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PubMed2006

Comparison of methodologies for calculating quality measures based on administrative data versus clinical data from an electronic health record system: implications for performance measures.

New reimbursement policies and pay-for-performance programs to reward providers for producing better outcomes are proliferating. Although electronic health record (EHR) systems could provide essential clinical data upon which to base quality measures, most metrics in use were derived from administrative claims data. We compared commonly used quality measures calculated from administrative data to those derived from clinical data in an EHR based on a random sample of 125 charts of Medicare patients with diabetes. Using standard definitions based on administrative data (which require two visits with an encounter diagnosis of diabetes during the measurement period), only 75% of diabetics determined by manually reviewing the EHR (the gold standard) were identified. In contrast, 97% of diabetics were identified using coded information in the EHR. The discrepancies in identified patients resulted in statistically significant differences in the quality measures for frequency of HbA1c testing, control of blood pressure, frequency of testing for urine protein, and frequency of eye exams for diabetic patients. New development of standardized quality measures should shift from claims-based measures to clinically based measures that can be derived from coded information in an EHR. Using data from EHRs will also leverage their clinical content without adding burden to the care process.

Blood Pressure↗

PubMed1994

Tutorial: planning for data collection. Part II: Designing the study.

Part II of this three-part tutorial focuses on the logistics of data collection. The author presents a checklist of things to consider when planning the details of a data collection effort; touches on the topics of bias and stratification; discusses examples of popular data collection methods; and points out some common pitfalls in data collection, offering practical tips on how to avoid them.

Data Collection↗

PubMedDate not supplied

X-ray powder diffraction data for selected drugs: furosemide, hydrochlorothiazide, naproxen, naproxen sodium, propranolol hydrochloride, and the halopheniramine maleates.

X-ray powder diffraction data for 9 commonly used drug substances are reported. The data for furosemide, hydrochlorothiazide, propranolol hydrochloride, dexchlorpheniramine maleate, and brompheniramine maleate have been indexed by reference to published crystal structure data. The racemic modifications of propranolol hydrochloride and brompheniramine maleate are shown to exist as racemic compounds rather than racemic mixtures.

Chlorpheniramine↗

PubMedDate not supplied

Pulsed wave-Doppler ultrasonographic evaluation of the common carotid artery in the resting horse: physiologic data.

A pulsed wave-Doppler ultrasonographic evaluation of common carotid arterial blood flow was carried out on 63 healthy Italian Saddlebred horses. Vessel diameter and tracing morphology were evaluated and blood flow parameters (systolic, diastolic and mean velocity, acceleration and deceleration of the systolic wave, carotid pulse volume) were calculated and correlated with class variables (sex, age and body weight). On the basis of the presence of an incisure in the ascending branch of the systolic curve, subjects were divided in two groups: one with a bifid systolic curve and the other with a monophasic aspect. Correlations between: 1) diameter of the vessel and body weight and 2) carotid pulse volume and flow velocity (systolic, diastolic and mean) were found. A greater systolic pulse volume was found in male subjects, in subjects with greater body weight and in those which had a monophasic systolic wave.

Acceleration↗

PubMed1995

Interelectrode coherences from nearest-neighbor and spherical harmonic expansion computation of laplacian of scalp potential.

Interchannel coherence is a measure of spatial extent of and timing relationships among cerebral electroencephalogram (EEG) generators. Interchannel coherence of referentially recorded potentials includes components due to volume conduction and reference site activity. The laplacian of the potential is reference independent and decreases the contribution of volume conduction. Interchannel coherences of the laplacian should, therefore, be less than those of referentially recorded potentials. However, methods used to compute the laplacian involve forming linear combinations of multiple recorded potentials, which may inflate interchannel coherences. WE compared 3 methods of computing the laplacian: (1) modified Hjorth (4 equidistant neighbors to each electrode), (2) Taylor's series (4 nonequidistant neighbors), and (3) spherical harmonic expansion (SHE). Average interchannel coherence introduced by computing the laplacian was less for nearest-neighbor methods (0.0207 +/- 0.0766) but still acceptable for the SHE method (0.0337 +/- 0.0865). Average interchannel coherence for simulated EEG (random data plus a common 10 Hz signal) was less for laplacian than for referential data because of removal of the common referential signal. Interchannel coherences of background EEG and partial seizure activity were less with the laplacian (any method) than with referential recordings. Laplacians calculated from the SHE do not demonstrate excessively large interchannel coherences, as have been reported for laplacians from spherical splines.

