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PubMed2004

Information theory for evaluating environmental classification systems.

Environmental pollution data are often ranked in rule-based classification systems. These environmental data are separated in predetermined classes of a classification system for a better and smarter characterization of the state of pollution. Often the measured values are transformed, e.g. in pseudocolor maps, and can then be presented in maps. For some environmental compartments different classification systems for evaluating environmental loadings are used. Because of the dissimilarity of the various classification systems direct visual comparison is difficult. However, by means of information theory an objective comparison of these various classification systems based on their information content enables a decision to be made about which system is the most informative for objective assessment of the state of pollution. By means of the new measure "multiple medium information content" (multiple entropy) objective and simultaneous comparison of all channels (in an environmental classification system: pollutants) of each classification system is now possible. Furthermore the development of the state of pollution over the whole investigation period can be detected by means of information theory. On the basis of the conditions of the established rule-based systems the use of information theory enables definition of new ranges of classes in order to reach the optimum of information during conversion into the environmental classification system.

Journal Article↗

PubMed2000

[The new WHO classification of malignant lymphoma. After "REAL" a further step on the road to a worldwide consensus].

For decades, rival classification systems for malignant lymphoma that were hardly even comparable have existed side by side: the Kiel Classification has so far been used in the German-speaking parts of Europe and the "Working Formulation" mainly in the USA. At the beginning of the 1990's it became possible to overcome this unsatisfactory situation, when pathologists in the Old and New Worlds joined forces to elaborate a new classification for lymphoma, the Revised European-American Lymphoma (REAL) Classification, based on current scientific data. One new feature is the absence of a malignancy grading that is applicable to more than one entity. The system centres on the definition of distinct lymphomatous diseases that can be diagnosed with a high degree of reproducibility. Morphological and clinical characteristics are used for diagnosis, but so, consistently, are immuno-phenotypical and molecular genetic ones. An international cooperative study has confirmed the high reproducibility and clinical practicability of this tentative classification system. An international panel of pathologists appointed by the World Health Organization has updated the REAL classification, which is expected to be published in the updated version in 2001 under the title New WHO Classification. The articles that follow are based on the new WHO classification.

Europe↗

PubMed2004

Carcinoma of the cardia: classification as esophageal or gastric cancer?

INTRODUCTION: The cardia is the anatomical borderland between the esophagus and stomach. Carcinomas of the cardia are regarded to share features of both, esophageal and gastric cancers. Controversy exists concerning their appropriate classification and whether these tumors comprise--in respect to tumor biology, pathophysiology as well as clinical features--an entirely separate entity. CLASSIFICATION: In order to distinguish cardia carcinomas from other adenocarcinomas arising within the vicinity of the esophagogastric junction, a classification system has been introduced from a surgical viewpoint, and is now well established and increasingly used worldwide. According to the topography of the main tumor mass, cardia carcinomas (AEG II) are distinguished from adenocarcinomas of the distal esophagus (AEG I) and subcardiac gastric cancers (AEG III). The tumor-node-metastasis (TNM) staging system by the International Union Against Cancer (UICC) does not provide a separate classification for tumors of the esophagogastric junction. The use of the classification for esophageal or for gastric cancers is recommended, irrespective of the elementary differences in the classification of lymphatic spread implemented herein. DISCUSSION: New aspects concerning this controversial debate are discussed based on current insights into the pathogenesis and the cellular origin of these entities. The controversies concerning the classification of cardia carcinomas and the failure of the current esophageal and gastric cancer staging systems to reflect the peculiarities of this entity accurately, present a strong argument in favor of a new classification system.

Adenocarcinoma↗

PubMed2004

[The Barthel Index in geriatrics. A context analysis for the Hamburg Classification Manual].

