation studies on IT in health care and its development over time (1982-2005). METHODS: A generic 10-item list of quality indicators was developed based on existing literature on quality of medical and medical informatics publications. It is applicable to all kind of IT evaluation papers and not restricted to randomized controlled trials. One hundred and twenty explanatory papers evaluating the effects of an IT system in health care published between 1982 and 2005 were randomly selected from PubMed, the study designs and study methods were extracted, and the quality indicators were used to assess the quality of each paper by two independent raters. RESULTS: The inter-rater variability of scoring the 10 quality indicators as assessed by a pre-test with nine papers was good (K=0.87). There was a trend towards more multi-centre studies and authors coming more frequently from various departments. About 70% of the studies used a design other than a randomized controlled trial (RCT). Forty percent of the studies combined at least two different data acquisition methods. The quality of IT evaluation papers, as defined by the quality indicators, was only slightly improving in time (Spearman correlation coefficient [rs]=0.19). The quality of RCTs publications was significantly higher than the quality of non-RCT studies (p<0.001). CONCLUSION: The continuous and dominant number of non-RCT studies reflects the various approaches applicable to evaluate IT systems in health care. Despite the increasing discussion on evidence-based health informatics, the quality of published evaluation studies on IT interventions in health care is still insufficient in some aspects. Journal editors and referees should take care that reports of evaluation on IT systems contain all aspects needed for a sufficient understanding and reproducibility of a paper. Publication guidelines should be developed to support more complete and better publications of IT evaluation papers.

Europe↗
PubMed2006

A framework for characterizing terminological systems.

OBJECTIVES: The notion of a terminological system (TS) is complex due to the broad range of systems, applications, and clinical domains. A uniform approach to describe the characteristics of TSs is lacking. This impedes furthering understanding, applicability, mutual comparison and development of TSs. For these reasons we propose a terminological systems characterization framework. METHODS: Relevant issues pertaining to TSs and terminology servers have been extracted from literature describing requirements and functionality of TSs. From these issues, features have been distilled and further refined. A categorization has been developed to provide a convenient arrangement of these features. RESULTS: The framework distinguishes between application-dependent and application-independent features of TSs. Definitions are provided for measures of content coverage, which was identified as the only application-dependent feature. Application-independent features are categorized along two axes: their respective type of TS and the particular element within that system, i.e. the formalism, the content, or the functionality. For each feature we provide an explicit question, the answer to which yields a feature value. The framework has been applied to SNOMED CT and the CLUE browser. CONCLUSIONS: We present and apply a framework to support a feature-based characterization of terminological systems. Standardized methods for content coverage studies reduce the effort of assessing the applicability of a TS for a specific clinical setting. A two-axial categorization provides a convenient arrangement of the large number of application-independent features. Application of the framework increases comparability of terminological systems. This framework may also help TS developers determine how their system can be improved.

Medical Informatics Applications↗
PubMed2005

Reliability and accuracy of Sequential Organ Failure Assessment (SOFA) scoring.

OBJECTIVE: The Sequential Organ Failure Assessment (SOFA) score was developed to quantify the severity of patients' illness, based on the degree of organ dysfunction. This study aimed to evaluate the accuracy and the reliability of SOFA scoring. DESIGN: Prospective study. SETTING: Adult intensive care unit (ICU) in a tertiary academic center. SUBJECTS: Thirty randomly selected patient cases and 20 ICU physicians. MEASUREMENTS AND MAIN RESULTS: Each physician scored 15 patient cases. The intraclass correlation coefficient was .889 for the total SOFA score. The weighted kappa values were moderate (0.552) for the central nervous system, good (0.634) for the respiratory system, and almost perfect (>0.8) for the other organ systems. To assess accuracy, the physicians' scores were compared with a gold standard based on consensus of two experts. The total SOFA score was correct in 53% (n = 158) of the cases. The mean of the absolute deviations of the recorded total SOFA scores from the gold standard total SOFA scores was 0.82. Common causes of errors were inattention, calculation errors, and misinterpretation of scoring rules. CONCLUSIONS: The results of this study indicate that the reliability and the accuracy of SOFA scoring among physicians are good. We advise implementation of additional measures to further improve reliability and accuracy of SOFA scoring.

Coma↗
PubMed2005

Methods for evaluation of medical terminological systems--a literature review and a case study.

