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At least 883 records · Page 49Linked to original sources
PubMed2003

Accuracy and reliability of observational gait analysis data: judgments of push-off in gait after stroke.

BACKGROUND AND PURPOSE: Physical therapists routinely observe gait in clinical practice. The purpose of this study was to determine the accuracy and reliability of observational assessments of push-off in gait after stroke. SUBJECTS: Eighteen physical therapists and 11 subjects with hemiplegia following a stroke participated in the study. METHODS: Measurements of ankle power generation were obtained from subjects following stroke using a gait analysis system. Concurrent videotaped gait performances were observed by the physical therapists on 2 occasions. Ankle power generation at push-off was scored as either normal or abnormal using two 11-point rating scales. These observational ratings were correlated with the measurements of peak ankle power generation. RESULTS: A high correlation was obtained between the observational ratings and the measurements of ankle power generation (mean Pearson r=.84). Interobserver reliability was moderately high (mean intraclass correlation coefficient [ICC (2,1)]=.76). Intraobserver reliability also was high, with a mean ICC (2,1) of.89 obtained. DISCUSSION AND CONCLUSION: Physical therapists were able to make accurate and reliable judgments of push-off in videotaped gait of subjects following stroke using observational assessment. Further research is indicated to explore the accuracy and reliability of data obtained with observational gait analysis as it occurs in clinical practice.

Adult↗
PubMed2004

Accuracy of absence of fetal breathing movements in predicting preterm birth: a systematic review.

OBJECTIVE: To determine the accuracy with which the absence of fetal breathing movements on ultrasound examination predicts spontaneous preterm birth in women with threatened preterm labor. METHODS: Data sources included Medline, Embase, Pascal, Biosis, Cochrane Library, Medion, National Research Register, SciSearch, conference papers, and manual searching of bibliographies of known primary and review articles. A study was selected if it used absence of fetal breathing movements on ultrasound to predict spontaneous preterm birth in women with threatened preterm labor but before advanced cervical dilatation. Two reviewers independently selected studies and extracted data on their characteristics, quality and accuracy. Accuracy data were used to form 2 x 2 contingency tables with birth within 48 h and within 7 days of testing as the reference standards. Likelihood ratios for a positive test (LR+) and negative test (LR-) were calculated as a measure of accuracy. RESULTS: There were eight studies, which included a total of 328 women, evaluating the accuracy of absence of fetal breathing movements in predicting spontaneous preterm birth in women with threatened preterm labor. There were differences in the methodological quality among the included studies. All were lacking in one or more item that make up an ideal test accuracy study. For women presenting with threatened preterm labor, meta-analysis showed a summary LR+ of 14.80 (95% CI, 6.30-34.79) with a corresponding summary LR- of 0.46 (95% CI, 0.36-0.58) for predicting preterm birth within 7 days, and summary LR+ of 7.84 (95% CI, 1.12-54.99) and summary LR- of 0.25 (95% CI, 0.13-0.48) for predicting preterm birth within 48 h of testing. CONCLUSION: Absence of fetal breathing movements has the potential to be a useful test in predicting preterm birth both within 7 days and within 48 h of testing. However, the available studies were deficient in their sample size and quality of methodology. Future research should be undertaken to evaluate this technology and to address the methodological deficiencies.

Female↗
PubMed2003

Classification of prostatic carcinoma with artificial neural networks using comparative genomic hybridization and quantitative stereological data.

