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PubMed2000

Can we classify medical data dictionaries?

Medical Data Dictionaries enable a clinical information system to maintain a controlled vocabulary, to store descriptive knowledge about terms, to map between those terms and from those terms to external classifications. They support a variety of functions in the information system, ranging from structured documentation to knowledgebased functions. This paper derives a multi-axial classification for medical data dictionaries. Dictionaries are classified along 4 axes, a vocabulary axis defining vocabulary properties, an application axis which characterises the degree of linkage between dictionary and information system, a semantic axis defining the quality of inter-term relationships and finally a language axis which classifies rules for inter-term relationships in semiotic theory. As an example two existing dictionaries are classified in the model and reference is taken to the design of future dictionaries.

Artificial Intelligence↗
PubMed1986

Within- and between-person variation in dietary surveys: number of days needed to classify individuals.

The variation from day to day, between individuals and within individuals, in the consumption of energy and a variety of nutrients is presented for two groups of executive grade civil servants aged 40-49, numbering 83 and 68 and working in London in 1970-1971, and for 98 drivers and 83 conductors aged 30-67 of London's double decker buses in 1958-1967, a total of 332 men. Each man weighed and recorded his food for at least a week. The reliability with which these men could be classified into extreme thirds of the distribution of individual consumption of the various 'nutrients' or foods on the basis of a single day's or of several days' measurement was calculated. The number of days of measurement required to achieve a given reliability of classification into extreme thirds of the distribution was also estimated. The key is the ratio of the 'between-person' to the 'within-person' variance for the particular nutrient. A diagram is presented of how this ratio is related to the number of days of survey required for a given reliability. Nutrients fall into three main groups--those consumed in relatively large amounts each day (eg protein, fat), those found in moderate amounts in many or most foods but in very large quantities in a few foods (eg dietary cholesterol, calcium), and those which may not be consumed at all by some people but are taken in large quantities by others (eg alcohol). The number of days of survey required for 80 per cent reliable classification of individuals varies from 2 or 3 days for some nutrients like sugar or total carbohydrates to 2 or 3 weeks for others like dietary cholesterol or the ratio of polyunsaturated fatty acids to saturated fatty acids. One day's survey classified no nutrients with 80 per cent reliability in our data, whereas one week's survey classified most nutrients with this reliability or better, although for a few the figure is lower. The precision of a week's survey is also shown in absolute quantities such as grams as distinct from thirds of the distribution. The relevance of these observations to the use of the results of 24-hour surveys in population surveys and correlation and regression analysis is discussed.

Adult↗
PubMed1984

Stabilized binary hierarchic classifier in cytopathologic diagnosis.

A binary tree classifier (BTC) algorithm for computer-assisted cell image analysis has been developed that overcomes the problem of overtraining due to inadequate sample size/dimensionality ratio at the higher-order nodes of a hierarchic decision structure. Provisions have been introduced that ensure that decision rules created at each node are based on samples representative of the subpopulation routed to the node. These provisions eliminate problems caused by truncation effects resulting from the application of decision rules at preceding decision nodes. The BTC performs better than do single-stage classifiers in situations where the categories' mean vectors are not well separated and no equality of covariance matrices exists. In applications in which noticeable deterioration of classifier performance on test-set data is common, the classification success rate of the BTC algorithm is not statistically significantly different between the training-set and test-set data.

Cells↗
PubMedDate not supplied

Single step immunophenotyping of acute leukemias not classifiable by standard morphology and cytochemistry: a practical approach.

