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Internal quality control: planning and implementation strategies.

The first essential in setting up internal quality control (IQC) of a test procedure in the clinical laboratory is to select the proper IQC procedure to implement, i.e. choosing the statistical criteria or control rules, and the number of control measurements, according to the quality required for the test and the observed performance of the method. Then the right IQC procedure must be properly implemented. This review focuses on strategies for planning and implementing IQC procedures in order to improve the quality of the IQC. A quantitative planning process is described that can be implemented with graphical tools such as power function or critical-error graphs and charts of operating specifications. Finally, a total QC strategy is formulated to minimize cost and maximize quality. A general strategy for IQC implementation is recommended that employs a three-stage design in which the first stage provides high error detection, the second stage low false rejection and the third stage prescribes the length of the analytical run, making use of an algorithm involving the average of normal patients' data.

Bias↗

Interinstitutional comparison of bedside blood glucose monitoring program characteristics, accuracy performance, and quality control documentation: a College of American Pathologists Q-Probes study of bedside blood glucose monitoring performed in 226 small hospitals.

OBJECTIVES: To assess the accuracy of bedside blood glucose monitoring (BGM) in small hospitals, to assess the compliance with which hospital workers performing bedside BGM adhere to quality control (QC) procedures, and to identify those practice characteristics in small hospitals that are associated with better BGM accuracy and with better performance of BGM QC. DESIGN: Over a 1-month period in 1996, voluntary participants in the College of American Pathologists Q-Probes laboratory quality improvement program prospectively compared glucose results of 30 split samples run on BGM instruments with those performed on laboratory glucose analyzers, collected quality control data on up to five inpatient BGM instruments, and completed questionnaires profiling BGM practice characteristics in their institutions. SETTING AND PARTICIPANTS: Two hundred twenty-six hospitals with 200 or fewer occupied beds. MAIN OUTCOME MEASURES: The percentages of glucose determinations performed on BGM instruments differing by more than 10%, 15%, and 20% from those split-sample results performed on laboratory glucose analyzers; the percent of BGM QC determinations required by institutions' BGM QC programs that BGM operators actually performed; and the percent of patient values reported when BGM QC was documented to be out of range and uncorrected, or reported when BGM QC was not performed at all. RESULTS: Of 6095 split-specimen glucose results that participants simultaneously performed on BGM instruments and on laboratory glucose analyzers, 45.6% differed from each other by more than 10%, approximately 25% differed from each other by more than 15%, and almost 14% differed from each other by more than 20%. Of 216 laboratories that performed at least 30 QC events during the study period, slightly over a third completed 100% of their required QC determinations, and 10% completed, at most, 77% of their required BGM QC determinations. Of 115,973 BGM determinations that participants reported on hospitalized patients, 3.3% were reported when QC was either out of range or when there was no documentation that QC had been performed at all. Better accuracy and/or better QC performance was associated with laboratory personnel rather than nursing personnel both supervising institutions' BGM QC programs and running institutions' daily routine BGM QC; with BGM operators both routinely running three, rather than two, levels of QC analytes; with BGM operators regularly comparing BGM results with laboratory analyzer glucose results; and with institutions participating in external proficiency programs. Institutions that completed all required BGM QC tasks tended to perform better on the BGM accuracy study than did those institutions that completed, at most, 77% of their required QC. CONCLUSIONS: We found the rates of BGM accuracy and of QC performance adequacy achieved in small hospitals to be similar to those determined in previous Q-Probes studies conducted in large institutions. A significant amount of institutional bedside testing does not meet current standards for accuracy or for quality control. Some institutions may improve their accuracy and/or QC performances by having laboratory personnel intimately involved in their institution's BGM QC program, by routinely comparing BGM results with those performed using glucose analyzers in the clinical laboratory, by routinely running three rather than two glucose QC control levels, by participating in external proficiency programs, and by strictly adhering to institutional QC protocols.

