SEARCH · Search PubMed

Results for “CLASSIFICATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,459 records · Page 81Linked to original sources

PubMed1998

Sequence-based classification scheme for the genus Legionella targeting the mip gene.

The identification and speciation of strains of Legionella is often difficult, and even the more successful chromatographic classification techniques have struggled to discriminate newly described species. A sequence-based genotypic classification scheme is reported, targeting approximately 700 nucleotide bases of the mip gene and utilizing gene amplification and direct amplicon sequencing. With the exception of Legionella geestiana, for which an amplicon was not produced, the scheme clearly and unambiguously discriminated among the remaining 39 Legionella species and correctly grouped 26 additional serogroup and reference strains within those species. Additionally, the genotypic classification of approximately 150 wild strains from several continents was consistent with their phenotypic classification, with the exception of a few strains where serological cross-reactivity was complex, potentially confusing the latter classification. Strains thought to represent currently uncharacterized species were also found to be genotypically unique. The scheme is technically simple for a laboratory with even basic molecular capabilities and equipment, if access to a sequencing laboratory is available.

Bacterial Proteins↗

PubMed2005

Assessment of band-based similarity coefficients for automatic type and subtype classification of microbial isolates analyzed by pulsed-field gel electrophoresis.

Pulsed-field gel electrophoresis (PFGE) has been the typing method of choice for strain identification in epidemiological studies of several bacterial species of medical importance. The usual procedure for the comparison of strains and assignment of strain type and subtype relies on visual assessment of band difference number, followed by an incremental assignment to the group hosting the most similar type previously seen. Band-based similarity coefficients, such as the Dice or the Jaccard coefficient, are then used for dendrogram construction, which provides a quantitative assessment of strain similarity. PFGE type assignment is based on the definition of a threshold linkage value, below which strains are assigned to the same group. This is typically performed empirically by inspecting the hierarchical cluster analysis dendrogram containing the strains of interest. This approach has the problem that the threshold value selected is dependent on the linkage method used for dendrogram construction. Furthermore, the use of a linkage method skews the original similarity values between strains. In this paper we assess the goodness of classification of several band-based similarity coefficients by comparing it with the band difference number for PFGE type and subtype classification using receiver operating characteristic curves. The procedure described was applied to a collection of PFGE results for 1,798 isolates of Streptococcus pneumoniae, which documented 96 types and 396 subtypes. The band-based similarity coefficients were found to perform equally well for type classification, but with different proportions of false-positive and false-negative classifications in their minimal false discovery rate when they were used for subtype classification.

Bacterial Typing Techniques↗

PubMed2006

Histopathological reporting of paediatric cutaneous vascular anomalies in relation to proposed multidisciplinary classification system.

BACKGROUND: The terminology applied to vascular anomalies has been variable in previously published literature making interpretation suboptimal. The International Society for the Study of Vascular Anomalies (ISSVA) has proposed a revised classification based on clinical features and histopathological findings. This classification is increasingly being accepted as clinically useful and a platform for future studies. AIMS: To examine the extent to which the ISSVA classification can be practically applied to diagnostic histopathological specimens. METHODS: Cutaneous vascular lesions received in a single paediatric pathology unit during a 2-year period (2004-5) were reviewed, including glucose transporter protein 1 (GLUT1) immunostaining where required, and lesions were reclassified according to the ISSVA classification. RESULTS: 144 specimens were identified. Appropriate full clinical information was provided in only 17% of cases at submission. Infantile haemangiomas comprised 46% of cases, 18% of which were regressive type, initially inaccurately identified as vascular malformations before GLUT1 immunostaining. 30% of lymphatic malformations and all lymphovenous malformations were previously classified as vascular malformations, not otherwise specified. CONCLUSIONS: The ISSVA classification of vascular anomalies provides a useful framework for histopathologists to classify vascular anomalies. However, meaningful and appropriate use of such a system is dependent on the adequacy of clinical information provided and routine use of immunohistochemical markers.

Biomarkers, Tumor↗

PubMed2000

The impact of area deprivation on differences in health: does the choice of the geographical classification matter?