The Barthel Index (BI) is firmly established as an assessment instrument in geriatrics. It is a proven, clear and easy-to-use instrument for the recording of basic daily functions. However it is increasingly finding new applications beyond its original, clinically orientated use. It has been applied as a quality parameter, as an instrument for the management of service delivery provision and as an instrument to record treatment efforts relevant to care or costs. This study considers the basic suitability prerequisites of the Barthel Index for these applications.With the Hamburg Classification Manual for the BI, German geriatrics has made a contribution to the standardized operationalization of the items and to the standardized evaluation of aids. An evaluation was performed on a total of 5262 Barthel classifications at seven geriatric hospitals according to existing classification practice by comparison with 5483 classifications after introduction of the Hamburg Classification Manual. No significant differences were found in Barthel Index total scores either on admission or on discharge. With respect to further applications it is essential to be aware that the usability of the total score (including its changes over the course of time) is limited because of the ordinal scaling of the BI. Studies have been carried out which show how important this is, although they have so far received little attention. As a grading criterion the BI takes account not only of the "functional status" but also of the "extent of support effort". This can lead to positive changes in one focus -- especially with the use of aids -- without associated improvements in the other focus. Whether the BI in this form is meaningful for a specific application must be tested separately for each individual context. There is no justification for assuming that the BI has general validity irrespective of application. The results of a systematic literature survey on the testing quality criteria of the BI indicate an astonishingly generous approach to the question of the validity of the BI. Contrary to widespread opinion, cognitive-psychological components do influence the classification result of the BI. As an addition to the Hamburg Classification Manual we recommend that the extent of this influencing factor should also be more clearly operationalized and that "stimulation required" for the carrying out of an activity be included in the evaluation equivalent to the factor "supervision required" already introduced by Barthel and Mahoney. The BI has shown itself to be an efficient but nonetheless multidimensional global parameter in clinical practice, whose meaningfulness is on the level of the individual item and whose validity, particularly as total score and course parameter, needs to be proven for each new application. The Hamburg Classification Manual, as a standardized and consensus-based operationalization of the BI, provides an important basis for this.

Activities of Daily Living↗

PubMed2004

[The new IHS classification. Background and structure].

The diagnosis of headache is nowadays based on the classification criteria of the International Headache Society (IHS). This classification can be seen in a historical context with a very first version published by an ad-hoc-committee of the National Institute of Neurological Diseases and Blindness in the USA. In 1988 the first IHS version appeared, and this was revised in its current version in 2003. The classification is divided into primary (i.e., idiopathic) and secondary (i.e., symptomatic) headache and into cranial neuralgias and facial pain. The classification is based on the description of the headache features and thus a phenomenological rather than an etiological classification. Furthermore, not the patient as a subject but the headache as a clinical entity is classified. Therefore, some patients can have more than one headache diagnosis. In total, 14 different headache groups and more than 170 headache types are separated. The changes compared to the last classification (such as introduction of chronic migraine and of several new rare idiopathic headache disorders) and the perspectives for future classifications (e.g., problems of genetic classification) are discussed.

Headache↗

PubMed2002

Classification of thoracic and lumbar spine fractures: problems of reproducibility. A study of 53 patients using CT and MRI.

Reproducibility of fracture classification systems in general has been a matter of controversy. The reproducibility of spinal fracture classifications has not been sufficiently studied. We studied the inter-observer and intra-observer reproducibility of the Magerl (AO) classification using radiograms, CTs and MRIs of 53 patients. We compared this classification with the older and simpler Denis classification. Five observers classified the fractures, first using the radiograms and CTs and, 6 weeks later, with radiograms and MRIs. Three of the observers repeated the readings after 3 months. Three observers also classified the fractures according to Denis. Agreement was measured using Cohen's kappa test. The type (A, B, C) classification of the AO system was fairly reproducible with CTs. With MRI this was only moderate. Group subclassification of the types yielded higher kappa values, corresponding to substantial agreement. The agreement was, in general, better with the Denis classification, but the variance was higher due to the difficulty of finding proper categories for some injury patterns. Although the AO classification allows proper registration of all kinds of injury, the reproducibility, especially at the type level, is problematic. Use of MRI and better definition of the distinctive properties of the three different types may enhance the reproducibility of the scheme.

Diagnosis, Differential↗

PubMed2006

Inter-examiner reliability in the assessment of low back pain (LBP) using the Kirkaldy-Willis classification (KWC).

