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PubMed2002

The new World Health Organization classification of haematopoietic and lymphoid tumours: a dermatopathological perspective.

The World Health Organization (WHO) has published a new consensus classification of tumours of haematopoietic and lymphoid tissue, based on recognizable disease entities defined by clinical and scientific criteria. The WHO does not support the use of stand-alone organ-related classifications, such as for skin. The Royal College of Pathologists (London) has adopted the WHO classification in its minimum dataset for the histopathological reporting of lymphoma and this will be used in the National Health Service Skin Cancer Dataset. The purpose of this review is to highlight the principal primary and secondary cutaneous haematopoietic and lymphoid tumours that are defined in the WHO classification. The review also discusses selected problematical areas in the WHO classification relevant to the skin and contains suggestions to encourage a unified approach in the use of the WHO coded summary. These represent an attempt to facilitate future progress and research in the field of cutaneous lymphoma. They are perceived as possible building-blocks for wider discussion and not as alterations to the classification. The WHO classification has been compared with a road map that indicates directions for future clinical and scientific research.

Hematologic Neoplasms↗

PubMed2000

Cytokeratin profiles of the thymus and thymomas: histogenetic correlations and proposal for a histological classification of thymomas.

AIMS: Since cytokeratins (CKs) are useful as differentiation markers for histogenetic and classification studies, we investigated the CK profiles of the thymus and thymomas in an attempt to understand the histogenetic correlation and to propose a histological classification. METHODS AND RESULTS: Nine thymuses and 34 thymomas were immunostained for various CKs of different molecular weights and involucrin. Based on cytomorphology and histoarchitecture, thymomas were classified into spindle cell (SC), small polygonal cell (SPC), mixed, organoid, large polygonal cell (LPC) and squamoid (SQ) thymomas for compiling CK profiles. The thymus was shown to comprise four epithelial compartments, each expressing a different CK profile. Different histological types of thymoma expressed different CK profiles. By correlating the CK profiles of the thymus and thymoma, SPC, SC and LPC thymomas appeared to be related to subcapsular, medullary and cortical cells, respectively. Organoid thymoma recapitulated the structure and CK profile of the normal thymus, while SQ thymoma acquired additional squamous type CK. The applicability and usefulness of the proposed histological classification were evaluated on 147 thymomas by correlating the results with their invasive behaviour. One hundred and thirty-nine cases (95%) could be classified and different histological types correlated strongly with their invasive behaviour. CONCLUSIONS: The thymus is a complex epithelial organ composed of heterogeneous cell types giving rise to various related histological types of thymoma. The results of the CK profile study supports the proposed histological classification, which is pathologically applicable and clinically useful in correlating with invasiveness. This cytomorphological classification, supported by the CK expression patterns, is comparable to Müller-Hermelink classification and the new WHO histological classification except that a separate group of SPC thymoma expressing only CK14 and CK19 was identified and separated from mixed thymoma.

Biomarkers, Tumor↗

PubMed1998

A comparison between patients' experiences of how their caring needs have been met and the nurses' patient classification--an explorative study.

AIM: To examine whether patient classification carried out in accordance with the Oulu Patient Classification (OPC) method can measure the patient's caring needs in a reliable manner as seen from the patient's perspective. BACKGROUND: On the basis of earlier research it can be established that there are differences between nurses' and patients' assessments of patients' caring needs. Research on patients' assessments of perceived caring needs and the care they receive in connection with patient classification does not seem to have interested researchers in caring science. METHODS: The reliability from the patient's perspective is gauged by comparing the patient's perceived caring needs with the nurse's patient classification during a 24-h bed-day. Data was collected during a semi-structured interview with a total of 73 patients. Documentary analysis was carried out on the basis of patient classifications by 30 ward nurses. FINDINGS: On the basis of the degree of correspondence between nursing care intensity experienced by the patients and the nurses' patient classification it was decided whether the patients' caring needs had been met. The results indicate, however, that patient classification as a gauging method has a built-in reductive function regarding the patient's need for care and nursing care intensity. CONCLUSIONS: Nevertheless the OPC offers possibilities from a patient perspective of providing an overall picture of the patient's nursing care intensity and can therefore serve as a reliable basis for decisions concerning staff planning.