Brain↗

PubMed2000

Multivariate modeling of missing data within and across assessment waves.

Missing data constitute a common but widely underappreciated problem in both cross-sectional and longitudinal research. Furthermore, both the gravity of the problems associated with missing data and the availability of the applicable solutions are greatly increased by the use of multivariate analysis. The most common approaches to dealing with missing data are reviewed, such as data deletion and data imputation, and their relative merits and limitations are discussed. One particular form of data imputation based on latent variable modeling, which we call Multivariate Imputation, is highlighted as holding great promise for dealing with missing data in the context of multivariate analysis. The recent theoretical extension of latent variable modeling to growth curve analysis also permitted us to extend the same kind of solution to the problem of missing data in longitudinal studies. Data simulations are used to compare the results of multivariate imputation to other common approaches to missing data.

Bias↗

PubMed1994

[The concept of a common medical information space: a new technology of integrated data for the improvement of health].

The concept of the common medical information space proposes that there are available health data kept in the data bases of various automatic medical systems. This data integration is achieved by integrating computers into the network, which will make a regular exchange of data among the functionally related medical institutions. The above concept of the common medical informational space is a basis for organizing a comprehensive monitoring for the health status of children (including the ecomedical aspect) at the basically new technological level, creating conditions for practical implementation of the concept of the continuum of the developing body's states, which will take into account the influence of many interacting factors on the developing fetus and child.

Medical Informatics↗

PubMed1997

On the pattern of organ growth in the common tern (Sterna hirundo).

Data are presented on the pattern of organ growth in the Common Tern, a semi-precocial bird species with a high growth rate, and are compared with data from some bird species within the altricial-precocial spectrum. The data show that a high growth rate is linked to a growth pattern characterized by a rapid early development of the digestive organs and a late development of pectoral muscles and feathers. These results suggest that the growth rate is most likely restricted by the capacity to ingest and digest food. It also appears that the organ growth pattern is more closely related to the growth rate than to the degree of precocity.

Animals↗

PubMed1990

Lytic units reconsidered: pitfalls in calculation and usage.

51Chromium release-derived cytotoxicity data yield curvilinear plots when the x axis displays the effector:target ratio and the y axis displays the percentage of cytotoxicity. To facilitate data analysis, several biomathematical models (simple linear regression, exponential fit, and Von Krogh) have been used to express these cytotoxicity curves as a single numerical value, termed the lytic unit. Other than using raw cytotoxicity data, the lytic unit has been the most common method of data presentation in human and animal tumor immune studies involving natural killer cells, lymphokine-activated killer cells, and cytotoxic T cells. Unfortunately, the models for determining lytic unit values incorporate assumptions and methods of calculation that can result in inaccurate model-predicted cytotoxicity in comparison with the actual observed cytotoxicity data. Even when the model is accurate in predicting cytotoxicity values (i.e., the nonlinear regression-calculated three-parameter Von Krogh model), comparisons between donors of minimally different or highly different cytotoxicity are still fraught with potential error due to statistically verifiable violations of assumptions of parallelism. Although more cumbersome, donor cytotoxicity comparisons using a range of effector:target ratios are not subject to the above problems. Researchers may therefore want to reconsider the use of lytic units when evaluating and reporting cytotoxicity data.

Chromium Radioisotopes↗

PubMed2005

The CCPN data model for NMR spectroscopy: development of a software pipeline.

To address data management and data exchange problems in the nuclear magnetic resonance (NMR) community, the Collaborative Computing Project for the NMR community (CCPN) created a "Data Model" that describes all the different types of information needed in an NMR structural study, from molecular structure and NMR parameters to coordinates. This paper describes the development of a set of software applications that use the Data Model and its associated libraries, thus validating the approach. These applications are freely available and provide a pipeline for high-throughput analysis of NMR data. Three programs work directly with the Data Model: CcpNmr Analysis, an entirely new analysis and interactive display program, the CcpNmr FormatConverter, which allows transfer of data from programs commonly used in NMR to and from the Data Model, and the CLOUDS software for automated structure calculation and assignment (Carnegie Mellon University), which was rewritten to interact directly with the Data Model. The ARIA 2.0 software for structure calculation (Institut Pasteur) and the QUEEN program for validation of restraints (University of Nijmegen) were extended to provide conversion of their data to the Data Model. During these developments the Data Model has been thoroughly tested and used, demonstrating that applications can successfully exchange data via the Data Model. The software architecture developed by CCPN is now ready for new developments, such as integration with additional software applications and extensions of the Data Model into other areas of research.