Staging of prostate cancer is a mainstay of treatment decisions and prognostication. In the present study, 50 pT2N0 and 28 pT3N0 prostatic adenocarcinomas were characterized by Gleason grading, comparative genomic hybridization (CGH), and histological texture analysis based on principles of stereology and stochastic geometry. The cases were classified by learning vector quantization and support vector machines. The quality of classification was tested by cross-validation. Correct prediction of stage from primary tumor data was possible with an accuracy of 74-80% from different data sets. The accuracy of prediction was similar when the Gleason score was used as input variable, when stereological data were used, or when a combination of CGH data and stereological data was used. The results of classification by learning vector quantization were slightly better than those by support vector machines. A method is briefly sketched by which training of neural networks can be adapted to unequal sample sizes per class. Progression from pT2 to pT3 prostate cancer is correlated with complex changes of the epithelial cells in terms of volume fraction, of surface area, and of second-order stereological properties. Genetically, this progression is accompanied by a significant global increase in losses and gains of DNA, and specifically by increased numerical aberrations on chromosome arms 1q, 7p, and 8p.

Adenocarcinoma↗
PubMed1985

Surgically-related applications of computerized operating room data.

ORMIS data are currently used in a wide range of surgically-related applications--surgical activity reporting, graduate education and residency reporting, clinical research, surgically-related administration and surgical suite administration. Use of the system within Henry Ford Hospital has been increasing as it becomes better known and as its potential usefulness becomes better understood. Willingness to use ORMIS data depends, in large part, upon the perceived accuracy of the stored data and the ease with which these data can be retrieved and reported in a useful form. A high degree of confidence in ORMIS data has been achieved through considerable surgical staff involvement in the ongoing operation of the system. Surgeons participate in the coding of operative procedures, and the provision of surgeon-specific logs has established a feedback loop whereby surgeons can easily verify the accuracy of ORMIS data. Furthermore, special care has been taken to maintain the integrity of ORMIS data by developing extensive error detection and correction facilities. The multifaceted, successful applications reported herein show the increasing importance and usefulness of computerized data in contemporary surgical services.

Computers↗
PubMed2000

The accuracy of joint surface models constructed from data obtained with an electromagnetic tracking device.

Electromagnetic tracking devices are widely used in biomechanics. In this article a method is evaluated to construct models of articular surfaces using an electromagnetic tracking device. First, the accuracy of the space tracker was examined and optimised. Then, from several joint surfaces random points were measured and eighth degree polynomials were fitted to these measurements. To check if the fit converged well, plots of cross sections of the model with corresponding data points were examined. The accuracy of the models was determined by comparing them with computed tomography data and by reproducibility tests. All the fits converged well to the data. The root mean square (RMS) error of the models varied from 0.07 to 0. 18mm, and was proportional to the size and complexity of the surface. This was mainly due to systematic errors made by the space tracker, which were also proportional to the size and complexity of the surface.

Biomechanical Phenomena↗
PubMed1987

Fine detail in body surface potential maps: accuracy of maps using a limited lead array and spatial and temporal data representation.

In order to evaluate the accuracy with which a limited lead array can be used to estimate fine details of the thoracic distribution of cardiac potentials, we compared 192-lead body surface maps and those constructed using a subset of 32 leads. We also evaluated preservation of detail in body surface maps reconstructed following spatial and temporal data representation, a method proposed for quantitative comparison of maps. Maps were analyzed with respect to four previously reported normal map features recorded with extensive lead arrays. The maps constructed from 32 leads accurately reproduced all map features with 92% or greater accuracy. Maps constructed after spatial and temporal data representation had a reproduction accuracy of 93% and 98% respectively for two map features more than 100 microV in amplitude but accuracy with respect to the two map features less than 100 microV in amplitude was 86% and 59% respectively. The study demonstrates that a selected limited lead array permits accurate estimation of the body surface distribution of cardiac potentials even when potentials are low level or occur in regions not directly sampled by a recording electrode. To represent potentials of less than 100 microV, more coefficients would be required to permit accurate spatial and temporal representation.

Electrocardiography↗
PubMed1993

Measurement techniques in animal locomotion analysis.

