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PubMed1983

Effect of variations in room temperature on measured values of blood gas quality-control materials.

We compared four commercial quality-control materials equilibrated in sealed ampoules at 21 or 26 degrees C in three models of blood gas machines and found po2 differences of about 13.3 Pa (10 mmHg) for an aqueous mixture with hemoglobin; about 6.7 Pa (5 mmHg) for two aqueous buffers without hemoglobin, and none for a fluorocarbon-containing emulsion. Differences for pco2 and pH were small but statistically significant. Variability within machines for pco2, po2, and pH was small but differences among machines were large, especially for po2. These results emphasize that aqueous solutions and hemoglobin-containing mixtures used for proficiency testing and quality control should be equilibrated at the temperature recommended by the manufacturer, opened, and sampled promptly.

Blood Gas Analysis↗

PubMed2005

Simpleaffy: a BioConductor package for Affymetrix Quality Control and data analysis.

UNLABELLED: Quality Control is a fundamental aspect of successful microarray data analysis. Simpleaffy is a BioConductor package that provides access to a variety of QC metrics for assessing the quality of RNA samples and of the intermediate stages of sample preparation and hybridization. Simpleaffy also offers fast implementations of popular algorithms for generating expression summaries and detection calls. AVAILABILITY: Simpleaffy can be downloaded from http://www.bioconductor.org. SUPPLEMENTARY INFORMATION: Additional information can be found on the supplementary website located at http://bioinformatics.picr.man.ac.uk.

Computational Biology↗

PubMed1975

A proposed blind routine quality control system for multichannel analyzers.

A blind quality control system using a special type of commercial reference serum is described. As packaged, the product contains six pools of analyzed reference sera with vials identified by coded numbers. The test constituents in the pools cover the range of multichannel analyzers in a random manner, i.e., each pool contains constituents in the low, normal and elevated ranges. As specific pools are not identified, and the analyst is unaware of the expected values for each constituent, results collected for quality control purposes are unbiased, i.e., free of conscious or unconscious editing. Data analysis in the proposed system is by least-squares technics. During an eight-week period, performance was studied using the standard error of the estimate to evaluate precision and the slope of the regression line to evaluate accuracy on the SMA and Mark X instruments. As an empirical comparison, the data are expressed as relative errors and precision and accuracy of analyzer performance evaluated as mean and standard deviation. The proposed regression analysis-based technic has the advantage of simultaneously evaluating linearity, as well as checking accuracy and precision over the total dynamic range of the instrument by use of a series of related serum pools.

Alkaline Phosphatase↗

PubMed1992

Comparing the power of quality-control rules to detect persistent systematic error.

A simulation approach that allows direct estimation of the power of a quality-control rule to detect error that persists until detection is used to compare and evaluate the error detection capabilities of a group of quality-control rules. Two persistent error situations are considered: a constant shift and a linear trend in the quality-control mean. A recently proposed "moving slope" quality-control test for the detection of linear trends is shown to have poor error detection characteristics. A multimean quality-control rule is introduced to illustrate the strategy underlying multirule procedures, which is to increase power without sacrificing response rate. This strategy is shown to provide superior error detection capability when compared with other rules evaluated under both error situations.

Chemistry, Clinical↗

PubMed1981

Analysis of urinary calculi; a quality control programme.

Results of the first Nordic quality control programme on urinary calculi are described. The programme included nine specimens, nine components and 57 laboratories participated. Most of the specimens were mixtures of selected human calculi. Of the laboratories, 67% used a binary scale for the results("qualitative"); 80% of the laboratories were unable to carry out the analysis on 10 mg material or less. For most components false positive results were rare. Oxalate and calcium (II), however, were exceptions. Results on "mixed stones" were unsatisfactory; frequently 20% of the results were wrong. The fraction of false negative results is 0.10 for cystine and urate, and is generally higher for other components. No difference between the reliability of infrared spectrometry and of wet chemistry is observed. An ordinary internal quality control scheme is suggested to facilitate improvements of the routine analytical performance. Some ideas of the analytical strategy are discussed. The drawbacks of results from a binary scale are stressed, and it is suggested that the examination of urinary calculi be carried out using techniques which give results on continuous scales. At the same time the number of components for analysis in the routine programme may be reduced.

