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At least 1,153 records · Page 64Linked to original sources
PubMed2002

Longitudinal quality control methodology for the quantitative ultrasound Achilles+ in clinical trial settings.

Appropriate quality assurance (QA) and quality control (QC) procedures have been well developed and validated for dual X-ray absorptiometry (DXA), and are widely applied in multicenter clinical trials to monitor device stability used to check the treatment effects on bone mineral density. This is not yet the case for quantitative ultrasound (QUS) technology, for which no QC approaches have yet been fully tested. The first Achilles (GE-Lunar Corporation, Madison, WI, USA) has been on the market for 10 years (1991). The goal of this study was to develop the QC methodology for the QUS Achilles+ device using its past/current experience (log and maintenance files.) as well as by integrating the progress made over the last years in the ultrasound domain so as to better understand the influence of temperature on ultrasound parameters. Because of the lack of confidence in the external black rubber phantom used in daily QC with the Achilles+, to monitor the device stability, we selected several QC parameters known to be influenced by potential malfunctions as experienced by the maintenance department of GE-Lunar company as well as the physical approach. These are phantom temperature-adjusted speed of sound (PSOS-TC) and broadband ultrasound attenuation (PBUA-TC), water speed of sound error (WSE), water spectrum slope (WSS) and water gain (WG). We used four Achilles+ devices perfectly stable during their entire QC range, to calculate the optimum thresholds (based mostly on 95% confidence interval) for each of these parameters as well as the precision for the in vitro SOS and BUA. An additional not fully stable Achilles device has been used to run a QC procedure example. The precision expressed as the CV was 0.22% and 0.65% for the PSOS-TC and PBUA-TC, respectively. The alarm thresholds used for QC process are +/- 0.6%, +/- 1.9%, +/- 6.8 m/s, +/- 5.3% and +/- 7.3% for the PSOS-TC, PBUA-TC, WSE, WSS and WG, respectively. Applying a logical approach on the impact of each parameter on each other as well as their respective reactivity to malfunctions, we build a QC process flowchart meant to detect real malfunction in the daily QC. We found that in case of real malfunctions, the in vivo SOS should be decreased by 1.33 m/s for each 1 m/s increase in WSE. Unfortunately, in vivo BUA can not be adjusted when real malfunction occurs. Nevertheless, the BUA can be qualified as bad quality data and excluded from the medical interpretation. Using the currently available phantom and parameters, the best possible QC procedures to detect long-term drift in the daily QC of the Achilles+ was developed. To fully validate our approach and gain confidence in the defined limits it is our plan to apply this QC processing to a higher number of QUS devices.

Bone and Bones↗
PubMed1986

Quality control of technetium-99m DTPA: correlation of analytic tests with in vivo protein binding in man.

When [99mTc]DTPA is administered, a small fraction of the activity (presumably an impurity) is bound to plasma proteins. This causes an error in the calculation of glomerular filtration rate from plasma clearance. This paper presents two methods of laboratory quality control for measuring the fraction that binds to plasma proteins. One method involves in vitro binding to human serum albumin followed by gel filtration. The other method involves descending paper chromatography on wet pre-equilibrated anion exchange paper. In a series of 80 patients, correlation was demonstrated between laboratory characteristics and actual clinical performance of the [99mTc]DTPA preparation. Both laboratory methods appear suitable for routine quality control.

Blood Proteins↗
PubMed2005

Quality control for histological grading in breast cancer: an Italian experience.

Although the diagnostic criteria for histological grading in breast cancer have been improved by the introduction of the Nottingham/Tenovus classification, good results in terms of reproducibility are hard to obtain. The objective of this study was to validate a methodological protocol for external quality control. We assessed the intra- and interlaboratory reproducibility for grading score and its components. Our findings revealed a less than optimal level of agreement for both intra-observer and interobserver reproducibility. Each grading class contributed in a different way to the reproducibility and class G2 provided the poorest contribution to the observed agreement. Nuclear pleomorphism appeared to be the least reproducible, followed by mitotic count and tubule formation. In conclusion, our results suggest the need for quality control programs that should be conceived as a dynamic feedback process to better understand the reasons for some unsatisfactory performances and to implement the necessary corrective actions.