Animal performance can be determined by subjective observations or objective measurements. Numerical data are only then superior to results of subjective observations when they are the result of measurements carried out to test a well-defined hypothesis or to give the answer to a clear, precisely formulated question. In the analysis of kinematics a careful evaluation of the set-up of the measurement equipment and the resulting accuracy in the data is required. Measurements in three dimensions (3D) are theoretically better than those in 2D. Practically, however, collection, analysis, interpretation and presentation of 3D data are so much more complicated that frequently 2D analysis appears to be more useful. The minimal size of markers necessary to obtain a certain accuracy in kinematic data is usually too big for practical use. Smaller markers impair accuracy. Reduction of measurement noise is obligatory when time derivatives are to be calculated. Skin movement artefacts cannot be removed by data smoothing. Forces occurring between the digits and the ground can be determined using a force plate or an instrumented shoe. A force plate is accurate, but repeated trials are necessary. Using a force shoe each ground contact results in useful data. However, the shoe itself may affect locomotion. Surface strains on long bones can be recorded relatively easily. Determination of loading forces from surface strains is complicated but can be carried out using multiple strain gauges and a post-mortem calibration test. Strain in tendons is difficult to measure due to problems in defining a'zero' or reference length.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Husbandry↗
PubMed1987

Quantitative applications of Doppler cardiography in congenital heart disease.

Doppler ultrasound has rapidly become a valuable tool in the noninvasive investigation of cardiac hemodynamics. Although based on secure principles, accurate application of this methodology to quantitative measurements necessitates a thorough understanding of both Doppler physics and instrumentation. Over the past several years a large body of clinical and animal data verifying the accuracy of Doppler determination of pressure and flow data at various sites in the cardiovascular system, as well as the potential sources of error in acquisition and interpretation of blood velocity recordings, has been published. Quantitative use of Doppler in congenital heart disease, with emphasis on limitations of existing studies and issues particular to this patient population, is reviewed.

Child↗
PubMed2004

Environmentally low-temperature kinetic and thermodynamic study of lactate dehydrogenase from Atlantic cod (G. morhua) using a 96-well microplate technique.

Analyses of temperature-dependent kinetic parameters in enzymes extracted from tissues of ectothermic animals are usually carried out within the range of physiological temperatures (0-40 degrees C). However, multisample spectrophotometers (so-called microplate readers) with efficient wide-range temperature control (including cooling) have previously been unavailable. This limits the statistical quality of the measurements. A temperature-controlled microplate was designed for a 96-well microplate reader to overcome this limitation. This so-called T-microplate is able to control assay temperature between the freezing point of a liquid sample and 60 degrees C with high stability and accuracy in any data acquisition mode. At 4 degrees C the accuracy of the temperature control was +/-0.1 degrees C and temperature homogeneity across the microplate was +/-0.3 degrees C. As examples, analyses of the temperature dependence of Michaelis-Menten (K'(PYR)(m) and substrate inhibition (K'(PYR)(si) constants for pyruvate, of the maximal rate of reaction (V'(max), of the apparent Arrhenius activation energy (E(A), and of the Gibbs free-energy change (deltaG) of lactate dehydrogenases from muscle of Atlantic cod Gadus morhua acclimated to 4 degrees C are described. The large dataset obtained allowed evaluation of a new mechanism of metabolic compensation in response to seasonal temperature change.

Animals↗
PubMed2002

Preparation of name and address data for record linkage using hidden Markov models.

BACKGROUND: Record linkage refers to the process of joining records that relate to the same entity or event in one or more data collections. In the absence of a shared, unique key, record linkage involves the comparison of ensembles of partially-identifying, non-unique data items between pairs of records. Data items with variable formats, such as names and addresses, need to be transformed and normalised in order to validly carry out these comparisons. Traditionally, deterministic rule-based data processing systems have been used to carry out this pre-processing, which is commonly referred to as "standardisation". This paper describes an alternative approach to standardisation, using a combination of lexicon-based tokenisation and probabilistic hidden Markov models (HMMs). METHODS: HMMs were trained to standardise typical Australian name and address data drawn from a range of health data collections. The accuracy of the results was compared to that produced by rule-based systems. RESULTS: Training of HMMs was found to be quick and did not require any specialised skills. For addresses, HMMs produced equal or better standardisation accuracy than a widely-used rule-based system. However, accuracy was worse when used with simpler name data. Possible reasons for this poorer performance are discussed. CONCLUSION: Lexicon-based tokenisation and HMMs provide a viable and effort-effective alternative to rule-based systems for pre-processing more complex variably formatted data such as addresses. Further work is required to improve the performance of this approach with simpler data such as names. Software which implements the methods described in this paper is freely available under an open source license for other researchers to use and improve.