OBJECTIVES: The usability of terminological systems (TSs) strongly depends on the coverage and correctness of their content. The objective of this study was to create a literature overview of aspects related to the content of TSs and of methods for the evaluation of the content of TSs. The extent to which these methods overlap or complement each other is investigated. METHODS: We reviewed literature and composed definitions for aspects of the evaluation of the content of TSs. Of the methods described in literature three were selected: 1) Concept matching in which two samples of concepts representing a) documentation of reasons for admission in daily care practice and b) aggregation of patient groups for research, are looked up in the TS in order to assess its coverage; 2) Formal algorithmic evaluation in which reasoning on the formally represented content is used to detect inconsistencies; and 3) Expert review in which a random sample of concepts are checked for incorrect and incomplete terms and relations. These evaluation methods were applied in a case study on the locally developed TS DICE (Diagnoses for Intensive Care Evaluation). RESULTS: None of the applied methods covered all the aspects of the content of a TS. The results of concept matching differed for the two use cases (63% vs. 52% perfect matches). Expert review revealed many more errors and incompleteness than formal algorithmic evaluation. CONCLUSIONS: To evaluate the content of a TS, using a combination of evaluation methods is preferable. Different representative samples, reflecting the uses of TSs, lead to different results for concept matching. Expert review appears to be very valuable, but time consuming. Formal algorithmic evaluation has the potential to decrease the workload of human reviewers but detects only logical inconsistencies. Further research is required to exploit the potentials of formal algorithmic evaluation.

Evaluation Studies as Topic↗
PubMed2003

[Intensive care medicine in the Netherlands, 1997-2001. I. Patient population and treatment outcome].

OBJECTIVE: To describe the patients admitted to intensive care units (ICUs) in the Netherlands between 1997-2001 and the treatment outcome. DESIGN: Descriptive. METHOD: For the years 1997-2001, prospective admission and discharge data as well as all data necessary for calculating prospective severity of illness scores (e.g. APACHE II and SAPS II) were collected for all patients that were admitted to 18 ICUs participating in the Dutch National Intensive Care Evaluation (NICE). Outcome measures were ICU mortality and hospital mortality, length of hospital and ICU admission, and standardised mortality ratio (SMR). RESULTS: Data from 55,016 admissions were registered. The median APACHE II score was 15 (P25-P75: 10-20) and the median SAPS II score was 29 (19-43). The median ICU length of admission for individual ICUs varied between 0.86 and 2.76 days. The occupied ICU capacity of individual ICUs varied between 220 and 1260 days per 100 patients admitted for non-cardiosurgical patients and between 110 and 330 days per 100 patients admitted for cardiosurgical patients. The ICU mortality and hospital mortality were 9.0% and 12.9% respectively. The mean SMR according to APACHE II was 0.95 (95% CI: 0.93-0.98). The SMR of the individual participating hospitals varied between 0.55 (95% CI: 0.37-0.80) and 1.20 (1.13-1.28). CONCLUSION: Hospital mortality for ICU-admitted patients in the NICE registration was 12.9%. For patients who could be evaluated with the APACHE II model, actual hospital mortality was lower than predicted by this model. Significant differences in length of admission, hospital mortality and SMR were found between individual hospitals.

APACHE↗
PubMed2003

[Intensive care medicine in the Netherlands, 1997-2001. II. Changes over time and differences between hospitals].

OBJECTIVE: To describe efficacy (mortality) and efficiency (length of admission) of intensive care (IC) treatment after admission due to a prior cardiothoracic operation or pneumonia, based on data from the Dutch National Intensive Care Evaluation (NICE) foundation. DESIGN: Descriptive. METHOD: Data for the period 1 January 1997-31 December 2001 were extracted from the NICE databank for patients admitted after cardiothoracic surgery and for patients admitted with pneumonia. The variables changes in time, risk factors for mortality, and differences between hospitals were analysed. RESULTS: There were 25,463 admissions to 5 hospitals following cardiothoracic surgery and 1408 admissions to 18 hospitals due to pneumonia. An increase in valve surgery was noted in the cardiothoracic surgery group: from about 10% to about 25%. In the group undergoing valve operations, there was an increase in the average age of the patients and in the number of patients with comorbidity. No significant differences in mortality between hospitals were detected. However, the length of ICU treatment differed. Hospital mortality in the pneumonia group was 33.9%. Differences between hospitals with respect to mortality (both crude mortality and severity-of-illness adjusted mortality) and length of ICU admission were found. CONCLUSION: With the NICE registration it is possible to detect differences and trends. This is a valuable tool for indicating where and how quality and efficiency in intensive care medicine can be improved.