Ammonia↗

PubMed2003

Quality control in urodynamics: a review of urodynamic traces from one centre.

OBJECTIVE: To investigate quality control in our unit and to enable other units to compare their results, as experience from central reviews of urodynamic traces for multicentre trials has suggested that poor quality control is common. PATIENTS AND METHODS: All consecutive male urodynamic tests conducted over 1 year were reviewed. A list of criteria to assess the quality of the records was devised, based upon International Continence Society guidelines on "good urodynamic practice", and on other sources. Eligible traces were analysed for aspects of quality control, e.g. baseline pressures and coughs to test pressure transmission. The data were analysed to establish how often quality criteria were met, and identify areas for improvement. RESULTS: In 100 eligible traces, the baseline detrusor pressure was 0-10 cmH2O in 86, and - 5 to +10 cmH2O in 94%. Baseline intravesical and abdominal pressure were 30-50 cmH2O in 68% and 73% of cases, respectively. Coughs were present before filling in 94%, during filling in 95%, before voiding in 72% and after voiding in 87% of cases. The cough-test frequency was sufficient in 30% of traces. In 11 the intravesical pressure line fell out during voiding. CONCLUSION: Most of the traces assessed met the quality criteria defined, but significant defects were not uncommon. Some of the problems identified suggest areas of urodynamic technique which should be studied in more detail. We intend to modify our quality control practices, and hope to show an improvement on re-audit. We hope that other urodynamic departments will be encouraged to review their practice, and we aim to improve our results.

Adult↗

PubMed2002

Surgical quality control in gastric cancer trials.

Quality control in prospective randomized surgical trials of gastric cancer treatment is reviewed. Progress and innovations in this area are described. Methodologic suggestions for future trials are made.

Gastrectomy↗

PubMed2003

[Study on methods and requirements for quality control of recombinant human tumor necrosis factor receptor Fc fusion protein].

AIM: To establish methods and requirements for quality control of recombinant human tumor necrosis factor receptor Fc fusion protein (rhTNFR-Fc). METHODS: Biological potency of rhTNFR-Fc was determined by neutralizing the bioactivity of TNF-alpha. rhTNFR-Fc samples were reduced by beta-mercaptoethanol and the peptide map was performed by tryptic digestion. Residual protein A and the host cell protein content were detected by ELISA. Anti-TNFR and anti-Fc antibodies were used in ELISA for detection of the rhTNFR-Fc content. RESULTS: The quality control methods, such as bioassay, peptide map, residual protein A detection, were established and used for quality control of rhTNFR-Fc. The unit of rhTNFR-Fc (AU) was defined according to the international unit of TNF-alpha. The specific activity was up to 8 x 10(4) AU.mg-1. The requirements for quality control of rhTNFR-Fc were established. CONCLUSION: The methods and requirement were used for quality control of rhTNFR-Fc products.

Animals↗

PubMed1989

In-hospital bedside blood glucose monitoring: the importance of a quality control program.

This study examined the adequacy of a quality control program to assure accuracy of blood glucose monitoring performed at the bedside by nurses in a general pediatric hospital. A standard quality control program during which all nurses received inservice training and demonstrated proficiency resulted in accuracies (percentage of values within 15% of the laboratory) of only 68.6% and 69.2% over two successive 3-month periods. A standardized refresher course did not improve accuracy. Expansion of the program to include identification and reinstruction of individual nurses who had more than 20% of their blood glucose measurements more than 10% off the laboratory value or any one value more than 40% off the laboratory during the previous quarter resulted in improved accuracies (83%, 78%, and 91%) over three successive 3-month periods. These findings indicate that a systemic quality control program including individual monitoring and remedial retraining is required to improve the long-term accuracy of bedside blood glucose monitoring by nurses in a general pediatric hospital.

Blood Glucose Self-Monitoring↗

PubMed1976

[Quality control of coagulation tests (author's transl)].