OBJECTIVE: Many studies show the average health status in deprived areas to be poorer and the use of health care to be higher, but there is hardly any information on the impact of the geographical classification on the size of these differences. This study examines the impact of the geographical classification on the clustering of poor health per area and on the size of the differences in health by area deprivation. DESIGN: Data on self reported health regarding 5121 people were analysed using three classifications: neighbourhoods, postcode sectors and boroughs. Multilevel logistic models were used to determine the clustering of poor health per area and the size of the differences in health by area deprivation, without and subsequently with adjustment for individual socioeconomic status. SETTING: General population aged 16 years and over of Amsterdam, The Netherlands. MAIN OUTCOME MEASURES: Self rated health, mental symptoms (General Health Questionnaire, 12-item version), physical symptoms and long term functional limitations. MAIN RESULTS: The clustering of poor health is largest in neighbourhoods and smallest in postcode sectors. Health differences by area deprivation differ only slightly for the three geographical classifications, both with and without adjustment for individual socioeconomic status. CONCLUSIONS: In this study, the choice of the geographical classification affects the degree of clustering of poor health by area but it has hardly any impact on the size of health differences by area deprivation.

Adolescent↗

PubMed2005

An aetiological classification of birth defects for epidemiological research.

BACKGROUND: Congenital anomaly registers collect data on antenatally and postnatally detected anomalies for surveillance, research, and public health purposes. Each anomaly is coded using the International Statistical Classification of Diseases and Related Health Problems (ICD-9/ICD-10) based on body systems, allowing accurate comparisons between registers for individual anomalies. When commencing an environmental, epidemiological study, it became clear to us that there is no standard classification that takes aetiology into account. This paper describes a new classification for use in studies addressing aetiology. METHOD: A classification system was evolved and piloted using cases in a study of geographical variation in congenital anomaly prevalence.1 Cases that were difficult to categorise were noted, and after discussion with a team of experts, the classification was adjusted accordingly. RESULTS AND CONCLUSION: A robust, hierarchical method of classifying birth defects into eight categories has been produced, for use at source of data registration in conjunction with, but independent of, ICD coding.

Congenital Abnormalities↗

PubMed2003

Errors in general practice: development of an error classification and pilot study of a method for detecting errors.

OBJECTIVE: To describe a classification of errors and to assess the feasibility and acceptability of a method for recording staff reported errors in general practice. DESIGN: An iterative process in a pilot practice was used to develop a classification of errors. This was incorporated in an anonymous self-report form which was then used to collect information on errors during June 2002. The acceptability of the reporting process was assessed using a self-completion questionnaire. SETTING: UK general practice. PARTICIPANTS: Ten general practices in the North East of England. MAIN OUTCOME MEASURES: Classification of errors, frequency of errors, error rates per 1000 appointments, acceptability of the process to participants. RESULTS: 101 events were used to create an initial error classification. This contained six categories: prescriptions, communication, appointments, equipment, clinical care, and "other" errors. Subsequently, 940 errors were recorded in a single 2 week period from 10 practices, providing additional information. 42% (397/940) were related to prescriptions, although only 6% (22/397) of these were medication errors. Communication errors accounted for 30% (282/940) of errors and clinical errors 3% (24/940). The overall error rate was 75.6/1000 appointments (95% CI 71 to 80). The method of error reporting was found to be acceptable by 68% (36/53) of respondents with only 8% (4/53) finding the process threatening. CONCLUSION: We have developed a classification of errors and described a practical and acceptable method for reporting them that can be used as part of the process of risk management. Errors are common and, although all have the potential to lead to an adverse event, most are administrative.

Attitude of Health Personnel↗

PubMed2005

Breast lesion detection and classification: comparison of screen-film mammography and full-field digital mammography with soft-copy reading--observer performance study.

