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PubMed1981

Stability of sodium and potassium in lyophilized quality control serum. A study of data from the Quality Assurance Service Program of the College of American Pathologists.

The long-term prereconstitution stability of sodium and potassium in large pools of lyophilized quality control serum used in Regional Quality Control Programs, conducted between 1977 and 1980 is reviewed. In approximately one third of 27 pools studied, minimal but significant increases in sodium concentration were detected, these increases averaged less than 0.50 per year and confirmed our previously reported results from pools analyzed between 1973 and 1976. Results relating to potassium stability have been inconsistent. The previously reported tendency for potassium to increase in some pools was again suggested by data obtained from laboratories using automated flame-emission photometry procedures. This was not confirmed, however, by the data reflecting manual/semi-automated flame-emission photometry procedures or automated electrode methods. It is postulated, that the source of sodium causing the increases in concentration is the glass containers in which control materials are stored between the time of manufacture and reconstitution. Regression analysis against time of monthly interlaboratory means, from participants in Regional Quality Control Programs, is a useful tool for evaluating postmanufacture stability of analytes in pools used for daily internal quality control procedures.

Blood Preservation↗
PubMed2005

Quality control of automatically defined cancer cases by the automated registration system of the Venetian Tumour Registry. Quality control of cancer cases automatically registered.

BACKGROUND: In the Venetian Tumour Registry a substantial quota of cases (55%) is accepted using an algorithm that automatically evaluates diagnostic evidence: this study aims at assessing the reliability of the information produced in this way. METHODS: A reabstraction study was conducted, which put a stratified sample of 1539 automatically accepted cases through a double-blind manual revision. RESULTS: A significantly higher proportion of prevalent cases were found among breast, prostate and larynx cancer cases without microscopic confirmation, while there is a clear strong inverse relationship between the number of concordant diagnostic sources and the proportions of discordant diagnoses: cases based only on a single cytology record are particularly unreliable. A small number of multiple cancers are not detected because of one of the rules applied. CONCLUSION: The overall proportion of incorrect decisions is not high and similar to those reported by other registries, but errors are correlated to the diagnostic evidence pattern. As a further check, we decided to revise clinical cases for the three sites mentioned manually, in order to reduce the numbers proportion of both prevalent cases, and all cytology-based diagnoses, so as to reduce the number of 'false positives'. Coverage of hospital discharge source has been extended in order to decrease the proportion of cases based only on pathology records.

Algorithms↗
PubMed1978

Computers and quality control in nuclear medicine.

The general topic of computers and nuclear medicine quality control may be approached from two main areas; controlling the quality of computerized studies, and computer applications in general nuclear medicine quality control. Overlap occurs when quality control of computer studies is performed by the computer itself. The uses of computers in record-keeping and in quality control of imaging instrumentation and in vitro studies, including radioimmunoassay, are discussed in this review. Aspects of quality control for computerized clinical cardiovascular, cerebral, and renal studies and emission computed tomography are reviewed, including consideration of difficulties and inaccuracies involved in the studies. Any automatic computer analysis program should incorporate adequate checks and error detection protocols and should illustrate results for verification. Current routine quality control procedures using the computer unfortunately are few. Quality control criteria are needed for camera/computer systems in high count rate clinical applications, and increasing emphasis should be aimed at quality control of those computerized dynamic and function studies in current clinical use. The computer has a valuable potential for nuclear medicine quality control. In vitro and computerized in vivo studies can be analyzed by readily available statistical programs, and variances can be monitored continuously. Computers can calibrate and monitor instrument performance regularly, and can handle managerial and clerical duties such as bookkeeping.

Cardiovascular Diseases↗
PubMed1988

Multiprogram characterization of laboratory bias, precision, and total error. Proposal for improved assessment with shared external and expanded internal (regional) quality control pools.

We establish that, for the analytes aspartate aminotransferase, glucose, phosphorus, and potassium, there is significant correlation between laboratory performance as determined by College of American Pathologists-sponsored external (Surveys) and expanded internal (regional) quality control (Quality Assurance Service) programs. However, relatively low parametric and nonparametric correlation coefficients and significant departure of linear regression slopes from unity reflect major differences in the calculated parameters of absolute bias, precision, and total error obtained through internal and external quality control. Significantly better performance in both Surveys and the Quality Assurance Service was documented for laboratories participating in the College of American Pathologists Laboratory Accreditation Program. Multiple descriptors of laboratory quality, as indicated here, are superior in describing laboratory performance to proficiency testing alone. As a bridge between external and internal quality control, shared pools of quality control materials are described for use as unknown Survey challenges and subsequent distribution for regional quality control. Such programs, which can be configured to serve thousands of laboratories, could offer cost savings, better quality assurance, and improved characterization of laboratory performance by minimizing interprogram differences in control matrix and method classification and providing greater reliability of target values.

Academies and Institutes↗
PubMed1995

Statistical and genetic aspects of quality control for DNA identification.