Diagnosis-Related Groups↗

PubMed1996

The International Headache Society classification of chronic daily and near-daily headaches: a critique of the criticism.

The classification of the International Headache Society (IHS) published in 1988 has been positively received throughout the world. However, the classification of headaches occurring daily or almost daily has been criticized repeatedly. This criticisim is discussed in the present review. It is possible to classify virtually all chronic headache patients using the IHS Classification and there seems to be more need for emphasizing a correct application of the classification than for a revision in this regard. The entity of transformed migraine is disputed and so is the existence of hemicrania continua. Neither of these syndromes has been adequately defined nor studied. Chronic daily headache of sudden onset (new persistent daily headache) is not adequately classified at present and should be included as a separate entity in the next edition of the IHS Classification. In a future revision it should also be possible to classify drug-related headache simply on the basis of drug consumption and without mandatory demands for withdrawal. Better longitudinal studies of patients with chronic daily headache are necessary to evaluate finally whether a revision of the classification of these headache syndromes is necessary. Eventually the ongoing discovery of migraine genes is likely to change radically the classification of migraine.

Chronic Disease↗

PubMedDate not supplied

Os calcis fractures: analysis of interobserver variability in using Sanders classification.

The os calcis is the most frequently fractured tarsal bone. In 1992 Sanders developed a classification system based on coronal and axial computed tomography (CT) scans of the calcaneus. This classification is the one used most frequently today in treatment decision making and reporting of results. The objective of this study was to assess the degree of interobserver variability in using this classification system. Thirty CTs of calcaneal fractures were chosen randomly from the past 5 years in 2 tertiary care centers. The CTs were reviewed by 3 orthopedic surgeons and one senior orthopedic resident who classified the fractures according to Sanders' classification. The results were first tabulated and analyzed by using a weighted kappa test including the subcategories. The weighted kappa value achieved was.56, with a 95% confidence interval of.45-.67. The subcategories of the classification were then further combined and a second weighted kappa test was performed to assess agreement between general classes. The weighted kappa value achieved was.48, with a 95% confidence interval of 0.37-0.59. We concluded that Sanders' classification system did prove to achieve moderate agreement among users, thus representing a useful classification system.

Calcaneus↗

PubMed1999

Proposal for modification of the TNM staging classification for cancer of the oral cavity. DOSAK.

AIM: The prognostic value of the TNM and pTNM classifications currently used for tumours of the oral cavity is unsatisfactory. A better classification should be aimed at as today's definition of T4 leads to overclassification of many tumours and today's definition of N3 results in too few lymph nodes in this group. Until 1987 the grade of fixation of lymph-nodes was part of the N-classification for oral cancer as it is currently used in the N-classification of breast cancer. METHODS: From 1987 to 1991 the DOSAK tumour registry has stored 1532 primary cases of cancer of the oral cavity from 23 hospitals. Crosstables were applied to outline the classification rule for clinical and histopathological T and N based on important factors (T: tumour diameter and thickness; N: lymph node diameter and grade of fixation; pT: histopathological tumour diameter and thickness; pN: number of lymph nodes involved by the tumour). A Cox model was calculated and combinations of similar prognostic estimates were summarized to the same clinical and histopathological T and N. It was aimed at separating categories and achieving equivalent clinical and histopathological T classifications and group frequencies. In a final step a clinical and histopathological stage grouping can be proposed. RESULTS: The gradation of the survival rates shows a marked separation between the T, N and stage categories. The distribution of T, N and stage categories was more uniform when applying the new classification.

Austria↗

PubMed2004

[Diagnosis and classification of calcaneal fractures in computed tomography].