Computer Graphics↗

PubMedDate not supplied

The effect of vascular curvature on three-dimensional reconstruction of intravascular ultrasound images.

OBJECTIVE: To characterize the effect of vessel curvature on the geometric accuracy of conventional three-dimensional reconstruction (3DR) algorithms for intravascular ultrasound image data. BACKGROUND: A common method of 3DR for intravascular ultrasound image data involves geometric reassembly and volumetric interpolation of a spatially related sequence of tomographic cross sections generated by an ultrasound catheter withdrawn at a constant rate through a vascular segment of interest. The resulting 3DR is displayed as a straight segment, with inherent vascular curvature neglected. Most vascular structures, however, are not straight but curved to some degree. For this reason, vascular curvature may influence the accuracy of computer-generated 3DR. METHODS: We collected image data using three different intravascular ultrasound catheters (2.9 Fr, 4.3 Fr, 8.0 Fr) during a constant-rate pullback of 1 mm/sec through tubing of known diameter with imposed radii of curvature ranging from 2 to 10 cm. Image data were also collected from straight tubing. Image data were digitized at 1.0-mm intervals through a length of 25 mm. Two passes through each radius of curvature were performed with each intravascular ultrasound catheter. 3DR lumen volume for each radius of curvature was compared to that theoretically expected from a straight cylindrical segment. Differences between 3DR lumen volume of theoretical versus curved (actual) tubes were quantified as absolute percentage error and categorized as a function of curvature. Tubing deformation error was quantified by quantitative coronary angiography (QCA). RESULTS: Volumetric errors ranged from 1% to 35%, with an inverse relationship demonstrated between 3DR lumen volume and segmental radius of curvature. Higher curvatures (r < 6.0 cm) induced greater lumen volume error when compared to lower curvatures (r > 6.0 cm). This trend was exhibited for all three catheters and was shown to be independent of tubing deformation artifacts. QCA-determined percentage diameter stenosis indicated no deformation error as a function of curvature. Total volumetric error contributed by tubing deformation was estimated to be 0.05%. CONCLUSIONS: Catheter-dependent geometrical error arises in three-dimensionally reconstructed timed linear pullbacks of intravascular ultrasound images due in part to uniplanar vascular curvature. Three-dimensional reconstruction of timed linear pullbacks is robust for vessels with low radii of curvature; however, careful interpretation of three-dimensional reconstructions from timed linear pullbacks for higher radii of curvature is warranted. These data suggest that methods of spatially correct three-dimensional reconstruction of intravascular ultrasound images should be considered when more pronounced vascular curvature is present.

Algorithms↗

PubMed2004

Investing in surveillance: a fundamental tool of public health.

OBJECTIVES: The WHO Global InfoBase assembles country-level chronic disease risk factor prevalence data from WHO's member states. METHODS: The focus of this report is recent, nationally representative data. The risk factors of choice are those that make the greatest contribution to mortality and morbidity from chronic disease, can be changed through primary intervention and are easily measured in populations. RESULTS: Eight risk factors fit these criteria. They are: tobacco and alcohol use, patterns of physical inactivity, low fruit/vegetable intake, obesity, blood pressure, cholesterol and diabetes. Important to the data collection is the need to display prevalence data for these eight risk factors by age group(s) and sex and with some measure of the uncertainty of the estimate. CONCLUSIONS: This tool can be used by countries to evaluate the quality of the data that they have for chronic disease surveillance. The aim is to improve risk factor data quality and to standardize data, either through common survey instruments or by using existing country data to model risk factor estimates. These "harmonized" estimates will allow for comparisons over time and between countries.

Causality↗

PubMed1998

Estimation of confidence intervals for area under the curve from destructively obtained pharmacokinetic data.