The results of quality control of coagulation tests from intralaboratory control programmes are reported and compared with interlaboratory surveys. The test programme includes the following assays: the thromboplastin time (Quick), the partial thromboplastin time and the thrombotest. It can be seen from the results of the thromboplastin time that reliable figures were obtained from intralaboratory quality control examinations only (CV=7% to 13%). In comparison to these results great differences were found in interlaboratory surveys (CV=15% to 30%). The result of interlaboratory surveys of the thrombotest demonstrated a CV of 15% to 20%. The intralaboratory quality control of the partial thromboplastin time showed satisfactory reliability (CV=7.4%). Satisfactory conformity of results was obtained between different laboratories only by using common reagents (CV=8.7%). Possible factors responsible for deviations in laboratory examinations are discussed and proposals for improvement in the realibility of coagulation tests are made.

Blood Coagulation Tests↗

PubMed1997

Quality control of biomarker measurement in epidemiology.

The throughput and complexity of a biomarker assay will determine the amount of effort that can be expended on quality control and assurance. Clinical chemistry quality control procedures can be readily applied to simpler chemical analysis such as blood lead and cholesterol, but even complex cell-based biomarker techniques such as HPRT mutation analysis and cytogenetics benefit from a formal quality control approach. Collaborative interlaboratory exercises are essential, especially when no certified reference material is available, and these can play a central role in the control of laboratory drift. Recommendations are made for the quality control of biomarker measurement based on clinical chemistry techniques. These include recommendations for coding samples so that the laboratory scientist is unaware of exposure status and for the use of formal laboratory protocols.

Biomarkers, Tumor↗

PubMed1982

Quality control in the pulmonary function laboratory.

The addition of computers to pulmonary function laboratories has reduced quality-control problems. After standards for a test have been selected, the computer can enforce adherence to them. The computer can be programmed to perform periodic calibration checks and other self-diagnostic procedures to ensure that instrumentation and human errors have not gone undetected. The computer can be used to verify that reference values are within acceptable limits and that results for a particular patient are at least internally consistent. The computer greatly reduces the number of measurements and calculations that must be done by hand and therefore improves laboratory efficiency and reduces the probability of human error. Quality-control samples can be processed more frequently with the use of a computer because this task consumes less time than when done by laboratory personnel. Some disadvantages of quality control that have appeared since the introduction of the computer are the potential for undetected failure of computer hardware and software, a risk that has increased with the increase in software complexity, and the potential for the loss of large amounts of information because of its being stored on a single digital medium. To effect quality control in the pulmonary function laboratory one should (1) ensure that procedures and software conform to standards, (2) follow routine calibration-check procedures, (3) check test results for internal consistency and for consistency with other test results, (4) conduct periodic testing of a quality-control subject or reference sample, (5) continually evaluate software performance, (6) carefully evaluate changes in instrumentation and software, and (7) maintain duplicate copies of data on different types of mass storage media.

Calibration↗

PubMed2005

Frequently asked questions at the Quality Control Centre Switzerland (CSCQ).

The Quality Control Centre Switzerland (CSCQ) is one of two National EQAS organisers for the medical laboratory. Frequently asked questions at the CSCQ from two time periods have been analysed and compared. They form one of the sources for continuous improvement. It turns out that question frequency per se is not a criterion for the intended purpose. Well formulated single questions or remarks from different sources, together with the institutionalized practice of process evaluation, can lead to specific measures.

Information Dissemination↗

PubMed2005

Net analyte signal based statistical quality control.

Net analyte signal statistical quality control (NAS-SQC) is a new methodology to perform multivariate product quality monitoring based on the net analyte signal approach. The main advantage of NAS-SQC is that the systematic variation in the product due to the analyte (or property) of interest is separated from the remaining systematic variation due to all other compounds in the matrix. This enhances the ability to flag products out of statistical control. Using control charts, the analyte content, variation of other compounds, and residual variation can be monitored. As an example, NAS-SQC is used to appreciate the control content uniformity of a commercially available pharmaceutical tablet product measured with near-infrared spectroscopy. Using the NAS chart, the active pharmaceutical ingredient (API) content is easily monitored for new tablets. However, since quality is a multivariate property, other quality parameters of the tablets are also monitored simultaneously. It will be demonstrated that, besides the API content, the water content of the tablets as well as the homogeneity of the other compounds is monitored.