PURPOSE: To compare image quality of single-slice spiral CT (SSCT) and multislice spiral CT (MSCT) in the diagnosis and classification of calcaneal fractures and to present a rapid and precise algorithm for the classification system of Stuermer. MATERIALS AND METHODS: In 102 patients with 124 calcaneal fractures, spiral CT was performed, in 82 cases as SSCT with a slice thickness (SD) of 3 mm, a table speed (TS) of 3 - 4 mm/rot and an increment of 1.5 mm. In 42 cases, patients were scanned using MSCT (SD of 1.25 mm, increment 0.8 mm). For these examinations, 2 different scan protocols were used, with a TS of 3.75 mm/rot in one group (n = 21) and a TS of 7.5 mm/rot in the other group (n = 21). The image quality of axial sections and reconstructed images was assessed on a scale from 1 to 5 (1 = very good; 5 = insufficient). The fractures were evaluated using a classification system according to Stuermer, which assigns three main groups (A/B/C) and three subtypes (1/2/3). RESULTS: MSCT had substantial advantages over SSCT with respect to scan time and image quality, especially for multiplanar reformatting (median 1.5 versus 4.0). TS showed no significant influence on the image quality. The standardized evaluation of the images enabled a classification of fractures within 5 minutes. All fractures could be assigned to the different types and subtypes. This classification system takes into account the severity of the fracture and the therapeutic approach. The most common type (90 of 124 fractures) were "joint depression" fractures (type C), which were treated by surgery in 92 %. Type A fractures were treated conservatively in 72 %. CONCLUSION: Spiral CT, especially MSCT, allows rapid diagnosis and precise classification of calcaneal fractures, achieved with high quality multiplanar reformatting. The presented classification in different fracture types and subtypes allows an adequate planning of therapy.

Adolescent↗

PubMed2005

[Comparison of spine injuries by means of CT and MRI according to the classification of Magerl].

PURPOSE: A feasibility study of the classification of spine injuries by CT and MRI data according to the classification of Magerl for spine injuries. MATERIAL AND METHODS: In 39 patients, 46 injured vertebrae were evaluated by means of CT and MRI. A single-slice helical CT (Somatom Plus S, Siemens, Erlangen, Germany) was used with a collimation and feed of 2 mm and 3 mm, respectively. Sagittal reformations were reconstructed from these data sets. MR imaging was performed with 1.5T and 1.0T machines (Magnetom Vision and Magnetom Impact, Siemens). Transverse and sagittal T1-w SE- images as well as sagittal T2-w TSE- and STIR-images were generated. Each fractured vertebra was independently categorized two times according to the classification of Magerl on the basis of CT- and MRI-images. The CT- and MRI-classifications were subsequently compared. RESULTS: Most fractures were classified as impaction fractures (A1) or burst fractures (A3). Only 5/46 injuries of vertebrae were not given the same classification by means of CT and MRI (r = 0.9). MRI showed more bony lesions than CT (n. s., p > 0.05) and was able to evaluate ruptures of the longitudinal ligaments in 5 patients. CONCLUSION: Classification of spine injuries according to the Magerl-classification showed a significant agreement between CT and MRI and therefore a comparable evaluation of stability. MRI was superior in delineating ligamental lesions.

Adolescent↗

PubMed2002

Endoscopic assessment of the "Z-line" (squamocolumnar junction) appearance: reproducibility of the ZAP classification among endoscopists.

BACKGROUND: The histologic presence of intestinal metaplasia in the esophagus is a prerequisite for the diagnosis of Barrett's esophagus. Thus, use of the term Barrett's esophagus to describe certain endoscopic features in the distal esophagus is inappropriate. There is no accepted classification system for the endoscopic description of the squamocolumnar mucosal junction, the so-called "Z-line." Furthermore, no clear definition of the normal Z-line exists. A classification of the Z-line appearance has been proposed: the ZAP classification. The aim of this study was to assess the reproducibility of this classification. METHODS: Ten physicians with varying endoscopy experience were presented with 15 endoscopic photographs of the Z-line and were asked to classify them according to the ZAP classification. A second assessment was conducted between 7 and 15 weeks after the first. RESULTS: The median kappa values were in the range of 0.72 to 0.90 with regard to intraobserver as well as interobserver reproducibility, irrespective of experience with upper endoscopy. CONCLUSIONS: The intraobserver and interobserver reproducibility of the ZAP classification is substantial and thus it is feasible to use this classification to characterize the appearance of the Z-line at endoscopy.