PURPOSE: To retrospectively compare screen-film and full-field digital mammography with soft-copy interpretation for reader performance in detection and classification of breast lesions in women in a screening program. MATERIALS AND METHODS: Regional ethics committee approved the study; signed patient consents were obtained. Two-view mammograms were obtained with digital and screen-film systems at previous screening studies. Six readers interpreted images. Interpretation included Breast Imaging Reporting and Data System (BI-RADS) and five-level probability-of-malignancy scores. A case was one breast, with two standard views acquired with both screen-film mammography and digital mammography. The standard for an examination with normal findings was classification of normal (category 1) assigned by two independent readers; for cases with benign findings, the standard was benign results at diagnostic work-up in patients who were recalled. Cases with normal or benign findings that manifested as neither interval cancer nor as cancer at subsequent screening were considered the standard. All cancers were confirmed histologically. Images were interpreted by readers in two sessions 5 weeks apart; the same case was not seen twice in any session. Receiver operating characteristic (ROC) analysis and, for a given true-positive fraction, 2 x 2 table analysis and the McNemar test were used. For binary outcome, classification of BI-RADS category 3 or higher was defined as positive for cancer. RESULTS: Cases with proved findings (n = 232) were displayed: 46 with cancers, 88 with benign findings, and 98 with normal findings. ROC analysis for all readers and all cases revealed a higher area under ROC curve (A(z)) for digital mammography (0.916) than for screen-film mammography (0.887) (P = .22). Five of six readers had a higher performance rating with digital mammography; one of five demonstrated a significant difference in favor of digital mammography with A(z) values; two showed a significant difference in favor of digital mammography with ROC analysis for a given false-positive fraction (P = .01 and .03, respectively). For cases with cancer, digital mammography resulted in correct classification of an average of three additional cancers per reader. For digital versus screen-film mammography, 2 x 2 table analysis for cancers revealed a higher true-positive rate; for benign masses, a higher true-negative rate. Neither of these differences nor any others from analysis of subgroups between the modalities were significant. CONCLUSION: Digital mammography allowed correct classification of more breast cancers than did screen-film mammography. A(z) value was higher for digital mammography; this difference was not significant.

Aged↗

PubMed1995

Fetal cleft lip with and without cleft palate: US classification and correlation with outcome.

PURPOSE: To develop a prenatal ultrasonographic (US) classification of cleft lip with or without cleft palate (CL-P) and correlate the classification with fetal outcome. MATERIALS AND METHODS: During a 5-year period (1988 to 1993), 65 fetuses with CL-P were identified with prenatal US at one of two referral centers for high-risk obstetric cases. Sonograms from each case were prospectively and retrospectively evaluated. Clefts were classified into one of five categories: type 1, cleft lip alone (n = 5); type 2, unilateral cleft lip and palate (n = 15); type 3, bilateral cleft lip and palate (n = 20); type 4, midline cleft lip and palate (n = 21); and type 5, facial defects associated with amniotic bands or limb-body-wall complex (n = 4). RESULTS: The US classification correlated with severity of defect and fetal outcome. Type 4 and 5 clefts were universally associated with concurrent anomalies and a fetal outcome, type 1 clefts with a lower rate of anomalies (20%), and type 2 and 3 clefts with intermediate prognosis. Chromosome abnormalities also varied with the type of cleft as follows: type 1, 0%; type 2, 20%; type 3, 30%; type 4, 52%; and type 5, 0%. CONCLUSION: Prenatal classification of fetal CL-P correlates with fetal outcome. This classification should help counseling and management.

Abnormalities, Multiple↗

PubMed2004

Robust classification of renal cell carcinoma based on gene expression data and predicted cytogenetic profiles.

Renal cell carcinoma (RCC) is a heterogeneous disease that includes several histologically distinct subtypes. The most common RCC subtypes are clear cell, papillary, and chromophobe, and recent gene expression profiling studies suggest that classification of RCC based on transcriptional signatures could be beneficial. Traditionally, however, patterns of chromosomal alterations have been used to assist in the molecular classification of RCC. The purpose of this study was to determine whether it was possible to develop a classification model for the three major RCC subtypes that utilizes gene expression profiles as the bases for both molecular genetic and cytogenetic classification. Gene expression profiles were first used to build an expression-based RCC classifier. The RCC gene expression profiles were then examined for the presence of regional gene expression biases. Regional expression biases are genetic intervals that contain a disproportionate number of genes that are coordinately up- or down-regulated. The presence of a regional gene expression bias often indicates the presence of a chromosomal abnormality. In this study, we demonstrate an expression-based classifier can distinguish between the three most common RCC subtypes in 99% of cases (n = 73). We also demonstrate that detection of regional expression biases accurately identifies cytogenetic features common to RCC. Additionally, the in silico-derived cytogenetic profiles could be used to classify 81% of cases. Taken together, these data demonstrate that it is possible to construct a robust classification model for RCC using both transcriptional and cytogenetic features derived from a gene expression profile.

Carcinoma, Renal Cell↗

PubMed1998

The need for an international classification of benign prostatic hyperplasia.