BACKGROUND: Immunophenotyping is at present a useful aid and often an essential step for correct diagnosis of acute leukemia and for this purpose some investigators have proposed several immunomarker panels. This approach is particularly important in the differential diagnosis of acute leukemias not classifiable by standard morphology and cytochemistry. METHODS: We have tested peripheral blood and/or bone marrow samples from 125 patients not classifiable by FAB criteria. In all the cases, the reactivities of the same panel of 17 monoclonal antibodies were analyzed by flow cytometry, using both single and double fluorescent labeling. RESULTS: Of the 125 patients investigated, 75 (60%) were classifiable as ALL, 58 as B-lineage ALL and 17 as T-lineage ALL; 33 (26.4%) as AML, of which 2 M7; 6 (4.8%) as biphenotypic and 11 (8.8%) as immunophenotypically undifferentiated. CONCLUSIONS: From a critical analysis of our cases and a review of the literature, we suggest that a panel of 9 monoclonal antibodies (CD2, CD5, CD7, CD10, CD19, CD20, CD13, CD33, CD41), is sufficient for reliable, rapid and reasonably low cost typing of acute leukemia, useful for an immediate therapeutic decision.

Acute Disease↗
PubMed1995

Sagittal plane correction in "King-classified" idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

INTRODUCTION AND AIM OF THE STUDY: Whereas Harrington instrumentation (HI) has demonstrated satisfactory frontal plane correction, sagittal plane realignment is difficult. Sagittal plane control is reported to be easier with Cotrel-Dubousset instrumentation (CDI). This study was undertaken to determine if in our series sagittal realignment was achieved with CDI in idiopathic curves classified according to King. MATERIAL AND METHODS: Ninety-seven patients with idiopathic scoliosis classified according to King and treated with CDI underwent coronal and sagittal plane analysis by an unbiased observer. The sagittal curves were measured with the Cobb method from T4-T12 (normals: +25 to +40 degrees) and L1-L5 (normals: -40 to -55 degrees). The thoracolumbar junction (TJ) was divided into an upper TJ (T10-T12) and a lower TJ (T12-L2) with normals between 0 and +10 degrees for the former and 0 and -10 degrees for the latter. RESULTS: In all types of scoliosis with associated thoracic hypokyphosis a significant realignment could be achieved, ranging from 8 degrees in King 1 and 3 curves to 19 degrees in King 4 curves. In normokyphotic curves no significant changes of the thoracic spine were measured postoperatively. Concerning the upper TJ, pathological lordosis was corrected by 7 degrees on the average, whereas correction of kyphosis ranged from 8 to 18 degrees Cobb. Pathologic kyphosis and hyperlordosis of the lower TJ showed a mean correction of 7 degrees and 11 degrees, respectively. There was no significant direct influence of CDI on the sagittal plane of the lumbar spine. CONCLUSION: The data from this study suggest that correction in the sagittal plane can be achieved with CDI in King-classified scoliotic deformities.

Follow-Up Studies↗
PubMed1997

Validity of clinic biopsy specimens in classifying histopathologic characteristics of recurrent nasopharyngeal carcinoma.

OBJECTIVE: To evaluate nasopharyngeal carcinoma resection specimens for heterogeneity of histologic patterns to determine if preoperative histologic characteristics of the clinic biopsy specimen are representative of the entire lesion. The null hypothesis is that clinic biopsy specimens are not necessarily representative. DESIGN: Preoperative clinic biopsy specimens were measured to calculate their average size. Resection specimens were then sectioned and evaluated in increments corresponding to this size. Each of these increments was then histologically classified according to the World Health Organization (WHO) criteria. This classification of the preoperative biopsy specimens was compared with that of the resection specimen as a whole. SETTING: University referral center. PATIENTS: Twenty-six consecutive patients with recurrent nasopharyngeal carcinoma who underwent surgical resection. Radiation therapy failed in all patients. MAIN OUTCOME MEASURE: The presence or absence of WHO histologic heterogeneity in the nasopharyngectomy specimen was recorded. Disparity between preoperative clinic biopsy and resection specimens was recorded. RESULTS: The mean clinic biopsy specimen size was 13.9 mm2 or less than 1% of the available surface area of the nasopharynx. Of 26 resection specimens classified in 5 increments of this size, 15 (57.7%) were a single WHO type, and 11 (42.3%) were found to be mixtures of WHO types I, II, and III. Of 16 cases with preoperative biopsy specimens available, 4 (25%) were a different WHO classification than their corresponding resection specimen. CONCLUSIONS: Most clinic biopsy specimens were representative of their corresponding tumor resection specimens in their entirety; however, tumor heterogeneity is such that some biopsy specimens will not be representative. This finding may interfere with WHO classification data determined on the basis of clinic biopsy specimens and hence confound any meaningful data on treatment outcomes. It is recommended then that multiple nasopharyngeal biopsy specimens be obtained from disparate areas of the lesion and each subjected to independent histopathologic review.