Barrett Esophagus↗

PubMed2004

How reliable are reliability studies of fracture classifications? A systematic review of their methodologies.

Two independent reviewers performed a search in MEDLINE and EMBASE for fracture classification reliability studies. Data were obtained on classifications, image modalities, fracture selection processes, sample sizes and their justification, type and number of raters, practical issues for the classification sessions, statistical methods, and results. A 10-item checklist was devised for quality assessment of methodologies. 44 studies assessing 32 fracture classification systems were included. We found a wide variation of methodologies. For instance, the median number of raters was 5 (2-36) and the median number of fractures was 50 (10-200). This selection was considered representative in 17/44 of the studies. The true distribution of classification categories was estimated in 9 studies. The kappa coefficient was mostly used (39/44) to quantify the raters' agreement. Methodological issues are discussed. Given limitations in the use and interpretation of kappa coefficients, investigators should consider alternative methods that focus upon the accuracy of the classification systems. The development and adoption of a systematic methodological approach to the development and validation of fracture classification systems is needed.

Fractures, Bone↗

PubMed2004

The World Health Organisation's terminology and classification: application to severe disability.

PURPOSE: The purpose of this article is to describe the international classification system proposed by the World Health Organisation for describing individuals with disability. Initially the 'International classification of impairment, disability and handicap' (ICIDH) was used. This has been replaced by the 'International classification of functioning, disability and health' (ICF). Both of these systems will be described and followed by a discussion of the advantages and disadvantages of using the WHOs classification framework. An application to the field of severe disability will be made throughout. METHOD: Providing a theoretical framework for classification of disability in accordance with the system proposed by the WHO. RESULTS: The ICF is a useful tool that contributes to uniformity of international terminology and standardization in the disability field. It is not a minority model, and focuses on strengths and skills. CONCLUSIONS: An international classification system such as the ICF offers a conceptual framework for information that is relevant to the long-term consequences of disability. Although any type of classification system has certain limitations, the advantages present within the ICF outweigh the limitations.

Persons with Disabilities↗

PubMedDate not supplied

The classification of spinal deformities.

Any methods of classification of scoliosis deformity devised should recognise different aetiological and pathological causes of the conditions and their likely impact on the natural history of the spinal curvature. Such classification should aim to aid clinicians in their approach to treatment. Furthermore, any such system must have a high reliability and validity. Several approaches have been reported. Pathological classifications have been devised which relate to the system or tissue affected by the underlying pathology, such as congenital anomalies which affect the skeletal elements of the spine, general neurological problems or muscular disorders. Classification by age of onset has also been adopted, using criteria such as infancy or adolescence. However, most attention has been focussed on structural features of the spine in developing anatomical classifications. Features such as the apex or magnitude of a curvature or its rotation are important clinical signs and are widely used in surgical practice. This paper reviews the different classification reported but make no attempt to justify one as being ideal. However, since the biological processes contributing to the deformity and its subsequent natural history are still unclear, it remains difficult to develop a fully reliable and all embracing system of classification.

Age of Onset↗

PubMed2002

Appropriate medical data categorization for data mining classification techniques.

Some data mining (DM) methods, or software tools, require normalized data, others rely on categorized data, and some can accommodate multiple data scales. Each DM technique has a specific background theory; therefore, different results are expected when applying multiple methods. The purpose of this study is to find the data format appropriate for each DM classification technique for wider applications, and efficiently to obtain trustworthy results. Considering the nature of medical data, categorical variables are sometimes useful for making decisions and can make it easier to extrapolate knowledge. In this study, three mathematical data categorization methods (Fusinter, minimum description length principle [MDLPC] and Chi-merge) were applied to accommodate five data mining classification techniques (statistics discriminant analysis, supervised classification with Neural Networks, Decision trees, Genetic supervised clustering and Bayesian classification [probability neural networks; PNN]) using a heart disease database with four types of data (continuous data, binary data, nominal data, and ordinal data). Compared with original or normalized data, data categorized by the MDLPC categorization method was found to perform better in most of the DM classification techniques used in this study. Categorical data is good for most DM classification techniques (e.g. classification of disease and non-disease groups) and is relatively easy to use for extracting medical knowledge.

