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At least 1,027 records · Page 57Linked to original sources
PubMed2002

The analysis of repeated multivariate binary quality of life data: a hierarchical model approach.

Many quality of life measuring instruments consist of a number of questions that are answered on ordinal scales. Often these responses are then totalled to give a summary score for each quality of life domain within the instrument. This, however, may lose valuable information about individual aspects of patient quality of life and also can have little intuitive meaning. Here we present an alternative analysis, in which dichotomized individual items of the questionnaire are analyzed. We first show how a hierarchical logistic regression model for repeated binary data can be extended to the multivariate case. We then use such a model for analyzing the prevalence of six symptoms in a palliative treatment trial in non-small-cell lung cancer. The analysis provides information about the correlations between symptoms, both between and within person. If appropriate, it also permits the estimation of a treatment effect common to all symptoms. Methods for model checking are discussed. We conclude that this methodology can provide a more intuitive and informative analysis of quality of life data than that obtained by considering summary scores.

Carcinoma, Non-Small-Cell Lung↗
PubMed2006

Evidence standards in experimental and inferential INSDC Third Party Annotation data.

The Third Party Annotation (TPA) project collects and presents high-quality annotation of nucleotide sequence. Annotation is submitted by researchers who have not themselves generated novel nucleotide sequence. In its first few years, the resource has proven to be popular with submitters from a range of biological research areas. Central to the project is the requirement for high-quality data, resulting from experimental and inferred analysis discussed in peer-reviewed publications. The data are divided into two tiers: those with experimental evidence and those with inferential evidence. Standards for TPA are detailed and illustrated with the aid of case studies.

Animals↗
PubMed2002

Three-dimensional CT angiography with multidetector CT data: study optimization, protocol design, and clinical applications in the abdomen.

The quality and flexibility of abdominal CT angiograms have been well served by advances in multidetector technology and volume rendering techniques, which allow real-time, interactive modification of high-quality data sets. We have applied this approach to many of the established and developing roles of CT and we discuss and illustrate protocol design and application.

Angiography↗
PubMed1998

An examination of self- and telephone-administered modes of administration for the Australian SF-36.

The impact of administration mode on health-related quality of life measurement instruments has received little attention, especially for the SF-36. General community members were randomly selected to complete the Australian version of the SF-36 Health Survey using either telephone or mail modes. Modes were compared across a number of indices: data collection costs; consent rates and non-consent bias; data quality (completeness of data and internal consistency reliability); and response effects. Data collection costs were lower for the telephone mode. A significantly higher consent rate was achieved with the telephone mode. Those who were younger were more likely to refuse to participate when the mail mode was adopted, while older people were more likely not to consent to the telephone mode. The rate of missing responses was higher for the mail mode, while significant differences were found between modes in internal consistency reliability estimates. Health ratings were more favorable for the telephone administration. The results are discussed in light of the advantages and disadvantages of each administration mode.

Adolescent↗
PubMed2006

Universal external RNA controls for microbial gene expression analysis using microarray and qRT-PCR.

Gene expression analysis provides significant insight to understand regulatory mechanisms of biology, yet acquisition and reproduction of quality data, as well as data confirmation and verification remain challenging due to a lack of proper quality controls across different assay platforms. We present a set of six universal external RNA quality controls for microbial mRNA expression analysis that can be applied to both DNA oligo microarray and real-time qRT-PCR including using SYBR Green and TaqMan probe-based chemistry. This set of controls was applied for Saccharomyces cerevisiae and Pseudomonas fluorescens Pf-5 microarray assays and qRT-PCR for yeast gene expression analysis. Highly fitted linear relationships between detected signal intensity and mRNA input were described. Valid mRNA detection range, from 10 to 7000 pg and from 100 fg to 1000 pg were defined for microarray and qRT-PCR assay, respectively. Quantitative estimation of mRNA abundance was tested using randomly selected yeast ORF including function unknown genes using the same source of samples by the two assay platforms. Estimates of mRNA abundance by the two methods were similar and highly correlated in an overlapping detection range from 10 to 1000 pg. The universal external RNA controls provide a means to compare microbial gene expression data derived from different experiments and different platforms for verification and confirmation. Such quality controls ensure reliability and reproducibility of gene expression data, and provide unbiased normalization reference for validation, quantification, and estimate of variation of gene expression experiments. Application of these controls also improves efficiency and facilitates high throughput applications of gene expression analysis using the qRT-PCR assay.