Australia↗

The use of embolic signal detection in multicenter trials to evaluate antiplatelet efficacy: signal analysis and quality control mechanisms in the CARESS (Clopidogrel and Aspirin for Reduction of Emboli in Symptomatic carotid Stenosis) trial.

BACKGROUND AND PURPOSE: The CARESS (Clopidogrel and Aspirin for Reduction of Emboli in Symptomatic carotid Stenosis) trial proved the effectiveness of the combination of clopidogrel and aspirin compared with aspirin alone in reducing presence and number of microembolic signals (MES) in patients with recently symptomatic carotid stenosis. The present study aimed at installing primary and secondary quality control measures in CARESS because MES evaluation relies on subjective judgment by human experts. METHODS: As primary quality control, centers participating in CARESS evaluated a reference digital audio tape (DAT) before the study containing both MES and artifacts. Interobserver agreement of classifying signals as MES was expressed as proportions of specific agreement of positive ratings (ps+/-values). For all DATs included in CARESS (n=300), online number of MES and off-line number of MES read by the central reader were compared using correlation coefficients. As secondary control, a sample of 16 of 300 DATs was cross-validated by another independent reader (post-trial validator). RESULTS: For the reference tape, the cumulative ps+/-value was 0.894 based on 12 of 14 observers. Two observers with very different results improved after a training procedure. Agreement between post-trial validator and central reader was ps+=0.805, indicating very good agreement. Correlation between online evaluation and off-line evaluation of DATs was very good overall (cumulative rho=0.84; P<0.001). CONCLUSIONS: Multicenter studies using MES as outcome parameter are feasible. However, primary and secondary quality control procedures are important.

Aspirin↗

Importance of a arteriography for intraoperative quality control during carotid artery surgery.

The purpose of this study was to determine the impact of intraoperative quality control using arteriography on the conduct and immediate outcome of carotid artery surgery. This retrospective study included 623 carotid artery repair procedures performed between January 1993 and January 2000. There were 427 men and 159 women (37 bilateral procedures) with a mean age of 71.6 years. The repair technique consisted of conventional endarterectomy alone in 353 cases, conventional endarterectomy with patch closure in 95 cases, eversion in 44 cases, and vein (n = 105) or prosthetic (n = 26) grafting in 131 cases. Findings of intraoperative arteriography, which is used routinely in our department, were reviewed and analyzed in all cases. Our findings indicate that intraoperative quality control with arteriography is an important part of carotid artery surgery. In 11.7% of cases in this study, intraoperative arteriography revealed significant defects that are the main cause of postoperative neurological complications.

Adult↗

Quality control in immunocytochemistry: experiences with the oestrogen receptor assay.

AIMS: To evaluate the feasibility of an interlaboratory quality control programme in immunohistochemistry. METHODS: Several pathology laboratories were asked to carry out immunohistochemical oestrogen receptor staining on a set of freeze dried cryostat sections of breast cancer tissue. The sections and protocols for staining and semi-quantitative scoring were mailed to the participating laboratories in two trials. The oestrogen receptor content of the breast cancer samples was determined by radioligand binding assay on the tumour cytosol. RESULTS: In the first trial 11 laboratories (response rate 60%) participated. Eight (73%) of the participants scored within a 95% confidence interval and all but one correctly classified the tumour as receptor positive. In the second trial all 20 participating laboratories (response rate 55%) correctly scored one tumour sample as negative and 18 of them (90% of respondents) correctly classified the two other tumour samples as receptor positive. In a quantitative evaluation a histochemical score within 95% confidence interval limits was provided by eight (40%) and 12 (60%) of the participants. CONCLUSIONS: Semiquantitative scoring of immunocytochemical staining is valuable for performing correlative inter-laboratory studies, although this scoring protocol may not be required for diagnosis or prognosis. Significant inter-laboratory variability exists, leading to qualitatively correct receptor classification in 100% of receptor negative and 80% of receptor positive cases, and quantitative agreement in only about half of the cases. The perceived variability is not caused by systematic differences in the choice of the immunocytochemical technique, or the mailing of freeze dried sections. Quality control programmes should be included in the standard procedures of each diagnostic immunohistochemistry laboratory.