Reliable classification systems and clinical tests are sought for the care of patients with low back pain (LBP). The objectives of this clinical study were to evaluate inter-examiner reliability in the classification of patients with LBP, the influence of radiological findings on the classification and the reliability of some clinical tests. Two examiners independently assessed 50 outpatients with LBP. Inter-examiner reliability in classification of patients with LBP using Kirkkaldy-Willis classification (KWC) system and in 30 clinical tests was calculated as percentage agreement and kappa coefficients (kappa). Inter-examiner reliability was excellent (kappa>0.8) for classification according to KWC. Radiological findings did not influence the reliability. Age of the patient, movement range, and pain and neurological signs seemed to guide the decision on classification. The reliability of clinical tests was good (kappa>0.6) in 6 tests and moderate (kappa>0.4) in 12 tests. Good inter-examiner reliability was found for the SLR test, movement range and sensibility testing with spurs in dermatome areas. We conclude that the KWC for classifying patients with LBP seems to be a reliable classification system depending on a few key observations and that moderate and good inter-examiner reliability can be achieved in several clinical tests in the assessment of LBP.

Adolescent↗

PubMed2005

Movement disorders: classifications.

Movement disorders (ataxia, dystonic disorders, gait disorders, Huntington disease, myoclonus, parkinsonism, spasticity, tardive dyskinesia, tics and tremor) are clinically, pathologically and genetically heterogeneous and are characterized by impairment of the planning, control or execution of movement. Current classifications of these disorders have inherent shortcomings due to the complex nature of movement disorders and the lack of diagnostic tests for the majority. Undiscriminating terminology, as well as the clinical, pathological and genetic heterogeneity, further complicate the development of comprehensive categorizations. Modern classification schemes tend to focus on clinical, pathological or genetic/molecular criteria, but more recent attempts have been made to integrate across these levels. From a historical perspective, two 'golden ages' have shaped the current and evolving classification schemes: (1) the definition of clinical pathological entities in the early twentieth century and (2) the application of molecular neurogenetics in the past 10-15 years. However, the classification of movement disorders on clinical grounds (according to age at onset, distribution of symptoms, disease course, provoking factors and therapeutic response) remains one of the most useful modes of categorization. Postmortem criteria have been employed to distinguish between degenerative and nondegenerative disorders, and specific hallmarks may be required to establish or confirm a diagnosis. Genetic features used for classification purposes include mode of inheritance and molecular genetic data, such as linkage to a known gene locus or identification of a specific genetic defect. A final classification scheme is based on alterations in molecular mechanisms (e.g. trinucleotide expansions) or protein function (e.g. channelopathies). Despite recent advances, it may not be possible to develop the 'ultimate' classification of movement disorders, and different patterns of lumping and splitting may be useful for the clinician, the pathologist or the geneticist/molecular biologist. Furthermore, certain individual cases with unique features may not fit into any particular category. Continued research by both clinicians and basic scientists is necessary in order to refine and redefine classification schemes of movement disorders.

Dystonia↗

PubMed1989

Complications of uterine cervix carcinoma treatments: the problem of a uniform classification.

Ninety-six articles published in English, French and Italian between 1938 and 1986 have been examined in order to analyze the classifications and reporting methods used by different researchers. Specialty and nationality of authors, classifications used, organs, systems and anatomic sites considered, weight given to the most frequently encountered complications are studied. Fifty-nine papers make no use of classification of complications of any kind, neither by onset time, nor by severity, but simply describe the observed events. The remaining 37 papers use a classification based on varying criteria. Thirty-four authors use a classification by severity according to different criteria; four authors classify complications according to the treatment required. In the remaining 30 papers a true scale is used. A total of 22 classifications emerges from these papers; in eight cases a previously published classification is used. The weight assigned by different authors to specific complications has been compared. The following main points emerge from the analysis: about two authors out of three simply describe the observed complications; 30 rely on a true scale of severity, but 22 different grading systems are used. Most classifications do not cover all possible complications, both surgical and radiotherapeutic, but concentrate on those complications which are typically generated by author's therapeutic approach. Only three take into account complications related to different treatment modalities. The observation period is not standardized: published data derive from follow-up times spanning from some months to many years. Authors mainly focus their interest on gastrointestinal and/or urinary complications; other organs and systems are rarely considered.(ABSTRACT TRUNCATED AT 250 WORDS)

Antineoplastic Agents↗

PubMed1990

Histological classification of the non-Hodgkin's lymphoma.