Animals↗
PubMed1993

The quality of epidemiological data in coronary heart disease and atherosclerosis.

There are inherent difficulties in the use of indirect observations in the epidemiology of a chronic ubiquitous disease such as atherosclerosis. Such difficulties do not condone basic errors in epidemiological methodology, the use of low quality data, a lack of precision in measurements, invalid extrapolations and inappropriate use of terminology and coronary heart disease as a surrogate or synonym of coronary atherosclerosis and bias in the interpretation of data. These errors reveal a lack of rigorous and scientific standards in the epidemiology of coronary heart disease. Analysis cannot launder such data. Independent scientists must evaluate the data in respect of precision, logic and truth.

Arteriosclerosis↗
PubMed2006

High-throughput biomonitoring of dioxins and polychlorinated biphenyls at the sub-picogram level in human serum.

We report on the use of a state-of-the-art method for the measurement of selected polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls in human serum specimens. The sample preparation procedure is based on manual small size solid-phase extraction (SPE) followed by automated clean-up and fractionation using multi-sorbent liquid chromatography columns. SPE cartridges and all clean-up columns are disposable. Samples are processed in batches of 20 units, including one blank control (BC) sample and one quality control (QC) sample. The analytical measurement is performed using gas chromatography coupled to isotope dilution high-resolution mass spectrometry. The sample throughput corresponds to one series of 20 samples per day, from sample reception to data quality cross-check and reporting, once the procedure has been started and series of samples keep being produced. Four analysts are required to ensure proper performances of the procedure. The entire procedure has been validated under International Organization for Standardization (ISO) 17025 criteria and further tested over more than 1500 unknown samples during various epidemiological studies. The method is further discussed in terms of reproducibility, efficiency and long-term stability regarding the 35 target analytes. Data related to quality control and limit of quantification (LOQ) calculations are also presented and discussed.

Chromatography, Liquid↗
PubMed1994

General principles of surgery quality control.

Randomized clinical trials are currently the most reliable research technique to generate reliable treatment data. Quality control and monitoring with statistical credibility are essential. This requires nurse data managers and coordinators and statisticians, as well as the surgeons and physicians. A well-structured operating infrastructure is key. From the surgical point of view, careful intraoperative staging and standardization of the surgical procedures are a must. Strict eligibility criteria must be documented and enforced. Finally, careful stratification for prognostic variables before randomization in phase 3 trials is essential.

Clinical Trials, Phase III as Topic↗
PubMed1995

The application of GIS in environmental health sciences: opportunities and limitations.

Understanding the complex spatio-temporal relationships between environmental pollution and disease and identifying exposures to environmental hazards in high-risk populations are essential elements of an effective environmental and public health management program. Modern computer technologies, such as geographic information systems (GIS), provide cost-effective tools for evaluating interventions and policies potentially affecting health outcomes. GIS analysis or display of environmental health data is also helpful in explaining disease patterns in terms of relationships with social, institutional, technological, and natural environments. This paper examines major issues related to the application of GIS in environmental health sciences. Specifically, the paper presents and discusses the basic principles, potential benefits, and major limitations of GIS in environmental health research. A real-world example application involving development and implementation of a prototype system called EMPHASIS (EnvironMental and Public Health datA analySIs System) to facilitate management, analysis, display, and presentation of environmental, socio-demographic, and health outcome data in Iowa is described. From the discussions and the example application, it is concluded that GIS can significantly add value to environmental and public health data in areas such as exploratory data analysis, hypotheses generation, confirmatory data analysis, and decision-making. The widespread adoption of GIS in these areas, however, is impeded by issues such as inconsistent spatial scales of the data, data quality and currency, lack of appropriate statistical functions for data analysis and interpretation, and data security and confidentiality.