Data Collection↗
PubMed1981

Early prediction of outcome in head-injured patients.

The relationship between Glasgow Coma Scale (GSC) scores obtained during the 1st week after head injury and outcome at 1 year was analyzed in 170 patients. Seventy-two of 76 patients with initial GCS scores of 3 or 4 lived, and only one had a favorable outcome. Favorable and unfavorable outcomes were almost equally divided when the initial GCS scores were in the intermediate range of 5, 6, or 7. No patients with an initial GCS score in this intermediate range that subsequently worsened had a favorable outcome, while over 80% of those improving to a score higher than 7 had a favorable outcome. Only 12% of those persisting with a score of 5, 6, or 7 for 1 week had favorable outcome. Outcome predictions using the multiple logistic model were made for this intermediate group of patients based on GCS scores and data on midline shift derived from computerized tomography (CT). The patients with initial scores of 5, 6, or 7 with midline shifts of less than 4.1 mm on initial CT scanning had a significantly higher favorable outcome rate compared with patients with a larger shift. However, outcome prediction made by combining shift data and initial GCS scores are not significantly more accurate than predictions based solely on initial GCS scores. Combining 48-hour GCS scores and shift data significantly improves predictive accuracy based only on coma scores. The data obtained by combining GCS scores at 72 hours and 1 week and shift data is marginally significant for improving accuracy of outcome predictions. It is concluded that GCS scores and shift data are highly accurate indicators of outcome in head-injured patients.

Adolescent↗
PubMedDate not supplied

The impact of unmeasured clinical variables on the accuracy of hospital report cards: a Monte Carlo study.

PURPOSE: Hospital report cards are commonly produced using administrative data. The objective of this study was to determine the impact of unmeasured clinical data on the accuracy of hospitals' report cards. METHODS: Monte Carlo simulations were based on both administrative and detailed clinical data for patients hospitalized with an acute myocardial infarction in Ontario, Canada. Data were simulated such that the true performance of each hospital was known. Both clinical and administrative risk scores were randomly generated for each patient. The ability of hospital report cards to correctly identify hospitals that truly had higher than acceptable mortality was compared when both clinical and administrative data were used and when only administrative data were used. By using Monte Carlo simulations, we were able to incrementally increase the divergence between the 2 risk scores. RESULTS: In a wide range of settings, sensitivity and specificity of hospital report cards was only negligibly greater when both administrative and clinical data were used compared to when only administrative data were used. CONCLUSIONS: Unmeasured clinical data have at most a minor impact on the accuracy of cardiac hospital report cards.

Hospital Administration↗
PubMed2002

Facial identity and facial emotions: speed, accuracy, and processing strategies in children and adults.

As yet, nearly all studies in face and facial affect recognition typically provide only data on the accuracy of processing, invariably also in the absence of reference data on abstract information processing. In this study, accuracy and speed of abstract visuo-spatial processing, face recognition, and facial emotion recognition were investigated in normal school children (7-10 years) and adults (25+/-4 years). In the age range of 7-10 years, accuracy of facial processing hardly increased, while speed did substantially increase with age. Adults, however, were substantially more accurate and faster than children. Differences between facial and abstract information processing were related to type of processing strategy, that is, configural or holistic processing versus featural or piecemeal processing. Improvement in task performance with age is discussed in terms of an enhanced efficiency of the configural organization of facial knowledge (facial information processing tasks), together with a further increase in processing capacity (all tasks). The differential developmental course of speed and accuracy levels indicates that speed is a more sensitive measure when children get older. Moreover, it also suggests that speed of performance, in addition to accuracy, might be successfully used in the assessment of clinical deficits, as has recently been demonstrated in children with autistic disorders of social contact.