Quality control for likelihood ratio (LR) tests on restriction fragment length polymorphisms (RFLPs) and polymerase chain reaction (PCR) markers is provided by the 4N6 program. Examples are given for test of exclusion, coincidence, and kinship that should be used routinely in validation of DNA profiling. They confirm that "in a knowledgeable court DNA profiling is no longer exposed to risk of illogical presentation, blind acceptance or arbitrary rejection" (N. E. Morton, Eur. J. Hum. Genet. 1993, 1, 172-179). However, they remain to be implemented in national systems of quality control. There can be no effective quality control until attempts to fudge gene frequencies in order to retain the Hardy-Weinberg assumption (recommended by the National Research Council) ar abandoned in favour of the population genetic approach that takes gene frequencies from a real population and uses kinship to express genotype probabilities. Since an expert witness cannot know the identity of the culprit, he is obliged to consider multiple hypothesis without usurping the prerogative of the court to favour one of them on the basis of other evidence. It remains to be seen whether the new NRC Committee (and more importantly the international community of forensic scientists) will adopt this fundamental principle, which is especially important in populations like India with preferential endogamy and consanguineous marriage. Alternative procedures and the causes, effects, and remedies of four types of error are also considered.

DNA Fingerprinting↗
PubMedDate not supplied

[Implementation of a quality control system in transfusion practice].

Quality assurance and improving systems, standardization of all transfusion procedures as well as quality control and standardization of prepared blood products are necessary elements for work of transfusion centers in the future. Requirements for blood and/or blood products for therapy are: safety, adequate concentration of all active components needed, and treatment efficacy. To satisfy these requirements, we decided to adjust the work process of transfusion service to requirements of ISO 9001 standard series. To achieve this aim, quality control system documentation is created. Creation of quality control system documentation is one of the most difficult and most comprehensive parts the quality control system implementation process. The quality policy is adopted, whereas the basic procedures for blood products quality control, which are the subject of this paper, are created.

Blood Transfusion↗
PubMed1994

Inclusion of a sensitivity control to add a quality-control parameter and improve reproducibility in BCR, immunoglobulin, and T-cell receptor gene-rearrangement studies.

Molecular analyses to determine clonality of T and B cells in malignant lymphoma and leukemia and to detect the (9;22) translocation in chronic myelogenous leukemia are commonly used in clinical molecular biology laboratories. We describe the inclusion of a sensitivity control in each of these assays derived from DNA of well-characterized cell lines. The inclusion of such a sample adds an important quality-control parameter to ensure assay-to-assay reproducibility and to satisfy accreditation and regulatory requirements.

Blotting, Southern↗
PubMed1980

Cumulative sum control charts for admixture quality control.

The use of cumulative sum control charts as a means of monitoring the sterility of i.v. admixtures produced by a centralized service is discussed. To create a sum control chart, acceptable and rejectable quality levels must be determined. Frequency of sampling will responsiveness and can be varied to affect the length of time necessary to detect an unacceptable shift in product quality. Cumulative sum control charts allow monitoring to be carried out on a cost versus benefit basis, and can be used to provide a basis for action on production of existing product and to maintain or improve product quality in the future.

Drug Combinations↗
PubMed2001

Quality control by cocaine users: underdeveloped harm reduction strategies.

The use of any drug involves both values and rules of conduct (social sanctions) and patterns of behavior (social rituals). Based on an ethnographic study (1996-1999) among 111 cocaine users from the metropolitan area of Antwerp (Belgium), the self-regulatory mechanisms surrounding the methods of controlling the quality of a drug are described. Users' perceptions of reliable and unreliable sources of cocaine, quality and adulteration of cocaine and quality control techniques are confronted with objective information. It is argued that these informal control mechanisms may be crucial factors in the controlled use of any intoxicant, but myths are an important ingredient of the observed rituals, which indicates that knowledge about certain drugs and the best ways to use them in a safe way is still underdeveloped. Users are left to their own folk-experimental devices for testing tools or techniques, and many aspects of the natural processes of social learning are generally not based on objective information. Future harm reduction interventions should therefore also stimulate the development and dissemination of effective informal control mechanisms among illicit drug users.

Amphetamines↗
PubMed1995

Image quality and dose in lumbar spine examinations: results of a 5 year quality control programme following the European quality criteria trial.

The large dose values found for lumbar spine examinations in a centre participating in the European quality criteria trial have been investigated within a 5 year quality control programme. Actions focused mainly on optimizing the focus-to-film distance, tube potential (kV), film optical density and X-ray beam filtration. These actions lead to overall dose reductions of up to 75% in lumbo-sacral joint examinations and prove the need for a regular survey of patient skin doses.

Humans↗
PubMed1981

Proposals and current practices in quality control.