The non-Hodgkin's lymphomas (NHL) are a diverse group of neoplasms which show subtle histological differences. This has led to difficulties in formulating reproducible classifications of NHL that are both histologically and clinically relevant. In this review we discuss some of the historical aspects of NHL classification leading up to the principal classifications in current use. In comparing these we put forward reasons why we regard the updated Kiel classification as that which is the most soundly based in clinical, histological and biological terms. The Kiel classification, unlike its competitors, lends itself to further updating as new clinicopathological entities become established, without loss of its essentially sound foundations. Thus the classification of T-cell lymphomas can only be regarded as provisional and certain extranodal lymphomas, which are clear clinicopathological entities, await classification. The biological foundation of the Kiel classification should allow further updating to incorporate these entities and the tighter definitions of categories of NHL that will surely result from the application of cytogenetics, molecular biology and studies of lymphocyte homing mechanisms.

B-Lymphocytes↗

PubMed1987

Classification of dangerous substances and pesticides in the European economic community directives: a proposed revision of criteria for inhalation toxicity.

Criteria for the classification of dangerous substances with respect to their inhalation toxicity were originally proposed by the European Economic Community (EEC) on the basis of a 1-hr LC50, as were the similar United Nations (UN) "transport" criteria. Both sets of criteria have since been amended for a 4-hr LC50, but whereas the UN criteria limits have been decreased to compensate for the increased exposure time, the EEC limits have not. This has introduced an anomaly into the EEC classification scheme whereby substances are classified more severely than they were previously. The EEC scheme is now out of line with the UN criteria and other international guidelines and gives a much more stringent toxicity classification for individual substances by inhalation than by the oral route, as well as causing an unjustifiable duplication of animal tests. This anomaly has led to a proposal by the Federal Republic of Germany for revised criteria. This paper examines the scientific basis for the relationship between inhalation exposure duration and toxicity, and for a comparison of the LD50 and LC50 classifications for individual substances. It is concluded that the proposed German revised classification scheme is more in line with the UN transport criteria and international guidelines and provides a rational basis for a classification scheme for inhalation toxicity. The classification criteria therefore should be harmonized by a revision of the EEC classification limits for inhalation toxicity.

Aerosols↗

PubMed2005

Reliability of classification systems for intertrochanteric fractures of the proximal femur in experienced orthopaedic surgeons.

INTRODUCTION: The aim of this study was to determine the reliability of currently used classification systems for intertrochanteric fractures of the proximal femur, and to determine the reliability of these systems in experienced orthopaedic surgeons. MATERIALS AND METHODS: Forty intertrochanteric fractures of the proximal femur were classified independently by five experienced observers using the AO, Evans, Kyle, and Boyd classification systems on two separate occasions 3 months apart. The interobserver and intraobserver variation was assessed using kappa statistics. RESULTS: The level of agreement for classification into AO groups was almost perfect or substantial, and higher than other classification systems. When the fractures were further classified using the AO classification with subgroups, reliability became worse. CONCLUSIONS: The current study suggests that the AO classification system with groups can be used more reliably to measure intertrochanteric fractures of the proximal femur than Evans, Kyle, and Boyd classification systems. However, the reliability of the AO classification with subgroups is not satisfactory.

Femur Head↗

PubMed2004

Comparison of Mayo Clinic risk score and American College of Cardiology/American Heart Association lesion classification in the prediction of adverse cardiovascular outcome following percutaneous coronary interventions.