Adult↗
PubMed2002

Comparison of data transformation procedures to enhance topographical accuracy in time-series analysis of the human EEG.

We describe a methodology to apply current source density (CSD) and minimum norm (MN) estimation as pre-processing tools for time-series analysis of single trial EEG data. The performance of these methods is compared for the case of wavelet time-frequency analysis of simulated gamma-band activity. A reasonable comparison of CSD and MN on the single trial level requires regularization such that the corresponding transformed data sets have similar signal-to-noise ratios (SNRs). For region-of-interest approaches, it should be possible to optimize the SNR for single estimates rather than for the whole distributed solution. An effective implementation of the MN method is described. Simulated data sets were created by modulating the strengths of a radial and a tangential test dipole with wavelets in the frequency range of the gamma band, superimposed with simulated spatially uncorrelated noise. The MN and CSD transformed data sets as well as the average reference (AR) representation were subjected to wavelet frequency-domain analysis, and power spectra were mapped for relevant frequency bands. For both CSD and MN, the influence of noise can be sufficiently suppressed by regularization to yield meaningful information, but only MN represents both radial and tangential dipole sources appropriately as single peaks. Therefore, when relating wavelet power spectrum topographies to their neuronal generators, MN should be preferred.

Artifacts↗
PubMed1999

Molecular dynamics and accuracy of NMR structures: effects of error bounds and data removal.

The effect of internal dynamics on the accuracy of nuclear magnetic resonance (NMR) structures was studied in detail using model distance restraint sets (DRS) generated from a 6.6 nanosecond molecular dynamics trajectory of bovine pancreatic trypsin inhibitor. The model data included the effects of internal dynamics in a very realistic way. Structure calculations using different error estimates were performed with iterative removal of systematically violated restraints. The accuracy of each calculated structure was measured as the atomic root mean square (RMS) difference to the optimized average structure derived from the trajectory by structure factors refinement. Many of the distance restraints were derived from NOEs that were significantly affected by internal dynamics. Depending on the error bounds used, these distance restraints seriously distorted the structure, leading to deviations from the coordinate average of the dynamics trajectory even in rigid regions. Increasing error bounds uniformly for all distance restraints relieved the strain on the structures. However, the accuracy did not improve. Significant improvement of accuracy was obtained by identifying inconsistent restraints with violation analysis, and excluding them from the calculation. The highest accuracy was obtained by setting bounds rather tightly, and removing about a third of the restraints. The limiting accuracy for all backbone atoms was between 0.6 and 0.7 A. Also, the precision of the structures increased with removal of inconsistent restraints, indicating that a high precision is not simply the consequence of tight error bounds but of the consistency of the DRS. The precision consistently overestimated the accuracy.

Amino Acids↗
PubMed1995

The accuracy of drug information from pharmaceutical sales representatives.

OBJECTIVE: To provide quantitative data about the accuracy of the information about drugs presented to physicians by pharmaceutical sales representatives. DESIGN: One hundred six statements about drugs made during 13 presentations by pharmaceutical representatives were analyzed for accuracy. Statements were rated inaccurate if they contradicted the 1993 Physicians' Desk Reference or material quoted or handed out by the sales representative. SETTING: University teaching hospital. RESULTS: Twelve (11%) of 106 statements about drugs were inaccurate. All 12 inaccurate statements were favorable toward the promoted drug, whereas 39 (49%) of 79 accurate statements were favorable (P = .005). None of 15 statements about competitors' drugs were favorable, but all were accurate, significantly P < .001) differing from statements about promoted drugs. In a survey of 27 physicians who attended these presentations, seven (26%) recalled any false statement made by a pharmaceutical representative, and 10 (37%) said information from the representatives influenced the way they prescribed drugs. CONCLUSIONS: Eleven percent of the statements made by pharmaceutical representatives about drugs contradicted information readily available to them. Physicians generally failed to recognize the inaccurate statements.