The current status of quality control in clinical laboratories is discussed, and selected new techniques for quality control and presented from the literature of the last six years. The concept of quality control is broadened beyond the running of control materials for validation of test runs. Methods for recognition, identification, and reduction of both process error are presented. Examples are presented of improvements utilizing graphic techniques, manipulation of control and check sample sera, statistical techniques for interpretation of trends, quality control action rules for the detection of out-of-control situations and method evaluation.

Analysis of Variance↗
PubMed1991

A quality-control program for colposcopic practice.

Quality control is accepted as an integral part of the cytology laboratory's activities. However, provision of similar safeguards for colposcopic practice in assessing patients with abnormal cervical cytology has been an elusive problem. This report describes the quality-control program for colposcopy that is used province-wide in British Columbia for 21 hospital-based clinics staffed by 35 colposcopists. Copies of the results of all colposcopic examinations performed are sent to the Central Cytology Laboratory where the program is coordinated and the data are collated, analyzed, and evaluated. These data are used to set standards against which each colposcopist's performance and activity can be measured. One of the quality-control indicators used is a comparison between the colposcopic impression of the lesion and the corresponding direct biopsy diagnosis. Correlation within one histologic degree occurred in 86% of patients examined; this information was used to set a performance standard of 80% as the quality-control index for this particular indicator. Three colposcopists had scores below this standard. Comparisons were also made between presenting cytology, directed biopsy results, initial colposcopic impression, and final colposcopic evaluation (the clinical working diagnosis). The other major aspect of the quality-control program consists of an analysis of all cases of diagnosed invasive cervical cancer in the province in a given year to determine whether any colposcopically related errors occurred in the investigation and management of these cases. This system helps to identify individuals who may benefit from additional training.

Biopsy↗
PubMed1997

DXA longitudinal quality control: a comparison of inbuilt quality assurance, visual inspection, multi-rule Shewhart charts and Cusum analysis.

The performance of dual-energy X-ray absorptiometry (DXA) instruments can be monitored using various quality control (QC) procedures. It has not been established which of these is most appropriate. The aim of this study was to determine which of four QC procedures is the best to use for longitudinal monitoring. Eighteen centres with DXA instruments scanned an aluminium spine phantom weekly for up to 16 months, and the bone mineral density data were used for the QC procedures. The methods investigated were the instrument's inbuilt quality assurance (QA) procedure, visual inspection, multi-rule Shewhart control charts, and Cusum analysis using a truncated-V mask. True and false positive fractions (TPF and FPF) of each method were calculated, including those for a range of action levels for the Shewhart charts and dimensions of the Cusum mask. For Shewhart, the action levels giving the most desirable TPF and FPF were whole multiples of the standard deviation (SD). For Cusum, the most desirable mask dimensions were 3.6 SD for the total height of the vertical section and 0.9 SD per data point for the gradient of the wings. Predictive power of each method as a means of fault detection was decided by the number of faults detected out of a total of 8 non-mechanical faults subsequently diagnosed. The inbuilt QA detected 2, visual inspection 7, Shewhart chart 7 and Cusum analysis 7. The FPFs were: visual inspection 0.09, Shewhart 0.04, Cusum 0.08. At these levels of FPF, the average time in days (range) from onset of a fault to detection was 39 (6-82) for visual inspection, 39 (4-116) for Shewhart and 21 (1-49) for Cusum. All three "phantom" methods are excellent for DXA QC, with modified Cusum analysis being the most effective. The inbuilt QA appears of little use on its own for longitudinal QC.

Absorptiometry, Photon↗
PubMed1995

Radiation therapy quality control in a clinical trial of adjuvant postoperative treatment for rectal cancer.

PURPOSE: Deviations from protocol can detract from the reliability of results obtained in prospective clinical trials. In an effort to decrease the number of deviations in a prospective trial of adjuvant treatment for rectal cancer, we undertook pretreatment review of the irradiated fields. METHODS AND MATERIALS: Before initiation of radiation therapy, patients' radiation therapy fields were simulated by their radiation oncologists and films were submitted for review. The treating physicians were then informed whether their fields were in compliance with the protocol or whether any modifications were needed. RESULTS: Among the 625 patients participating in this study who received radiation therapy as a component of protocol treatment, 419 (67%) had no radiation therapy deviations, 127 (20%) had minor deviations, and 51 (8%) had major deviations; 28 (4%) could not be evaluated or did not receive protocol treatment because of circumstances beyond the treating radiation oncologist's control. The pretreatment quality control review identified major deviations in the radiation portals for 57 cases; these findings were communicated to the radiation oncologists prior to initiation of treatment, and, on final review, 40 had no deviation or only minor deviation. CONCLUSION: In the absence of pretreatment quality control review, 40 additional patients would have had major deviations from their radiation therapy protocol. On the basis of these findings, it is estimated that pretreatment quality control reduced the rate of major deviation from 15% to 8%. Pretreatment review of radiation therapy parameters is an effective method of reducing the frequency of major deviations in prospective clinical trials.

Clinical Protocols↗