An international classification of patients suffering from benign prostatic hyperplasia is essential, as we are currently unable to categorize patients there-by allowing application of the most appropriate treatment as a function of selected items. We have adopted 4 items: weight of the prostate (P); quality of life index (Q); international prostatic symptom score (S), and maximum flow rate (F). 112 patients were analyzed according to this classification and the results are presented. We have tried to develop a simple, easy to remember classification in order to easily allocate a given patient to a particular category. This proposed classification corresponds to a real 'Prostate Who's Who', which should be evaluated and improved to act as a working basis for an international classification of benign prostatic hyperplasia.

Adult↗

PubMedDate not supplied

The new imaging-based classification for describing the location of lymph nodes in the neck with particular regard to cervical lymph nodes in relation to cancer of the larynx.

For over five decades, the principle landmarks used in cervical nodal classification were clinical and defined either by palpation or found at the operative table. However during the past two decades, sectional imaging has consistently improved its quality and resolution and it has been shown that imaging can identify deep structures and adenopathy not amenable to palpation. Such disease can alter planned operative or radiation fields. In the April 1999 issue of the Archives of Otolaryngology-Head Neck Surgery, for the first time an imaging-based classification was published that gave precise anatomic landmarks for use in classifying metastatic cervical adenopathy. This classification was developed in consultation with head and neck surgeons so that the nodal levels classified by this imaging-based system would correspond closely with the nodal levels determined by utilizing the most commonly employed clinically-based classifications. This article describes this imaging-based classification and demonstrates its use with axial diagrams.

Head and Neck Neoplasms↗

PubMedDate not supplied

A new classification of the delusional misidentification syndromes.

In recent years, a great number of very different and in part contradictory terminologies and classifications of delusional misidentification syndromes (DMS) have been published. In various case reports, several authors have also made contradictory comments on questions concerning classification, etiology and assignment to a possible entity of DMS. Further development and extension of the classifications proposed during recent years did not help to eliminate discrepancies and contradictions. The classification presented here has not shown any inconsistencies so far and it allows the classification of any DMS that has been examined recently.

Diagnosis, Differential↗

PubMed2005

Classification and nomenclature of retrotransposable elements.

The classification and nomenclature of retrotransposable elements is reviewed. A comparison is made between the initial classification summarized in Capy et al. (1997b), and the more recent proposal based on the classification of the viruses (Hull, 2001). Several problems, mainly relating to the position of elements belonging to the DIRS-like or Bel-like groups, are discussed. The first classification is now out of date, and must be revisited to take account of the discovery of new elements, however the second cannot be extended to the DNA elements. There is therefore, clear evidence of the need to adopt a general and a common classification.

Animals↗

PubMed2005

Combined carotid and transcranial ultrasound findings compared with clinical classification and stroke severity in acute ischemic stroke.

BACKGROUND: The aim of this study was to assess the association between cerebral hemodynamics and the clinical picture as defined by the Oxfordshire Community Stroke Project (OCSP) classification, as well as the clinical severity as defined by the National Institute of Health Stroke Scale (NIHSS) within the first 6 h of an acute middle cerebral artery (MCA) stroke onset. METHODS: 70 unselected patients were grouped according to the OCSP classification and NIHSS. All patients immediately had extracranial and transcranial Doppler (TCD) ultrasound examinations. RESULTS: In the study population as a whole, there was a significant association between intracranial vascular pathology and the OCSP classification (p<0.001) as well as the NIHSS score (p<0.001). In patients with severe stroke, however, TCD demonstrated the hypothesized proximal MCA(1) occlusion in only 34% of patients with an OCSP-defined total anterior circulation syndrome and in 42% of patients with an NIHSS score of >or=15. In moderate stroke, the OCSP classification was misleading in almost half of the patients with a partial anterior circulation syndrome, i.e. a hypothesized distal MCA(2) occlusion suitable for thrombolysis. CONCLUSIONS: Neither the OCSP classification nor the NIHSS grading provided reliable information about the site or presence of intracranial arterial occlusion in acute stroke within the first 6 h after stroke onset in the individual patient. The results of this study strongly suggest that selection of acute ischemic stroke patients for thrombolysis should also include an assessment of cerebral hemodynamics.

Adolescent↗

PubMed2006

A new subtype classification of ischemic stroke based on treatment and etiologic mechanism.