Environmental Health↗
PubMed2000

Characterization of visibility and atmospheric aerosols in urban, suburban, and remote areas.

Visibility data from over the past four decades accumulated from urban areas of central Taiwan indicated that air pollutants have significantly degraded visibility in recent years. Currently, the annual average visibility in urban areas of the same region is approximately 8-10 km, while the visibility in remote areas is approximately 25-30 km. To understand how aerosols affect the visibility in this region, here we selected three sites in central Taiwan to measure the soluble ionic and carbonaceous species of PM(2.5) and PM(2.5-10) during 1997-1998. A MOUDI cascade impactor was used to measure the size distributions of atmospheric sulfate, nitrate, and carbonaceous particles. The aerosol data were then analyzed together with meteorological and air quality data. Comparing the results obtained from urban, coastal suburban and remote sites revealed that sulfate, carbonaceous species and local wind speed significantly affected the visibility in the urban area. However, sulfate concentration and humidity influenced visibility in the coastal area of central Taiwan. The particulate concentration at the remote station was roughly one-fifth of that in the city. Regression analysis results indicated that humidity is a dominant factor affecting remote visibility.

Aerosols↗
PubMed1998

Quantification in functional magnetic resonance imaging: fuzzy clustering vs. correlation analysis.

The potential of functional MRI (fMRI) data analysis using the paradigm independent fuzzy cluster analysis (FCA) applied in the time domain compared to frequently used paradigm based correlation analysis (CA) was studied with simulated and in vivo fMRI data. The performance of FCA and CA was investigated in a typical contrast-to-noise range for fMRI, ranging from 1.33 to 3.33. Using simulated fMRI data the methods were quantitatively compared in terms of generation of true positives, false positives, and the corresponding signal enhancement. Even without prior knowledge about the stimulation paradigm and the actual hemodynamic response function the performance of FCA was comparable to that of CA where extensive prior knowledge has to be added. Furthermore, discrimination of nonanticipated hemodynamic responses by FCA, such as different levels of activation and delayed response, are demonstrated in simulated and in vivo fMRI data. We demonstrate that using CA one cannot differentiate between these responses at least without extensive prior knowledge, i.e., FCA yields a more particular description of fMRI data. This may be worthwhile for analysis and optimization of data quality in fMRI as well as in the final data analysis.

Adult↗
PubMed2004

Comparative evaluation of background anthropogenic hydrocarbons in surficial sediments from nine urban waterways.

Anthropogenic hydrocarbons in surficial urban sediments derived from nonpoint sources (e.g., stormwater runoff, surface runoff, direct atmospheric deposition, and small but persistent discharges) are the principal characteristics of "urban background". Establishing the character and concentration of urban background helps determine the incremental impacts from point sources and develop successful remedial strategies. In this study, we compared the nature and amount of total extractable hydrocarbons (THC) and polycyclic aromatic hydrocarbons (PAHs), including alkylated PAHs, within 280 surficial (mostly 0-10 cm) sediments from nine, well-studied urban waterways on the East and West U.S. Coasts. These 280 sediments were predominantly impacted by urban background. All the sediments were analyzed by consistent preparation and analytical methods and met consistent data quality objectives, thereby minimizing variations attributable to methodology. The data demonstrate that the anthropogenic hydrocarbons comprising urban background from all locations exhibit a generally consistent nature, dominated by (1) a variably shaped unresolved complex mixture (UCM) within the residual (C20+) range and (2) a variable distribution of resolved 4- to 6-ring nonalkylated (parent) PAHs, mostly dominated by fluoranthene and pyrene (and exhibiting a FL/PY ratio of 0.9 +/- 0.2). The variable nature of both the THC and PAH distributions testifies that, while there is a general consistency to urban background, there are definite differences between (and even within) different urban settings. This indicates thatthere is no single "representative" urban background THC or PAH signature. The greatest mass of THC is reasonably attributable to heavy petroleum(s) comprising the UCM, whereas the greatest mass of PAHs is reasonably attributable to combustion-derived particulate matter. The mean concentration of THC attributable to urban background was 415 mg/kg (dry wt). The concentration of EPA 16-Priority Pollutant PAHs was less than 20 000 microg/kg (dry wt) in 96% of the sediments studied. Thus, sediments containing significantly more than 20000 microg/kg of the EPA 16 Priority Pollutant PAHs (or more the 30000 microg/kg of 43 parent and alkylated PAHs) should be suspected to contain PAHs not entirely attributable to urban background, unless site- or regional-specific survey data supports a different urban background concentration profile.