Adult↗
PubMed1979

Newer experimental methods for classifying depression. A report from the NIMH collaborative pilot study.

A total of 83 patients receiving diagnoses of major depressive disorder in the pilot phase of the National Institute of Mental Health Collaborative Study of the Psychobiology of Depression were used to evaluate two newer methods of classifying depressive disorders on the basis of family history or course. A third subtype based on family history, nonfamilial depression, was compared with the two subtypes originally proposed by Winokur and colleagues, pure depression and depression spectrum diseases. The system for classifying depressions on the basis of course and antecedent disorder, primary vs secondary depression, was also compared. These data from the pilot study indicate that two newer systems for classification have some predictive, construct, and content validity, but both are in need of further investigation before they become accepted methods for the classification of depressive disorders.

Depression↗
PubMed1996

Classifying visual field data.

We develop a prediction model for classifying an eye according to glaucoma status based on its visual field. We develop measures of both diffuse and localized defects in the visual field as potential predictors of glaucoma. To identify predictors of abnormal fields, we must describe the variability in the fields of normal eyes, hence we first model the mean, variance and correlation structures of normal fields with use of generalized estimating equations. The best measures of diffuse loss include a field's mean level, contrasts of the upper and lower halves, and contrasts of the nasal and temporal halves. Local loss is measured by the depth, area, volume and location of the field's largest defect. We develop logistic regression models to classify eyes as having glaucoma or not. We present ROC curves of the results that are highly competitive with current clinical methods of classification.

Adult↗
PubMed1998

Observer variation in classifying chest radiographs for small lung opacities and pleural abnormalities in a population sample.

BACKGROUND: The purpose of this study was to assess inter-and intraobserver variation in the radiographic categories of small lung opacities (profusion) and pleural abnormalities classified according to the ILO classification of pneumoconioses with some modifications. METHODS: Chest radiographs derived from a representative adult population sample (n = 7,095) were classified by two radiologists. Observer variation was assessed on the basis of kappa (kappa)-type statistics. RESULTS: The observers agreed on profusion categories in 69% of cases of the total material. Up to 98% of the classifications fell into the same category or deviated by no more than one category. The corresponding kappa (kappa) coefficient was 0.48 (95% CI = 0.46=0.49) and the weighted kappa 0.72. When a selected subsample was reclassified by the observers, the proportions of crude agreement on profusion of small opacities ranged from 42% to 47% (weighted kappa 0.52-0.55). The proportions of agreement on the main pleural abnormalities were 92% or over, and the corresponding kappa coefficients at least 0.73. CONCLUSION: The classification of lung opacities was subject to considerable observer variation, which calls for caution when results from different studies are compared. This variation, however, rarely exceeded one category, and thus appears to be small enough for meaningful comparisons between groups, at least within a single study.

Adult↗
PubMed1999

Analysis of the velocity curve for height by the wavelet interpolation method in children classified by maturity rate.