A new subtype classification of ischemic stroke was developed to reflect recent therapeutic strategies as well as evolving concepts of stroke definitions and mechanisms. In 200 consecutive patients with acute ischemic stroke, the inter-rater reliability and proportion of subtypes of the new classification system were assessed and compared with those of the Trial of ORG 10172 in the Acute Stroke Treatment (TOAST) classification. The most frequent subtype of the new classification was atherothrombosis (n = 80, 40%), followed by stroke of undetermined etiology (n = 54, 27%), small artery disease (n = 33, 16.5%), cardioembolism (n = 26, 13%), and stroke of other determined etiology (n = 7, 3.5%). Three raters agreed to the stroke subtype diagnosis in 165 out of 200 cases and the overall kappa value was excellent (kappa = 0.82). The new classification system for brain infarction was easy to use and had high inter-rater reliability.

Adult↗

PubMed1984

Contribution to the theoretical problems of classification in the observational sciences.

The procedures of classification employed in the observational sciences, particularly in psychiatry, are situated with respect to two others: those which are utilized by the cognitive instrument and those of the logician. The problems posed in the observational sciences arise from the necessity of rendering explicit procedures which are used in situations inevitably presenting a certain degree of incertitude. A stochastic model of the patient-as-seen-by-the-observer is proposed. It is emphasized the prognostic assessment may be carried out without relying on any classification whatever, by means of an equation of multiple regression making use of symptoms as predictors. One then offers to explain why psychiatry strives to categorize symptoms and patients. Two problems are examined in the light of this discussion. The first one is whether it is better to work out a unique system of classification or to favor a plurality of such systems. In light of the preceding discussion, the latter alternative is to be preferred, whereby the notion of 'natural classification' is rejected. The second one has to do with the factors creating incertitude in the observer using a given system of classification.

Cognition↗

PubMed1993

A new classification of germ cell tumours of the testis.

The partially conflicting British and WHO classifications of testicular tumours are confusing and fail to give due prominence to their histogenesis from carcinoma in situ (CIS). Spermatocytic seminoma does not originate from CIS and should be renamed 'spermatocytoma'. All other germ cell tumours are gonocytomas arising from CIS cells which have many of the characteristics of the gonocytes of the early embryo and fetus. Gonocytomas are subdivided into seminoma, if they retain their gonocyte characteristics, or teratogenic gonocytoma if the tumour stem cell has differentiation potential. A new category of anaplastic germ cell tumour is intermediate between seminoma and teratogenic gonocytoma. The teratogenic gonocytoma is an epiblastoma if no differentiation is manifest, but may differentiate along embryonic lines into teratoma or may show extraembryonic differentiation towards yolk sac tumour or choriocarcinoma. The new classification uses unambiguous terminology and is midway between the British and WHO classifications. Those familiar with either of these classifications should have no difficulty in adapting to the new proposals, and the new classification should help others to acquire a better understanding of the biology and pathology of testicular germ cell tumours.

Humans↗

PubMed2002

Coronary plaque classification with intravascular ultrasound radiofrequency data analysis.

BACKGROUND: Atherosclerotic plaque stability is related to histological composition. However, current diagnostic tools do not allow adequate in vivo identification and characterization of plaques. Spectral analysis of backscattered intravascular ultrasound (IVUS) data has potential for real-time in vivo plaque classification. METHODS AND RESULTS: Eighty-eight plaques from 51 left anterior descending coronary arteries were imaged ex vivo at physiological pressure with the use of 30-MHz IVUS transducers. After IVUS imaging, the arteries were pressure-fixed and corresponding histology was collected in matched images. Regions of interest, selected from histology, were 101 fibrous, 56 fibrolipidic, 50 calcified, and 70 calcified-necrotic regions. Classification schemes for model building were computed for autoregressive and classic Fourier spectra by using 75% of the data. The remaining data were used for validation. Autoregressive classification schemes performed better than those from classic Fourier spectra with accuracies of 90.4% for fibrous, 92.8% for fibrolipidic, 90.9% for calcified, and 89.5% for calcified-necrotic regions in the training data set and 79.7%, 81.2%, 92.8%, and 85.5% in the test data, respectively. Tissue maps were reconstructed with the use of accurate predictions of plaque composition from the autoregressive classification scheme. CONCLUSIONS: Coronary plaque composition can be predicted through the use of IVUS radiofrequency data analysis. Autoregressive classification schemes performed better than classic Fourier methods. These techniques allow real-time analysis of IVUS data, enabling in vivo plaque characterization.

Algorithms↗