The area under the curve (AUC) of the concentration-time curve for a drug or metabolite, and the variation associated with the AUC, are primary results of most pharmacokinetic (PK) studies. In nonclinical PK studies, it is often the case that experimental units contribute data for only a single time point. In such cases, it is straightforward to apply noncompartmental methods to determine an estimate of the AUC. In this report, we investigate noncompartmental estimation of the AUC using the long-trapezoidal rule during the elimination phase of the concentration-time profile, and we account for the underlying distribution of data at each sampling time. For data that follow a normal distribution, the log-trapezoidal rule is applied to arithmetic means at each time point of the elimination phase of the concentration-time profile. For data that follow a lognormal distribution, as is common with PK data, the log-trapezoidal rule is applied to geometric means at each time point during elimination. Since the log-trapezoidal rule incorporates nonlinear combinations of mean concentrations at each sampling time, obtaining an estimate of the corresponding variation about the AUC is not straightforward. Estimation of this variance is further complicated by the occurrence of lognormal data. First-order approximations to the variance of AUC estimates are derived under the assumptions of normality, and lognormality, of concentrations at each sampling time. AUC estimates and variance approximations are utilized to form confidence intervals. Accuracies of confidence intervals are tested using simulation studies.

Algorithms↗

PubMed2000

Robustness of reserve selection procedures under temporal species turnover.

Complementarity-based algorithms for the selection of reserve networks emphasize the need to represent biodiversity features efficiently, but this may not be sufficient to maintain those features in the long term. Here, we use data from the Common Birds Census in Britain as an exemplar data set to determine guidelines for the selection of reserve networks which are more robust to temporal turnover in features. The extinction patterns found over the 1981-1991 interval suggest that two such guidelines are to represent species in the best sites where they occur (higher local abundance) and to give priority to the rarer species. We tested five reserve selection strategies, one which finds the minimum representation set and others which incorporate the first or both guidelines proposed. Strategies were tested in terms of their efficiency (inversely related to the total area selected) and effectiveness (inversely related to the percentage of species lost) using data on eight pairs of ten-year intervals. The minimum set strategy was always the most efficient, but suffered higher species loss than the others, suggesting that there is a trade-off between efficiency and effectiveness. A desirable compromise can be achieved by embedding the concerns about the long-term maintenance of the biodiversity features of interest in the complementarity-based algorithms.

Algorithms↗

PubMed1999

[Systematic reviews on infectious diseases. The Cochrane Collaboration].

BACKGROUND: Theoretically, doctors update their knowledge from the scientific literature, and bibliographic databases have made it possible to overcome many of the limitations with this information, but not all of them. When faced with a therapeutic issue, the practice of evidence based medicine requires the efficient access to information derived from controlled clinical trials (CCT). Reviews of the scientific literature are of increasing importance. The Cochrane Collaboration is dedicated to preparing, maintaining and disseminating updated, systematic reviews of CCTs of health care interventions, which are published in the Cochrane Library. OBJECTIVE: To describe the Cochrane Collaboration and to locate, with the greatest exhaustiveness possible, CCTs published in the journals "Enfermedades Infecciosas y Microbiología Clínica", describe their characteristics and include them in a global database of clinical trials maintained by the Cochrane Collaboration. METHODS: The CCTs were identified by systematic manual searches of all issues of the journal. A descriptive analysis of the CCTs located was made. RESULTS: A total of 24 CCTs were published in 15 years (1.6 per year), 10 were original articles and 14 were communications at congresses. All were done in Spain and the majority were done in hospitals. The most frequently researched question was antibiotic prophylaxis and all evaluated pharmaceutical interventions. The majority of the CCTs published had important information missing (phase of study, randomization, blinding, etc.). CONCLUSIONS: The identification of CCTs is a prerequisite for the development of systematic reviews. There were few clinical trials published in the 15 years of publication of this journal, and the most common characteristic is, clearly, the absence of basic data. The most common is a lack of on the phase of the clinical trial, the follow-up period, and funding sources. The idea of what experimental clinical investigation in infectious diseases is in our country needs to include the identification of CCTs published in other Spanish and international journals.

Bibliometrics↗

PubMed1977

Metastatic and histologic presentations in unknown primary cancer.