The Wavelet Interpolation Method (WIM) developed by Meyer ([1992] Wavelets and Operators. Cambridge: Cambridge University Press) has been proposed as an analytical method for the accurate description of longitudinal growth velocity in height and identification of the age at maximum peak velocity (MPV) in the curve. The distance curve in height was determined by interpolating the longitudinal records of 98 boys and 88 girls, 6-17 years old, with the WIM. The distance curve was then differentiated to obtain a velocity curve. Age at MPV estimated from the velocity curve was utilized as a criterion of maturity rate (timing), and five maturity groups (early, little early, average, little late and late) were defined in both sexes. Four type models were derived from the occurrence of secondary peaks (mid-growth spurt and after-growth spurt): type model A, appearance of a mid-growth spurt and MPV; type model B, appearance of an after-growth spurt and MPV; type model C, appearance of a mid-growth spurt, an after-growth spurt and MPV; and type model D, appearance of MPV only. The individual growth data of boys and girls classified by maturity rate were sorted into the four type models. The frequency of occurrence of the four type models in groups classified by maturity rate was then analyzed, and the characteristics of height growth velocity was examined in boys and girls. Am. J. Hum. Biol. 11:13-30, 1999. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗
PubMed1981

The look-up table: a classifier for cell sorters.

Currently used classifiers for flow cell sorters are described and the look-up table is introduced as such. An experimental setup of a look-up table classifier added to a commercially available cell sorter, under control of a microcomputer is described. The contents of the look-up table are obtained from contours of regions of interest. These regions are defined by the user who designates the areas on a video color display of the bivariate flow data. Since most cell clusters form elliptic or ovoid shapes in a multi-dimensional feature space this method enables a better matching of window shapes to cluster outlines, compared to conventional sort decision circuitry.

Cell Separation↗
PubMed1981

The effect of abnormal cell proportion on specimen classifier performance.

In two previous papers we developed formulas relating the performance (error rates) of a two-class specimen classifier to the performance of a preceding two-class classifier and the number of cells examined (K. R. Castleman and B. S. White, Analytical and Quantitative Cytology 2:117, 1980 and K. R. Castleman and B. S. White, Cytometry 1:156, 1980.). This analysis assumed a certain proportion (p) of abnormal cells on an abnormal specimen. In this paper we examine what happens when a system designed assuming one value of p is presented with a positive specimen having a different abnormal cell proportion. We show that the specimen false negative error rate increases dramatically as p decreases below the design value, and conversely. This suggests that the specimen classification performance of a particular system should be quoted only with reference to the abnormal cell proportion of the specimens used for testing.

Cell Separation↗
PubMed1987

Improved model for specimen classification based on single-cell classifiers.

We consider probabilistic models for specimen classification procedures based on systems which classify individual cells as normal or abnormal. The models which we consider generalize those discussed previously by Castleman and White (Anal. Quant. Cytol. 2:117-122, 1980; Cytometry 2:155-158, 1981) and by Timmers and Gelsema (Cytometry 6:22-25, 1985). In particular, they include the biologically plausible possibility that the specimen contains cells which are intermediate between the extremes of normal and abnormal. We find that if these additional cells occur differentially in normal and abnormal specimens, then specimen classification can become substantially more efficient when the cell classifier has different error rates for these cells.

Cervix Uteri↗
PubMed2001

Biopsy correlates of abnormal cervical cytology classified using the Bethesda system.

OBJECTIVE: The goal of this study was to determine the colposcopic findings underlying cytologic abnormalities classified according to the Bethesda system. METHODS: Women undergoing colposcopy for abnormal cytology at an urban teaching hospital between July 1, 1996 and December 31, 1999 had Papanicolaou smears repeated. Results were compared both with biopsy histology and with the worst histology reported after 8-26 months of follow-up. kappa statistics and Spearman's rho were calculated to determine the degree of agreement. RESULTS: Colposcopy was performed for 2263 (94%) women. Referral and repeat Pap smears were reported identically in 493 (25%) of the 1962 women with results for both. No AGUS (atypical glandular cells of uncertain significance) smears were confirmed on repeat smear, and after excluding AGUS, agreement within one grade was found in 1305 of 1854 (70%). Among the 1842 women with squamous cytologic abnormalities, biopsy revealed a lesion more severe than that suggested by referral cytology in 577 (31%) and a less severe lesion in 648 (35%); exact correspondence was found in only 646 (35%). Of 317 women with ASCUS (atypical squamous cells of uncertain significance) on referral Pap smear, a negative repeat smear, and a specific biopsy result, 95 (30%) had true negative histology, while 148 (47%) had condyloma, 56 (18%) had cervical intraepithelial neoplasia (CIN) 1, 8 (3%) had CIN 2, 10 (3%) had CIN 3, and none had cancer. Comparison of repeat smear and colposcopic biopsy yielded a kappa statistic of 0.16. CONCLUSIONS: Cytology classified according to the Bethesda system does not accurately predict histologic diagnosis.