Breast Neoplasms↗
PubMed2000

Reliability of malaria microscopy in epidemiological studies: results of quality control.

To assess the interrater reproducibility of malaria microscopy in epidemiological studies, 711 thick blood films from population-based surveys were randomly selected and reread by 4 experienced microscopists. Sample estimates of the prevalence of P. falciparum infection, geometric mean parasite density and the proportion of samples above various parasite density cut-off levels were almost identical in the routine and quality control readings. Differences were, however, encountered in the sample estimates for gametocyte ratio, proportion of mixed infection and average density index. In all three cases the quality control result was significantly higher than the routine evaluation. On the level of the individual slide there was good interrater agreement for the presence of P. falciparum infections (Kappa index kappa = 0.79) which was even better when parasite densities between 4 and 100/microl were excluded (kappa = 0.94). With respect to the assessment of parasite density, a high level of disagreement was found. While the mean difference between the two readings was not different from 0, the second reading was between 0.12 and 10 times that of the first. However, the level of disagreement significantly fell with increasing parasite densities. Thus malaria microscopy is very reliable for the estimation of parasite ratios and geometric mean parasite densities within and between studies as long as the same methodology is used, but tends to underestimate the gametocyte ratio and proportion of mixed infections. Care must be taken, however, when individual parasite density is related to other explanatory variables, due to the high degree of variability in the parasite enumeration.

Animals↗
PubMed1985

China's experiences in the quality control of its 1982 population census.

The author reports on experiences with China's 1982 census, which covered approximately one billion people and 19 census items. It is noted that "the postenumeration sample survey indicates that the quality of the census enumeration is: 0.071% of overcounts and 0.056% of undercounts. The paper presents principles governing quality control in the population census and explains a series of quality control procedures adopted to reduce possible errors originating in census planning, enumeration and data processing."

Asia↗
PubMedDate not supplied

Genetic quality control of laboratory animals used in aging studies.

Laboratory rodents provide a useful model for aging processes in humans. Various genetic "types" of stock are available, including outbred stocks and inbred strains and their derivatives. Inbred strains, which can be regarded as clones of genetically identical individuals, provide a powerful research tool for studies in many disciplines, including gerontology. However, some form of genetic quality control is essential to ensure that the strains are authentic. Single gene polymorphisms, particularly those detected by electrophoresis and immunological methods, provide a powerful tool for such quality control, though these methods are expensive and require considerable expertise. Methods based on several loci studied simultaneously include skin grafting and polyvalent alloantisera. These methods are often quick and technically relatively easy, but are less flexible than the single locus methods. Methods based on DNA restriction fragment length polymorphisms (RFLPs) fall into both categories depending on whether a single locus or a multilocus probe, such as the fingerprinting probes, is used. These DNA-based methods have many advantages, and are likely to be the methods of choice in the future.

Aging↗
PubMed1996

Analytical methods for the characterization and quality control of pharmaceutical peptides and proteins, using erythropoietin as an example.

In the last twenty years many peptides and proteins were introduced to the market for pharmaceutical use. The high complexity of the biomacromolecules requires the use not only of physicochemical methodologies but also of immunochemical and biological techniques for the characterization and quality control of these substances. Characterization of the active conformation and post-translational modifications is important for the understanding of the in vivo activity of peptides and proteins. Among other spectroscopic techniques circular dichroism has become a helpful tool for evaluating the secondary and tertiary structure of proteins and peptides. A combination of several analytical methods is necessary for a comprehensive characterization of the substance under investigation and for an appropriate quality control of the product concerning identity, purity and potency. Suitable analytical methodologies are discussed using erythropoietin as an example.

Amino Acid Sequence↗
PubMed2004

Utilization of a labeled tracking oligonucleotide for visualization and quality control of spotted 70-mer arrays.