Cardiac Surgical Procedures↗
PubMed2000

The added value that increasing levels of diagnostic information provide in prognostic models to estimate hospital mortality for adult intensive care patients.

OBJECTIVE: To investigate in a systematic, reproducible way the potential of adding increasing levels of diagnostic information to prognostic models for estimating hospital mortality. DESIGN: Prospective cohort study. SETTING: Thirty UK intensive care units (ICUs) participating in the ICNARC Case Mix Programme. PATIENTS: Eight thousand fifty-seven admissions to UK ICUs. MEASUREMENTS AND RESULTS: Logistic regression analysis incorporating APACHE II score, admission type and increasing levels of diagnostic information was used to develop models to estimate hospital mortality for intensive care patients. The 53 UK APACHE II diagnostic categories were substituted with data from a hierarchical, five-tiered (type of condition required surgery or not, body system, anatomical site, physiological/pathological process, condition) coding method, the ICNARC Coding Method. The inter-rater reliability using the ICNARC Coding Method to code reasons for admission was good (kappa = 0.70). All new models had good discrimination (AUC = 0.79-0.81) and similar or better calibration compared with the UK APACHE II model (Hosmer-Lemeshow goodness-of-fit H = 18.03 to H = 26.77 for new models versus H = 63.51 for UK APACHE II model). CONCLUSION: The UK APACHE II model can be simplified by extending the admission type and substituting the 53 UK APACHE II diagnostic categories with nine body systems, without losing discriminative power or calibration.

APACHE↗
PubMed2000

Understanding terminological systems. I: Terminology and typology.

Terminological systems are an important research issue within the field of medical informatics. For precise understanding of existing terminological systems a referential framework is needed that provides a uniform terminology and typology of terminological systems themselves. In this article a uniform terminology is described by putting relevant fundamental notions and definitions used by standard organizations such as CEN and ISO into perspective, and interrelating them to arrive at a useful typology of terminological systems. This typology is illustrated by applying it to five well-known existing terminological systems.

Humans↗
PubMed2000

Understanding terminological systems. II: Experience with conceptual and formal representation of structure.

This article describes the application of two popular conceptual and formal representation formalisms, as part of a framework for understanding terminological systems. A precise understanding of the structure of a terminological system is essential to assess existing terminological systems, to recognize patterns in various systems and to build new terminological systems. Our experience with the application of this framework to five well-known terminological systems is described.

Humans↗
PubMed2000

Evaluation of DICE, a terminological system for intensive care.

Evaluative research and the introduction of the Patient Data Management System to support care have increased the need for structured and standardized registration of diagnostic information in Dutch intensive cares (IC). To this end a terminological system to describe diagnoses is needed. A terminological system is a system that denotes terms to concepts in a domain based on specifications of these concepts. During the last two years we have developed DICE (Diagnoses for Intensive Care Evaluation), a terminological system application which includes knowledge about the IC diagnoses domain, such as the anatomical localization, the pathophysiology and the etiology. This paper briefly describes the design of DICE and focus on the preliminary evaluation of DICE. DICE was evaluated on the basis of 126 diagnoses collected. The knowledge modeller as well as the intensivists judged DICE positively. However, there were some points for improvement. The knowledge modeller observed a problem in modelling dependencies between qualifiers of a concept and the intensivists observed some gaps in the knowledge base and were critical about the current interface to compose plural operative procedures.

Critical Care↗
PubMed1999

Analysis and design of an ontology for intensive care diagnoses.

Information about the patient's health status and about medical problems in general, play an important role in stratifying a patient population for quality assurance of intensive care. A terminological system which supports both the description of health problems for daily care practice and the aggregation of diagnostic information for evaluative research, is desirable for description of the patient population. This study describes the engineering of an ontology that facilitates a terminological system for intensive care diagnoses. We analyzed the criteria for such an ontology and evaluated existing terminological systems according to these criteria. The analysis shows that none of the existing terminological systems completely satisfies all our criteria. We describe choices regarding design, content and representation of a new ontology on which an adequate terminological system is based. The proposed ontology is characterized by the explicit and formal representation of the domain model, the metaspecification of its concepts, the vocabulary to define concepts and the nomenclature to support the composition of new concepts.