The patient with metastatic adeno- or undifferentiated carcinoma who presents with a cryptic primary is subjected to an extensive diagnostic search. These efforts apparently stem from the following assumptions: 1). The ultimately proven primary sites in such patients will occur with the same frequency as the most commonly occurring carcinomas (i.e., lung, breast, colon, prostate, etc.); and 2). Metastatic patterns and histologies seen at diagnosis are the same as for patients presenting with these more common tumors. Our data contradict these assumptions. For example, the most commonly occurring unknown primary was pancreas. Rarely occurring primaries included breast and prostate. Lung cancer was observed frequently, but the presentation was atypical because of the large proportion of female patients. In addition, the metastatic patterns at diagnosis were unusual for many of the ultimately proven primary sites. In an attempt to deal with these contradictions, a method to search for new relationships between primary site and metastatic-histologic presentations was employed. This method succeeded in placing the location of the primary cancer to above or below the diaphragm in 80% of the patients studied retrospectively. Tested prospectively in a small group of patients, the method appears to be clincally useful. Finally, in this study we have made the diagnosis, antemortem, of the primary cancer site (PCS) in only 30 of 264 patients. The failure to find the primary site, dispite extensive radiologic work-up, was disappointing to the authors, and emphasizes the difficulty of finding PCS antemortem. In our study pancreas and lung appear to be most common cryptic primary sites.

Abdomen↗

PubMed1996

Endpoint error in smoothing and differentiating raw kinematic data: an evaluation of four popular methods.

'Endpoint error' describes the erratic behavior at the beginning and end of the computed acceleration data which is commonly observed after smoothing and differentiating raw displacement data. To evaluate endpoint error produced by four popular smoothing and differentiating techniques, Lanshammar's (1982, J. Biomechanics 15, 99-105) modification of the Pezzack et al. (1977, J. Biomechanics, 10, 377-382) raw angular displacement data set was truncated at three different locations corresponding to the major peaks in the criterion acceleration curve. Also, for each data subset, three padding conditions were applied. Each data subset was smoothed and differentiated using the Butterworth digital filter, cubic spline, quintic spline, and Fourier series to obtain acceleration values. RMS residual errors were calculated between the computed and criterion accelerations in the endpoint regions. Although no method completely eliminated endpoint error, the results demonstrated clear superiority of the quintic spline over the other three methods in producing accurate acceleration values close to the endpoints of the modified Pezzack et al. (1977) data set. In fact, the quintic spline performed best with non-padded data (cumulative error = 48.0 rad s-2). Conversely, when applied to non-padded data, the Butterworth digital filter produced wildly deviating values beginning more than the 10 points from the terminal data point (cumulative error = 226.6 rad s-2). Each of the four methods performed better when applied to data subsets padded by linear extrapolation (average cumulative error = 68.8 rad s-2) than when applied to analogous subsets padded by reflection (average cumulative error = 86.1 rad s-2).

Acceleration↗

PubMed2003

caCORE: a common infrastructure for cancer informatics.

MOTIVATION: Sites with substantive bioinformatics operations are challenged to build data processing and delivery infrastructure that provides reliable access and enables data integration. Locally generated data must be processed and stored such that relationships to external data sources can be presented. Consistency and comparability across data sets requires annotation with controlled vocabularies and, further, metadata standards for data representation. Programmatic access to the processed data should be supported to ensure the maximum possible value is extracted. Confronted with these challenges at the National Cancer Institute Center for Bioinformatics, we decided to develop a robust infrastructure for data management and integration that supports advanced biomedical applications. RESULTS: We have developed an interconnected set of software and services called caCORE. Enterprise Vocabulary Services (EVS) provide controlled vocabulary, dictionary and thesaurus services. The Cancer Data Standards Repository (caDSR) provides a metadata registry for common data elements. Cancer Bioinformatics Infrastructure Objects (caBIO) implements an object-oriented model of the biomedical domain and provides Java, Simple Object Access Protocol and HTTP-XML application programming interfaces. caCORE has been used to develop scientific applications that bring together data from distinct genomic and clinical science sources. AVAILABILITY: caCORE downloads and web interfaces can be accessed from links on the caCORE web site (http://ncicb.nci.nih.gov/core). caBIO software is distributed under an open source license that permits unrestricted academic and commercial use. Vocabulary and metadata content in the EVS and caDSR, respectively, is similarly unrestricted, and is available through web applications and FTP downloads. SUPPLEMENTARY INFORMATION: http://ncicb.nci.nih.gov/core/publications contains links to the caBIO 1.0 class diagram and the caCORE 1.0 Technical Guide, which provide detailed information on the present caCORE architecture, data sources and APIs. Updated information appears on a regular basis on the caCORE web site (http://ncicb.nci.nih.gov/core).

Animals↗