BACKGROUND: Spotted 70-mer oligonucleotide arrays offer potentially greater specificity and an alternative to expensive cDNA library maintenance and amplification. Since microarray fabrication is a considerable source of data variance, we previously directly tagged cDNA probes with a third fluorophore for prehybridization quality control. Fluorescently modifying oligonucleotide sets is cost prohibitive, therefore, a co-spotted Staphylococcus aureus-specific fluorescein-labeled "tracking" oligonucleotide is described to monitor fabrication variables of a Mycobacterium tuberculosis oligonucleotide microarray. RESULTS: Significantly (p < 0.01) improved DNA retention was achieved printing in 15% DMSO/1.5 M betaine compared to the vendor recommended buffers. Introduction of tracking oligonucleotide did not effect hybridization efficiency or introduce ratio measurement bias in hybridizations between M. tuberculosis H37Rv and M. tuberculosis mprA. Linearity between the mean log Cy3/Cy5 ratios of genes differentially expressed from arrays either possessing or lacking the tracking oligonucleotide was observed (R2 = 0.90, p < 0.05) and there were no significant differences in Pearson's correlation coefficients of ratio data between replicates possessing (0.72 +/- 0.07), replicates lacking (0.74 +/- 0.10), or replicates with and without (0.70 +/- 0.04) the tracking oligonucleotide. ANOVA analysis confirmed the tracking oligonucleotide introduced no bias. Titrating target-specific oligonucleotide (40 microM to 0.78 microM) in the presence of 0.5 microM tracking oligonucleotide, revealed a fluorescein fluorescence inversely related to target-specific oligonucleotide molarity, making tracking oligonucleotide signal useful for quality control measurements and differentiating false negatives (synthesis failures and mechanical misses) from true negatives (no gene expression). CONCLUSIONS: This novel approach enables prehybridization array visualization for spotted oligonucleotide arrays and sets the stage for more sophisticated slide qualification and data filtering applications.

Analysis of Variance↗
PubMed1987

[Comparison between phantoms for quality control in xeromammography].

An indicator of operating technique (phantom) is very useful for quality control in diagnostic radiology. We tested experimentally that the "Random Phantom" is the most suitable between those commercially available for xeromammography. In fact this indicator points out image quality alterations caused even by very small variations of the physical parameters affecting image quality. We did not test the phantoms for mammographic technique but we believe that the "Random" is the most suitable in this field too.

Humans↗
PubMed1998

Statistical quality control methods in infection control and hospital epidemiology, Part II: Chart use, statistical properties, and research issues.

This is the second in a two-part series discussing and illustrating the application of statistical process control (SPC) in hospital epidemiology. The basic philosophical and theoretical foundations of statistical quality control and their relation to epidemiology are emphasized in order to expand the mutual understanding and cross-fertilization between these two disciplines. Part I provided an overview of the philosophy and general approach of SPC, illustrated common types of control charts, and provided references for further information or statistical formulae. Part II now discusses alternate possible SPC approaches, statistical properties of control charts, chart-design issues and optimal control limit widths, some common misunderstandings, and more advanced issues. The focus of both articles is mostly nonmathematical, emphasizing important concepts and practical examples rather than academic theory and exhaustive calculations.

Data Display↗
PubMed2004

The Swedish National Programme for Quality Control of Secondary Prevention of Coronary Artery Disease--results after one year.

BACKGROUND: Guidelines for the prevention of coronary artery disease (CAD) have been developed both in Europe and in the USA. However, several surveys have shown that these guidelines are poorly implemented in clinical practice. DESIGN/METHODS: The Swedish Quality Control Programme on Secondary Prevention of CAD includes patients after myocardial infarction, or having undergone coronary artery surgery or percutaneous coronary intervention. Fifty of Sweden's 79 hospital districts are currently participating. Patients are asked to send report-cards regarding risk factor management to a central registry after discharge from hospital, at a 3-6 month visit and then yearly for 5 years. RESULTS: Results based on data from 1 year after the index event show that a majority of patients reach targets for serum cholesterol (70%), and low-density lipoprotein (LDL)-cholesterol (71%). Mean value for total cholesterol is 4.6 (+/-SD 0.9) mmol/l, LDL-cholesterol 2.7 (+/-SD 0.8) mmol/l. Blood pressure targets are less often achieved, with 58% reaching the European Society of Cardiology target for systolic (<140 mmHg) and 81% for diastolic (<90 mmHg) blood pressure. A large proportion of patients are prescribed preventive drugs: aspirin (96%), beta-blockers (78%) and lipid-lowering drugs (83%). CONCLUSIONS: The Swedish Quality Control Programme is one of the first attempts to assess implementation of guidelines on a national level based on patient participation. It is hoped that shared care programmes and increased patient involvement with feedback on achieved treatment goals in relation to guidelines will improve outcomes in patients with CAD.