Bayes Theorem↗

PubMed2005

Classification of somatization and functional somatic symptoms in primary care.

OBJECTIVE: A substantial proportion of patients found in primary care complain of physical symptoms not attributable to any known conventionally defined disorder, that is, medically unexplained or functional somatic symptoms. The objective of this paper is to outline the problems with the current classification and propose a classification more suitable for primary health care. METHOD: We refer to and discuss relevant literature including papers on our own research on the topic in the light of our experiences from major projects on somatizing patients in primary health care. RESULTS: Functional somatic symptoms may impose severe suffering on the patient and are costly for society because of high health-care utilization, lost working years and social expenses. At present, studies on functional somatic symptoms and disorders and their treatment are hampered by lack of a valid and reliable diagnostic classification. The diagnostic categories of somatoform disorders are overlapping. Thus, the present situation is that patients with identical symptoms and clinical pictures may receive different diagnostic labels depending on the focus of interests of the assessing physician. A particular problem in primary care is that the somatoform diagnostic categories only include persistent cases and do not offer the opportunity for classification of the patients with short-symptom duration found in this setting. We present a framework for a new descriptive classification of functional somatic symptoms and unfounded illness worrying, and outline a new classification that covers the whole spectrum of severity seen in clinical practice. CONCLUSION: A precondition for an appropriate management of patients with functional somatic symptoms is a valid taxonomy common for all medical specialties facilitating cooperative care. Classification systems as outlined in this paper may be a candidate for such a system, but it should be subject to further evaluation in research.

Humans↗

PubMed2004

Neural attractor network for application in visual field data classification.

The purpose was to introduce a novel method for computer-based classification of visual field data derived from perimetric examination, that may act as a 'counsellor', providing an independent 'second opinion' to the diagnosing physician. The classification system consists of a Hopfield-type neural attractor network that obtains its input data from perimetric examination results. An iterative relaxation process determines the states of the neurons dynamically. Therefore, even 'noisy' perimetric output, e.g., early stages of a disease, may eventually be classified correctly according to the predefined idealized visual field defect (scotoma) patterns, stored as attractors of the network, that are found with diseases of the eye, optic nerve and the central nervous system. Preliminary tests of the classification system on real visual field data derived from perimetric examinations have shown a classification success of over 80%. Some of the main advantages of the Hopfield-attractor-network-based approach over feed-forward type neural networks are: (1) network architecture is defined by the classification problem; (2) no training is required to determine the neural coupling strengths; (3) assignment of an auto-diagnosis confidence level is possible by means of an overlap parameter and the Hamming distance. In conclusion, the novel method for computer-based classification of visual field data, presented here, furnishes a valuable first overview and an independent 'second opinion' in judging perimetric examination results, pointing towards a final diagnosis by a physician. It should not be considered a substitute for the diagnosing physician. Thanks to the worldwide accessibility of the Internet, the classification system offers a promising perspective towards modern computer-assisted diagnosis in both medicine and tele-medicine, for example and in particular, with respect to non-ophthalmic clinics or in communities where perimetric expertise is not readily available.

Diagnosis, Computer-Assisted↗

PubMed2005

On the quality of tree-based protein classification.