OBJECTIVES: We compared American College of Cardiology/American Heart Association (ACC/AHA) lesion classification with the recently proposed Mayo Clinic risk score to predict complications following percutaneous coronary intervention (PCI). BACKGROUND: The ability of the ACC/AHA classification system to predict complications following PCI has been modest. With the inclusion of patient demographics, acuity of presentation, and measure of left ventricular function, models with better discriminatory accuracy are presently available. METHODS: The Mayo Clinic risk score is constructed by adding integer scores for the presence of eight variables. We mapped the lesion-specific risk levels to a patient level by counting the number of lesions in each class (A, B1, B2, C, and unknown). RESULTS: In 5,064 PCIs, 183 patients (4%) had the primary end point (death, Q-wave myocardial infarction, stroke, emergency coronary artery bypass graft). Of the 7,632 treated lesions, 891 (12%) were unsuccessfully treated with PCI (residual stenosis >20%). The discriminatory ability of the Mayo Clinic risk score model for prediction of the primary end point, as measured by the c-statistic, was 0.78 (95% confidence interval [CI] 0.74 to 0.81). The Mayo Clinic risk score offered significantly better risk stratification than the ACC/AHA lesion classification counts (95% CI for c-statistic difference: 0.05 to 0.15). Regarding angiographic success, the ACC/AHA lesion classification was a better system (95% CI for c-statistic difference: -0.08 to -0.03 favoring ACC/AHA classification), although its absolute ability was modest (c = 0.58). CONCLUSIONS: Mayo Clinic risk score offers significantly better prediction for cardiovascular complications than the ACC/AHA classification. However, lesion classification by ACC/AHA classification is a better predictor for angiographic success.

Aged↗

PubMed2004

A pilot study on the application of statistical classification procedures to molecular epidemiological data.

The development of new statistical methods for use in molecular epidemiology comprises the building and application of appropriate classification rules. The aim of this study was to assess various classification methods that can potentially handle genetic interactions. A data set comprising genotypes at 25 single nucleotide polymorphic (SNP) loci from 518 breast cancer cases and 586 age-matched population-based controls from the GENICA study was used to built a classification rule with the discrimination methods SVM (support vector machine), CART (classification and regression tree), Bagging, Random Forest, LogitBoost and k nearest neighbours (kNN). A blind pilot analysis of the genotypic data set was a first approach to obtain an impression of the statistical structure of the data. Furthermore, this analysis was performed to explore classification methods that may be applied to molecular-epidemiological evaluation. The results showed that all blindly applied classification methods had a slightly smaller misclassification rate than a random classification. The findings, nevertheless, suggest that SNP data might be useful for the classification of individuals into categories of high or low risk of diseases.

Breast Neoplasms↗

PubMed2006

Development of a MSW classification system for the evaluation of mechanical properties.

To date, sparse information is available on the mechanical properties of municipal solid waste and the results of published work are often hard to compare due to differences in waste composition and therefore properties. To allow comparison, a unified classification system for waste is deemed crucial. Existing classification systems are presented and discussed. For a geotechnical classification, mechanical properties, size, shape and degradability potential of waste components have to be taken into account. A new and improved classification system for waste components is proposed, which complies with the requirements of a geotechnical classification system. It classifies waste components based on: (1) their material engineering properties (e.g., shear, compressive and tensile strength), (2) a size distribution of the components, (3) the component shape (reinforcing, compressible and incompressible), and (4) the degree of degradability. The proposed classification system is applied to data from the literature and methods for presenting classification information are demonstrated. Further work required to develop a full classification system for waste bodies is highlighted.

Mechanics↗

PubMed2003

International classification of ultrasound images in cystic echinococcosis for application in clinical and field epidemiological settings.

The increased knowledge of the natural history of cystic echinococcosis (CE) by the recent expansion in the use of ultrasound (US) in field and clinical studies has necessitated the development of a new WHO standardised classification of US images. Use of such a classification will enable clinicians to examine recommended clinical procedures for the different cyst types. It will also allow scientists to compare data on the occurrence of cyst types in different parts of the world providing evidence to examine strain differences in the causative organism Echinococcus granulosus. The classification proposed follows that of the first classification developed by Gharbi et al. [Radiology 139 (1981) 459] which has been widely used, but in modified forms, since its publication. The classification presented here is intended for use in field epidemiological studies as well as for clinical investigators. The classification is intended to follow the natural history of CE and starts with undifferentiated simple cysts, as presumably hydatid cysts evolve from these structures. These simple cysts, however, may be due to a number of different aetiologies (parasitic lesions, congenital disorders, biliary cysts or neoplasms) and, therefore, require further diagnostic tests to reveal their identity. As their origin is uncertain they are not given the designation of a CE type lesion, and, in the proposed classification, should be recorded as cystic lesions (CL). The first clinical group starts with cyst types CE 1 and 2 and such cysts are active, usually fertile cysts containing viable protoscoleces. CE Type 3 are cysts entering a transitional stage where the integrity of the cyst has been compromised either by the host or by chemotherapy and this transitional stage is assigned to the second clinical group. The third clinical group comprises CE Types 4 and 5 which are inactive cysts which have normally lost their fertility and are degenerative. The use of the standardised US classification will facilitate the application of uniform standards and principles of treatment currently recommended for each cyst type.