Adrenergic beta-Antagonists↗
PubMed2026

WxS-QC-a quality control pipeline for human germline short-variant Whole-Genome and Whole-Exome cohorts for population-scale analyses.

SUMMARY: Whole-exome (WES) and whole-genome (WGS) sequencing are rapidly becoming preferred methods for population-scale analysis of the human genetic landscape. However, there are currently no standardized quality control (QC) pipelines for human WES and WGS datasets. In this paper, we present WxS-QC, a powerful, scalable, and convenient pipeline for the QC of human germline short-variant WGS and WES cohorts for population-scale analyses. Our pipeline is suitable for both rare-variant discovery and common-variant association studies. It is based on deeply refactored gnomAD v3 and v4 quality control pipelines, contains several methods we have developed de novo, and is aligned with current best practices in WGS/WES germline cohort QC. We provide all methods in a single codebase, aligned to work together and controlled via a single YAML config, with automatic export of resulting graphs and summary tables, excellent performance and scalability, and comprehensive documentation. The pipeline can run in any UNIX-like environment and can efficiently process cohorts of up to 200&#x2009;000 whole-exome samples, with the potential to handle bigger datasets. AVAILABILITY AND IMPLEMENTATION: The pipeline code is written in Python using the Hail library and is freely available under the BSD-3 license here: https://github.com/wtsi-hgi/wxs-qc. The detailed description of the pipeline is available in the pipeline documentation: https://github.com/wtsi-hgi/wxs-qc/blob/main/README.md. We also provide an open dataset with all required metadata, which is available at https://wxs-qc-data.cog.sanger.ac.uk/wxs-qc_public_dataset_v3.tar. An example of test dataset analysis is available in the supplementary materials.

Humans↗
PubMed1999

Multicenter study of reference stabilized human blood for lymphocyte immunophenotyping quality control in flow cytometry. GEIL.

The development of automated methods and normative rules, as well as the dependence of some therapeutic approaches on lymphocyte subsets counts, has led to the appearance of calibration reagents. Such reagents are expected to perform equally well in very different settings. We developed a multicenter trial to evaluate the performance of a new quality control reagent, i.e., stabilized blood to be used in immunophenotyping laboratories. Aliquots of the same batch of stabilized blood were shipped to 45 French and Belgian laboratories on a Monday and had to be tested for percentages and absolute counts of at least CD3-, CD4-, and CD8-positive lymphocytes on 4 consecutive days. The percentages and absolute counts obtained on each assay were recorded, as well as the type of lysis used, the trademark of reagents, and the brand of flow cytometer. The mean values collected did not differ significantly from those expected by the manufacturer. Absolute counts generated through one-step techniques displayed lower CVs. This new reagent therefore appears to be a robust product, liable to yield consistent results in the array of different conditions represented by routine laboratories, and it could be useful for quality control procedures.

Flow Cytometry↗
PubMed1990

How to use continuous quality improvement theory and statistical quality control tools in a multispecialty clinic.

The management philosophy of continuous quality improvement (CQI) and the tools of statistical quality control (SQC) have the potential for advancing quality management in medicine as they have in industry. The authors report their favorable experience with the approach and explain how to adapt CQI principles and SQC charts and graphs, citing examples from their participation in a quality improvement effort in a multispecialty clinic serving a large hospital. The coupling of statistical techniques with modern approaches to outcome analysis may provide powerful tools not only for quality assurance and assessment but also for technology evaluation and resource allocation.

Data Collection↗
PubMed1980

Quality control in drug measurement.

Therapeutic drug monitoring of serum concentrations has become a rapidly expanding area of clinical pharmacology and is likely to remain an important growth area in the future, despite that the evidence for the efficacy of such monitoring is inconclusive except for a handful of drugs and findings that the reliability of much drug assay work is far from optimal. Nonetheless, in view of the likelihood that the use of routine monitoring will increase, the institution of quality control programs seems not only desirable, but necessary. We describe the design of Bartscontrol (formerly known as St. Bartholomew's Hospital Quality Control Scheme for Antiepileptic Drugs) and discuss the experience of this program. Although the feedback provided to the participants of such a program seems to encourage an overall increase in precision, our findings also indicate that some laboratories perform consistently badly. While the data generally do not reveal that variations in precision are due to analytical method employed, a scheme such as the one described can occasionally make the important finding that a particular technique is inappropriate, as was found for the case of spectrophotometry for phenytoin.