Commerce↗
PubMedDate not supplied

Agreement between patient self-report and a Veterans Affairs national pharmacy database for identifying recent exposures to antibiotics.

PURPOSE: The dramatic rise in antibiotic drug resistance among community pathogens has stimulated interest in the epidemiological relationship between antibiotic exposure and drug resistance. In assessing the strength of this relationship, studies are hampered by the lack of data on the accuracy of subject self-report of antibiotic exposure. The authors compared self-report with pharmacy dispensing data to determine the accuracy of self-reported antibiotic exposure. METHODS: The study design was a cross-sectional survey of veterans seen at the Philadelphia Veterans Affairs (VA) Medical Center in 1999 and 2000. Subjects reported exposures to antibiotics, antihypertensive drugs and nonsteroidal anti-inflammatory drugs through a structured telephone interview. The instrument included open-ended questions, condition-specific prompts and drug-specific prompts. Subject responses were linked to a national VA pharmacy database that served as the reference standard for evaluating self-reported exposures. RESULTS: The authors found that the sensitivity of self-report of antibiotic exposure increased with increasing use of prompts. A comprehensive assessment of antibiotic exposure identified 73% of antibiotic exposures, compared to 73% of antihypertensive drug exposures and 92% of nonsteroidal anti-inflammatory drug exposures. CONCLUSIONS: Assessment of antibiotic exposure appears to be comparable to assessment of other chronic and episodic drugs. Multistep assessment of exposure improves the sensitivity of assessment.

Adolescent↗
PubMed1997

Data quality objectives for surface-soil cleanup operation using in situ gamma spectrometry for concentration measurements.

In situ gamma spectrometry is an efficient method for monitoring the progress of cleanup activities for radioactive contaminants in surface soil and for evaluating the attainment of cleanup standards. However, desired data precision and accuracy must be specified for such a detection system prior to the operation to ensure that the level of uncertainty associated with the concentration measurements is acceptable. A method for developing data quality objectives is described in this paper for in situ gamma spectrometry to achieve numerical goals for data precision and accuracy for cleanup operations. Concentration measurement for a radionuclide at its cleanup level must have a precision commensurate with the importance of cleanup decisions. The 95% lower limit of detection of the system is suggested to be about one tenth the expected system response at the cleanup level. The count time required to achieve the preferred 95% lower limit of detection, and hence the desired precision, can then be determined. The accuracy error arises from the overall calibration factor, which relates the detector responses (e.g., count rate) to physical quantities of interest (e.g., radionuclide soil concentration). The major source of error for the calibration factor using in situ gamma spectrometry is the misidentification of the type of the depth profile of radionuclide concentration in soil. If surrogate radionuclides are used, such as 241Am for plutonium, the variation in the concentration ratio would be another significant source of error. Soil sampling programs performed prior to a cleanup operation will greatly reduce the accuracy error for an in situ detection system, and the analysis of system errors may determine the degree of sampling required. The planning of such a program is discussed in the study. Uncertainty analysis using a Latin Hypercube sampling technique for the calibration factor is also demonstrated. The quantitative result of the uncertainty analysis is useful for determining a nuclide's maximum peak count rate using gamma spectrum that ensures the attainment of the cleanup standard for that nuclide with a pre-specified confidence level (e.g., 95%). The cleanup operation of 239,240Pu in surface soil in the safety shot areas at the Nevada Test Site serves as an example to illustrate the data quality objectives development.

Americium↗