MOTIVATION: Phylogenetic analysis of protein sequences is widely used in protein function classification and delineation of subfamilies within larger families. In addition, the recent increase in the number of protein sequence entries with controlled vocabulary terms describing function (e.g. the Gene Ontology) suggests that it may be possible to overlay these terms onto phylogenetic trees to automatically locate functional divergence events in protein family evolution. Phylogenetic analysis of large datasets requires fast algorithms; and even 'fast', approximate distance matrix-based phylogenetic algorithms are slow on large datasets since they involve calculating maximum likelihood estimates of pairwise evolutionary distances. There have been many attempts to classify protein sequences on the family and subfamily level without reconstructing phylogenetic trees, but using hierarchical clustering with simpler distance measures, which also produce trees or dendrograms. How can these trees be compared in their ability to accurately classify protein sequences? RESULTS: Given a 'reference classification' or 'group membership labels' for a set of related protein sequences as well as a tree describing their relationships (e.g. a phylogenetic tree), we propose a method for dividing the tree into monophyletic or paraphyletic groups so as to optimize the correspondence between the reference groups and the tree-derived groups. We call the achieved optimal correspondence the 'accuracy of a tree-based classification (TBC)', which measures the ability of a tree to separate proteins of similar function into monophyletic or paraphyletic groups. We apply this measure to compare classical NJ and UPGMA phylogenetic trees with the trees obtained from hierarchical clustering using different protein similarity measures. Our preliminary analysis on a set of expert-curated protein families and alignments suggests that there is no uniformly superior algorithm, and that simple protein similarity measures combined with hierarchical clustering produce trees with reasonable and often the most accurate TBC. We used our measure to help us to design TIPS, a tree-building algorithm, based on agglomerative clustering with a similarity measure derived from profile scoring. TIPS is comparable with phylogenetic algorithms in terms of classification accuracy and is much faster on large protein families. Due to its time scalability and acceptable accuracy, TIPS is being used in the large-scale PANTHER protein classification project. The trees produced by different algorithms for different protein families can be viewed at http://panther.appliedbiosystems.com/pub/tree_quality/trees.jsp. For every tree and every level of classification granularity we provide the optimal TBC along with the reference classification. AVAILABILITY: The script that evaluates the accuracy of TBC is available at http://panther.appliedbiosystems.com/pub/tree_quality/index.jsp

Algorithms↗

PubMed2005

Regularized ROC method for disease classification and biomarker selection with microarray data.

MOTIVATION: An important application of microarrays is to discover genomic biomarkers, among tens of thousands of genes assayed, for disease classification. Thus there is a need for developing statistical methods that can efficiently use such high-throughput genomic data, select biomarkers with discriminant power and construct classification rules. The ROC (receiver operator characteristic) technique has been widely used in disease classification with low-dimensional biomarkers because (1) it does not assume a parametric form of the class probability as required for example in the logistic regression method; (2) it accommodates case-control designs and (3) it allows treating false positives and false negatives differently. However, due to computational difficulties, the ROC-based classification has not been used with microarray data. Moreover, the standard ROC technique does not incorporate built-in biomarker selection. RESULTS: We propose a novel method for biomarker selection and classification using the ROC technique for microarray data. The proposed method uses a sigmoid approximation to the area under the ROC curve as the objective function for classification and the threshold gradient descent regularization method for estimation and biomarker selection. Tuning parameter selection based on the V-fold cross validation and predictive performance evaluation are also investigated. The proposed approach is demonstrated with a simulation study, the Colon data and the Estrogen data. The proposed approach yields parsimonious models with excellent classification performance.

Algorithms↗

PubMed1982

The relationship between classification and questioning strategies among adults.

Adults ranging from 30 to 90 were administered the Twenty Questions Task to evaluate questioning strategies and the Picture Pairing Test to assess classification preferences. With respect to the Twenty Questions Task, the results indicated that the percentage of constraint-seeking questions decreased while the percentage of hypothesis-testing questions increased across age. With respect to classification, the results indicated that the use of similarity-based classifications decreased while the use of complementary-based classification increased across age. Further, there was significant relationship between questioning strategy and classification preference. Individuals who asked constraint-seeking questions tended to use similarity-based classifications and those who asked hypothesis-testing questions tended to use complementary-based classifications.

Adult↗