Anticonvulsants↗
PubMedDate not supplied

Operational design and quality control in the CATCH multicenter Trial.

BACKGROUND: The Child and Adolescent Trial for Cardiovascular Health (CATCH) was the first multicenter school-based research study to employ the fundamentals of clinical trials including the standardized protocol and Manuals of Operation, a steering committee for study governance, a distributed data system, an extensive quality control system, and a Data and Safety Monitoring Board. METHOD: CATCH tested the effectiveness of changes in school lunches, physical education, smoking policy, curricula, and family activities. Ninety-six elementary schools in four states were randomized to intervention or control conditions. The baseline cohort comprised 5, 106 ethnically diverse third graders followed through fifth grade. RESULTS: The percentages of calories from fat and saturated fat were reduced significantly more in the intervention school lunches than among the controls. Significant increases in moderate to vigorous activity levels in existing physical education classes were made as well. Changes in self-reported dietary, physical activity, and psychosocial measures were significant. There were no significant differences in the physiological measures. Measurement error was generally low for all physiologic measures except skinfolds, indicating a high level of reliability. Across all sites, the coefficients of variation for lipids, height, and weight were less than 3%, whereas for skinfolds, they were considerably higher, ranging from 6 to 8%. Intraclass correlations for lipid studies were also uniformly high at 0.99. Interobserver agreement scores for SOFIT were greater than 90% for 9 of the 11 activities observed. Data entry error rates were low with less than five errors per 1,000 fields for all forms. CONCLUSIONS: The CATCH results provided more scientific evidence on the importance of schools in the population approach to health promotion. Many of the strategies used in this complex multicenter trial in the areas of design and analysis, measurement, training, data management, and quality control protocols might be appropriate for adoption in other studies.

Adolescent↗
PubMed1997

International quality control of phage typing of Staphylococcus aureus. International Union of Microbial Societies Subcommittee.

A questionnaire was sent to the 48 national typing centres for Staphylococcus aureus and 31 replies were received. Methods of phage typing varied and molecular methods were not universally available, although pulsed-field gel electrophoresis was offered by 13 centres. Results for a quality control phage typing exercise were received from 25 centres. Increased standardisation of methods and definitions are indicated. Differences from the consensus patterns were mainly due to typing at an inappropriate dilution of phage, but five strains caused difficulties in many centres. Overall reproducibility was good. Phage typing remains a cost-effective method for epidemiological studies, particularly on a large scale. The strains selected for the quality control exercise included many strains suitable for controlling molecular methods as well as testing phage typing. Molecular methods help in the validation of the conclusions which may be drawn from phage typing.

Bacterial Proteins↗
PubMed2002

Surgical trials in oncology. the importance of quality control in the TME trial.

Results from randomised trials provide the best scientific evidence of efficacy or inefficacy of the therapy. The evaluation of surgical procedures involves problems in addition to those associated with medical experimentation. Surgery, unlike a pill, is not a standardised, reproducible entity, but a unique product whose details are defined by, for example, the skill of the surgeon. Quality assurance is important for treatment and also for data handling. The different treatments (surgery, pathology, radiotherapy, etc.) should be familiar to all participating physicians prior to the start of the trial. Instructions can be given by means of a well-written protocol, videotapes, workshops and instructors at the dissection table. The data collection and data check should be done by data managers and co-ordinators for the separate disciplines. Errors and missing data should be completed and feedback to the physician is essential. Close contact between an active co-ordinating data centre, including co-ordinators for the separate disciplines, and all participating physicians is essential to conduct a quality controlled multicentre, multidisciplinary trial. Continuous enthusiasm can be maintained by the organisation of regular workshops, distribution of newsletters and trial up-dates at scientific meetings. The efforts from all of the involved co-ordinators, data managers, instructors and physicians have resulted in a very successful trial with rapid accrual, good quality treatments and procedures, good quality data, and a high participation rate among hospitals and patients. Quality control is expensive and labour-intensive, but it is worthwhile.

Colorectal Neoplasms↗