Cities↗
PubMed1988

Automatic phonetogram recording supplemented with acoustical voice-quality parameters.

A new method for automatic voice-quality registration is presented. The method is based on a technique called phonetography, which is the registration of the dynamic range of a voice as a function of fundamental frequency. In the new phonetogram-recording method fundamental frequency (Fo) and sound-pressure level (SPL) are automatically measured and represented in an XY-diagram. Three additional acoustical voice-quality parameters are measured simultaneously with Fo and SPL: (a) jitter in the Fo as a measure for roughness, (b) the SPL difference between the 0-1.5 kHz and the 1.5-5 kHz bands as a measure for sharpness, and (c) the vocal-noise level above 5 kHz as a measure for breathiness. With this method, the voice-quality parameter values, which may change substantially as a function of Fo and SPL, are pinned to a reference position in the patient's total vocal range. Seen as a reference tool, the phonetogram opens the possibility for a more meaningful comparison of voice-quality data. Some examples, demonstrating the dependence of the chosen quality parameters on Fo and SPL are given.

Humans↗
PubMed2002

Vital statistics as a data source.

A focus group convened at a National Institutes of Health (NIH) Stillbirth Conference discussed issues related to vital statistics as a data source on fetal mortality. Fetal death is a tragic occurence and part of the continuum of pregnancy outcomes. A primary source of data is the National Vital Statistics System fetal death component, which is routinely used to track mortality trends and to provide the context for nonrepresentative investigations. The data are also used to examine differentials in mortality by characteristics and to evaluate data quality. Issues concerning how to improve the vital statistics data include culture and context; data instrument; persons providing information; what information is available to the information provider; processing issues; and use of data. Perhaps most important is to enhance recognition of fetal death both for the individual confronting a loss and to promote research. Other studies are needed to augment the information obtainable through vital records.

Culture↗
PubMed1994

Managing the quality of managed care delivery systems.

We have developed a quantitative "score card" for measuring the quality of 130 managed care organizations. This tool is currently being used in California as part of a large scale CQI process. When quality data are compared to cost data, we observe a negative correlation between cost and quality, consistent with the industrial model that better quality and lower cost can go hand in hand.

Ambulatory Care↗
PubMed2005

Respiratory correlated cone beam CT.