Chemistry Techniques, Analytical↗

PubMed1996

Initial results of Central European Immunophenotyping Quality Control Program (CEQUAL).

The new Quality Control Program in Immunophenotyping for Central Europe (CEQUAL) was created in 1993. Its first formal send-around proficiency exercise, consisting of a stained stabilised preparation of leukocytes, took place in November 1993. Forty-one laboratories from Slovakia, Poland, Hungary, and the Czech Republic participated. Eighty-three percent of member laboratories returned results and list mode files. The results for each cell population were evaluated for central tendencies, variability, and overall distribution patterns. Extreme outliers were identified and list mode files reviewed for clues to the aberrerant values. When found these reasons were communicated back to member labs. When extreme outlier values were removed, all coefficient of variations (CVs) for lymphocyte populations were below 10%, except for NK cells, which had a CV of 14.8%. In future send-arounds, unstained and pathologic specimens will be used. This CEQUAL program is the first to function on such a broad international basis.

CD4-CD8 Ratio↗

PubMed1980

Quality control of agar diffusion susceptibility tests. Data from the Quality Assurance Service Microbiology Program of the College of American Pathologists.

From 1974 through December 1978, over 180 laboratories participated in the Microbiology Program of the College of American Pathologists Quality Assurance Service (QAS), submitting a total of 2,372,000 individual antibiotic determinations on three quality control reference strains. Of these determinations, 89.5% were obtained by the standard Bauer-Kirby method; 8.4% by the agar overlay modification of Barry and associates. Standard statistical analysis of data obtained using the agar overlay modification has been reported for each antimicrobic/reference strain combination. Comparisons have been made between the QAS data and those data obtained in earlier collaborative studies, which currently serve as precision and accuracy control limits. In many cases QAS data exceed the existing control limits.

Anti-Bacterial Agents↗

PubMed2000

Degradation of unassembled Vph1p reveals novel aspects of the yeast ER quality control system.

The endoplasmic reticulum quality control (ERQC) system retains and degrades soluble and membrane proteins that misfold or fail to assemble. Vph1p is the 100 kDa membrane subunit of the yeast Saccharomyces cerevisiae V-ATPase, which together with other subunits, assembles into the V-ATPase in the ER, requiring the ER resident protein Vma22p. In vma22Delta cells, Vph1p remains an integral membrane protein with wild-type topology in the ER membrane before undergoing a rapid and concerted degradation requiring neither vacuolar proteases nor transport to the Golgi. Failure to assemble targets Vph1p for degradation in a process involving ubiquitylation, the proteasome and cytosolic but not ER lumenal chaperones. Vph1p appears to possess the traits of a 'classical' ERQC substrate, yet novel characteristics are involved in its degradation: (i) UBC genes other than UBC6 and UBC7 are involved and (ii) components of the ERQC system identified to date (Der1p, Hrd1p/Der3p and Hrd3p) are not required. These data suggest that other ERQC components must exist to effect the degradation of Vph1p, perhaps comprising an alternative pathway.

Cytosol↗

PubMed1983

Central laboratory quality control in the National Cooperative Gallstone Study.

This article presents the rationale, selection, operation, and quality control of the Central Serum and Central Bile Laboratories utilized by the National Cooperative Gallstone Study. The external quality control protocols were designed to monitor long-term stability of the analytical procedures and to measure the precision of the measurements as affected by the collection, labelling, storage, shipping, and laboratory methods. For both laboratories, the assessment of long-term stability by pool standards failed to produce the data necessary to come to relevant conclusions. Several of the problems involved, however, did lead to protocol changes that increased the reliability of the laboratory data. The use of duplicate measurements to monitor precision was more successful and demonstrated acceptable performance of these systems. This article describes the external quality control surveillance procedures employed in the NCGS, their strengths and weaknesses, statistical methods for the analysis of such quality control programs, and the implications for the final statistical analyses of the clinical trial patient data.

Bile↗