Adolescent↗
PubMed1996

The use of amino acid patterns of classified helices and strands in secondary structure prediction.

Elements of secondary structure from known protein three-dimensional structures have been classified with respect to their environments in tertiary structures. The size of the solvent-inaccessible face of an alpha-helix and the accessibility patterns on the two sides of a beta-strand have been used to classify the secondary structures. For each class, we have derived a sequence template, giving the amino acid propensity at each position. A prediction is made by calculating the compatibility of segments of polypeptide sequence against templates for each type of secondary structure. This method predicts not only position of a secondary structure in a protein sequence but also the orientation of the secondary structure with respect to the core of the protein tertiary structure. A jack-knife test is applied to 78 proteins of known structure solved at better than 2 A resolution. It shows that this method predicts between 13% and 17% better than the methods of Lim, GOR and Chou and Fasman at the level of secondary structure. The orientations of inaccessible faces are predicted within 50 degrees of correct value for about two-thirds of alpha-helices.

Adenylate Kinase↗
PubMed1996

Carcinoembryonic antigen, tissue polypeptide antigen and neuron-specific enolase pleural levels used to classify small-cell and non-small-cell lung cancer patients by discriminant analysis.

The classification of lung cancer into small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC) is essential for disease prognosis and treatment. For this purpose, we have tried to optimize the use of three tumour markers determined on pleural effusions, to differentiate SCLC from NSCLC by means of a canonic variable, generated by discriminant analysis, including subjects with histologically proven lung cancer. Discriminant analysis was performed by using carcinoembryonic antigen, neuron-specific enolase and tissue polypeptide antigen pleural levels, determined in 65 consecutive and unselected patients, histologically classified as 49 NSCLC and 16 SCLC. To validate the formula generated, a control group of 37 lung cancer patients (10 SCLC and 27 NSCLC), enrolled subsequently, was employed. Applying the discriminant analysis to SCLC and NSCLC patients a good classification was obtained (92% rate of correct classification). The aforementioned formula, applied to the validation group, showed a 92% rate of correct classification. This method, which is rapid, inexpensive and routinely applicable to malignant pleural effusions, may be reliably used to classify lung cancer patients.

Adult↗
PubMed1994

Comparison of the polymerase region of small round structured virus strains previously classified in three antigenic types by solid-phase immune electron microscopy.

We have used a reverse transcription-polymerase chain reaction with nested sets of primers to determine the nucleotide sequences of a 166 base pair segment of the RNA polymerase region of seven strains of small round structured viruses (SRSVs) from the United Kingdom. These SRSV strains were previously classified by solid-phase immune electron microscopy into three antigenic types--UK2, UK3 and UK4, which are comparable to the prototype strains Norwalk virus, Hawaii agent, and Snow Mountain agents, respectively. Based on their sequences, the seven strains from the United Kingdom could be divided into two groups. The first group included two strains of the UK2 type along with Norwalk virus and Southampton virus and the second group included three strains of UK3 and two strains of UK4 types. Viruses in the first group showed 75.3%-77.1% nucleotide and 89.1%-94.6% amino acid identity with Norwalk virus while those of the second group showed 60.8%-63.3% nucleotide and 67.3%-69.1% amino acid identity. Nucleotide and amino acid identity within the second group ranged between 91.6%-99.4% and 96.4%-100%, respectively. These results suggest that the SRSVs antigenically related with Norwalk virus, Hawaii agent, and Snow Mountain agent, can be classified into two genotypes on the basis of their sequences in the RNA polymerase region.

Adult↗