A cone beam computed tomography (CBCT) scanner integrated with a linear accelerator is a powerful tool for image guided radiotherapy. Respiratory motion, however, induces artifacts in CBCT, while the respiratory correlated procedures, developed to reduce motion artifacts in axial and helical CT are not suitable for such CBCT scanners. We have developed an alternative respiratory correlated procedure for CBCT and evaluated its performance. This respiratory correlated CBCT procedure consists of retrospective sorting in projection space, yielding subsets of projections that each corresponds to a certain breathing phase. Subsequently, these subsets are reconstructed into a four-dimensional (4D) CBCT dataset. The breathing signal, required for respiratory correlation, was directly extracted from the 2D projection data, removing the need for an additional respiratory monitor system. Due to the reduced number of projections per phase, the contrast-to-noise ratio in a 4D scan reduced by a factor 2.6-3.7 compared to a 3D scan based on all projections. Projection data of a spherical phantom moving with a 3 and 5 s period with and without simulated breathing irregularities were acquired and reconstructed into 3D and 4D CBCT datasets. The positional deviations of the phantoms center of gravity between 4D CBCT and fluoroscopy were small: 0.13 +/- 0.09 mm for the regular motion and 0.39 +/- 0.24 mm for the irregular motion. Motion artifacts, clearly present in the 3D CBCT datasets, were substantially reduced in the 4D datasets, even in the presence of breathing irregularities, such that the shape of the moving structures could be identified more accurately. Moreover, the 4D CBCT dataset provided information on the 3D trajectory of the moving structures, absent in the 3D data. Considerable breathing irregularities, however, substantially reduces the image quality. Data presented for three different lung cancer patients were in line with the results obtained from the phantom study. In conclusion, we have successfully implemented a respiratory correlated CBCT procedure yielding a 4D dataset. With respiratory correlated CBCT on a linear accelerator, the mean position, trajectory, and shape of a moving tumor can be verified just prior to treatment. Such verification reduces respiration induced geometrical uncertainties, enabling safe delivery of 4D radiotherapy such as gated radiotherapy with small margins.

Algorithms↗
PubMed2004

Feasibility study for collecting alcohol and other drug use data among secondary school students: a web-based survey approach.

This study examined the feasibility of using a Web-based survey to collect alcohol and other drug use data from secondary school students in an urban school district in the Midwest. A Web-based survey was self-administered by a random sample of 6th through 11th grade students in the spring of 2002. The final sample consisted of 1,536 secondary school students (781 women and 755 men). The sample was 57% White, 40% African American, and 3% from other racial and ethnic groups. Several indicators of data quality were examined including response rate, absenteeism, refusals, substantive data, and data processing time. The study achieved a response rate of 89.1%. The results of the present study provide evidence that a Web-based survey can be successfully implemented in an economically and racially diverse urban sample of secondary students. While researchers conducting survey research within secondary schools should consider using Web-based survey approaches, additional research is needed to compare Web-based surveys to more traditional approaches to collecting data.

Adolescent↗
PubMed1994

Systemic therapy of cutaneous T-cell lymphomas (mycosis fungoides and the Sézary syndrome).

OBJECTIVE: To review recent studies of systemic therapy for mycosis fungoides and the Sézary syndrome (cutaneous T-cell lymphomas). DATA SOURCES: English-language articles indexed in MEDLINE from 1988 through 1994. STUDY SELECTION: All therapeutic studies were selected. DATA EXTRACTION: The data were abstracted without judgments on response criteria or patient numbers. Data quality and validity were assessed by independent author reviews. DATA SYNTHESIS: No systemic therapy cures patients with cutaneous T-cell lymphomas. Single and combined chemotherapeutic agents produce high response rates. Whether any of these is preferred is not established. A randomized trial comparing combination chemotherapy plus radiation therapy with topical therapy showed no survival benefit for the combination. Several adenosine analogs and retinoids were active, but their optimal use is uncertain. Interferons are as active as chemotherapeutic agents and may be less toxic. Interferon combined with psoralen plus ultraviolet A light therapy produces high complete response rates and long-lasting remissions. Combinations with other systemic therapies do not increase response rates. Photopheresis therapy should be regarded as experimental. Promising preliminary results were seen with interleukin-2 fusion toxins and several antibody conjugates. CONCLUSIONS: Systemic therapy should be considered effective and palliative. The principles of treating all low-grade lymphomas can be applied. Randomized trials are needed to evaluate new agents (such as a comparison of psoralen plus ultraviolet light with or without interferon), and large phase II trials are needed for new agents such as photopheresis, interleukin-2 fusion toxin, temozolomide, and others.

Combined Modality Therapy↗