Animals↗

PubMed2003

Evaluation of the American College of Cardiology/American Heart Association and the Society for Coronary Angiography and Interventions lesion classification system in the current "stent era" of coronary interventions (from the ACC-National Cardiovascular Data Registry).

In 1988 American College of Cardiology (ACC)/American Heart Association (AHA) Guidelines for Coronary Angioplasty proposed a lesion classification system to stratify lesions by difficulty and risk to better understand the outcomes of coronary interventions. It was a 3-level (A, B, and C) classification based on 11 lesion characteristics. A modification, dividing the intermediate B category into B1 and B2, is also in common use. Recently, a simplification of this classification was evaluated using the large Society for Cardiac Angiography and Interventions (SCAI) Registry (SCAI I = non-C/patent; SCAI II = C/patent; SCAI III = non-C/occluded; SCAI IV = C/occluded). The lesion classification systems were evaluated in 61,926 patients from the ACC National Cardiovascular Data Registry who underwent single-vessel percutaneous coronary intervention between January 1998 and September 2000. Stents were placed in 74.5% of patients. Logistic models for lesion success and complications were constructed and compared. The c statistic for success using the ACC/AHA original classification system was 0.69, 0.71 for the modified ACC/AHA system, and 0.75 for the SCAI classification. The range of complication and success rates was greater using the SCAI models, and the logistic models for success and complication were more robust for the SCAI system. Thus, in the large ACC-National Cardiovascular Data Registry, with a high percentage of stent usage, the simpler SCAI lesion classification provided better discrimination for success and complications than the more complex ACC/AHA lesion classification system-original or modified.

Angioplasty, Balloon, Coronary↗

PubMed2001

The classification of lymphomas and leukemias.

Classifications of lymphomas and leukemias have developed from two distinct clinical needs - to understand the natural history of these diseases in order to predict outcome and to make treatment decisions in a rational fashion. The utility of classifications for research on etiology of these diseases has not guided their development in the past. The classification of leukemias and lymphomas has undergone dramatic changes with increasing understanding of the development of the normal immune cells. Historically, the first entity to be recognised was Hodgkin disease. Other malignancies of the lymphatic system were then called 'Non-Hodgkin Lymphomas' (NHL), a distinction that remains valid even today. Cancers that tend not to form distinct masses but usually present with a raised white blood cell count were called leukemias. As knowledge has improved, however, the early juxtaposition of leukemias versus lymphomas has lost relevance, since often the same entity can present in either way. With better understanding the terms 'lymphosarcoma' and 'reticulosarcoma', which were earlier widely applied have been replaced by more precise terminology. Different classifications have been put forward over the years. The 'Revised European and American Classification of Lymphoid Neoplasms' and the derived WHO classification are structured to mirror normal B/T-cell differentiation. In these modern classifications, distinct disease entities are defined based on the combination of morphology, immunological and molecular techniques and clinical features. The proposed major groups of lymphoid neoplasms are B-cell lymphomas/leukemias, T/Natural Killer-cell lymphomas/leukemias and Hodgkin disease. About 20 entities are recognised. This provides for the first time a truly international view of lymphomas and leukemias. It has emerged that such a classification can be used successfully by expert hematopathologists and yields highly reproducible results. It is also clear that no single marker, be it morphology, genetic analysis or immunophenotyping can be used as the 'gold standard' for diagnosis but that a combination of techniques is needed.

Hodgkin Disease↗