Diagnosis, Computer-Assisted↗
PubMed1998

An evaluation of Patient Data Management Systems in Dutch intensive care.

OBJECTIVE: To assess the agreement between the functions of seven configurations of Patient Data Management Systems (PDMS) and the Dutch specifications prepared by the users prior to use. DESIGN: An observational descriptive study with hospital visits of seven configurations of five different PDMS systems including three commercial systems and two locally developed systems. SETTING: Seven Dutch level I intensive care units in university and teaching hospitals. MEASUREMENTS AND RESULTS: A substantial disagreement was found between the Dutch specifications and the actual functions of the PDMS configurations tested. Between the PDMS configurations, major differences in key features, including "automated charting", "information and care planning", and "management information", were observed. Automated charting is adequately supported by the three commercial systems. All configurations tested had limited functions supporting care planning. In none of the configurations tested was the required function present to support unit management with reports on resource utilisation and outcome performance. The automatic calculation of prognostic scores was either absent or incorrect. The implementation, the (continuous) configuration and the training required a substantial investment in costs and human resources. CONCLUSION: Today, none of the PDMSs tested satisfy the Dutch specifications. This can be explained by technical impossibilities of the systems and shortcomings in the actual configuration or in the unit organisation. The PDMS might become a valuable tool in improving the quality of ICU practice, but full implementation of these systems according to the specifications still has a long way to go.

Database Management Systems↗
PubMed1998

The relation between TISS and real paediatric ICU costs: a case study with generalizable methodology.

OBJECTIVE: To determine the quantitative relation between the Therapeutic Intervention Scoring System (TISS) in combination with other relevant clinical variables and the real costs of (paediatric) intensive care. DESIGN: A prospective, observational study. SETTING: A Ten-bed paediatric intensive care unit in a university children's hospital. PATIENTS AND PARTICIPANTS: In a 17-months registration period we collected patient- and treatment-related data for all 611 consecutive admissions. A 21-day calibration period was used to collect detailed data to calculate the real costs of 33 consecutive admissions, in addition to the same data as in the registration period. MEASUREMENTS AND RESULTS: We used the Multi Moment Measurement method to measure time spent by nurses and physicians and medication used in the 21-day calibration period. The calibration period data set with explanatory variables including TISS was used to build a regression model to estimate nurse and physician time, which were converted to personnel costs, and to estimate medication costs. The regression models built from the calibration period were subsequently used to estimate the total costs per day and per admission in different patient groups in the registration period. CONCLUSION: It was feasible to calculate total direct medical costs based on a limited number of readily available clinical variables related to patient characteristics and treatment, of which TISS was the most important determinant. The proposed methods provide further tools for assessment of (paediatric) intensive care unit performance.

Direct Service Costs↗
PubMed1997

Health status prediction in critically ill children: a pilot study introducing Standardized Health Ratios.

Performance of intensive care is usually quantified by means of standardized mortality rates, where standardization is directed towards the severity of illness on admission. However, as more critically ill patients survive, functional outcome and quality of life of these patients becomes more important. In a prospective study in a 10-bed tertiary paediatric intensive care unit (ICU), admission and follow-up health status were collected for 209 surviving patients. For this cohort of patients, health status 1 year after admission was also predicted, using the quantified health-utility-index (HUI), as a value between 0 and 1. For this purpose, two alternative multiple regression models were constructed. The most important predictors of 1-year health status were the level of sensation, mobility and cognition on admission to which self-care, systolic blood pressure, oxygen, Glascow Coma Scale, glucose and age may be added. The two alternative predictive models performed equally well (R2 = 0.83 and 0.84 respectively), indicating that health status could be predicted to a significant degree. The concept of relating expected future health status (based on base-line health status), with actual (observed) health status is denoted with the Standardized Health Ratio (SHR). In combination with the Standardized Mortality Ratios (SMR), such a ratio may become a new comprehensive indicator of performance in intensive care medicine.

Adolescent↗