Breast Neoplasms↗

Automated quality control of emission-transmission misalignment for attenuation correction in myocardial perfusion imaging with SPECT-CT systems.

BACKGROUND: Emission-transmission misalignment with single-photon emission computed tomography (SPECT)-computed tomography (CT) systems can impair attenuation correction (AC) in myocardial perfusion imaging. This study was performed to develop automated quality control (Auto-QC) to detect critical misalignment that can significantly impact AC. METHODS AND RESULTS: Auto-QC was developed to segment myocardium and mediastinum from emission and transmission reconstructions, respectively. Myocardium-mediastinum mismatch was used as the quality-control index (QCI). The QCI threshold for acceptable AC was determined with NCAT (NURBS [nonuniform rational B-spline]-based cardiac torso phantom) simulation and verified with 2 patients with minimal misalignment. Compromised data sets, generated by shifting the attenuation maps by 0.5, 1.0, 1.5, and 2.0 pixels along left-right, up-down, and head-foot directions, respectively, were qualitatively and quantitatively compared with the unshifted data sets. Auto-QC was tested with the 2 verification patients and 41 additional patients. Shifts by more than 1 pixel along any direction compromised AC. Auto-QC with the QCI threshold (3%) had highly concordant results with manual quality control in the detection of critical misalignment (sensitivity of 88% and 90% and specificity of 93% and 95% for the tests by use of the 2 verification patients and 41 additional patients, respectively). CONCLUSION: QCI quantitatively represented the severity of misalignment. Auto-QC can help clinicians be aware of critical misalignment and can assist in realignment of SPECT and CT images.

Algorithms↗

Liquid chromatographic-tandem mass spectrometric urine assay for a highly metabolized cyclic ureidobenzenesulfonamide: issues concerning assay specificity and quality control preparation.

An LC-MS-MS method was validated for the quantitation of a beta(3) agonist (A) in human urine to support Phase I studies. A was designed to accelerate metabolism for weight reduction. During assay development a significant loss of A was apparent from frozen urine quality control samples. The addition of 0.75% bovine serum albumin (BSA) in urine (v/v) was required to maximize the recovery of A from urine. Urine samples were basified and extracted into methyl t-butyl ether-isopropyl alcohol (90:10, v/v). The organic layer was washed, evaporated, reconstituted, and injected onto a 5 cm, C8 HPLC column prior to MS-MS analysis. The standard curve was linear from 5 to 500 ng/ml. Intraday precision for peak area ratios from BSA urine samples at seven separate concentrations over a range of 5-500 ng/ml (n=5) was <4.0% and calculated concentrations were within 91-115% of nominal concentrations. Interday precision for BSA urine quality control (QC) samples at four separate concentrations (n=10 of each) was <5.0% and individual calculated concentrations were within 90-111% of nominal concentrations. This work emphasizes that potential metabolites and quality control standards should be prepared and assayed as early as possible in method development, especially before the sample collection section of the clinical protocol is prepared. The methods described here have wide utility to other compounds containing basic benzene sulfonamides and to beta3 agonist candidates.

Adrenergic beta-Agonists↗

A quality-control procedure on cervical lesions for the comparison of cytology and histology.

A new method for the quality control of cytologic and histologic diagnoses of cervical lesions is based on the automated high-resolution scanning, image processing and computer analysis of cytometric data by the TICAS system. It determines and then compares optical-density-based ploidy patterns of cells in cytologic smears and the corresponding histologic sections, with the results available both as computer-graphic displays and printouts. Examples of the former appear for an "agreement case," in which the cytologic and histologic patterns corresponded, and a noncorrespondence (nonrepresentative) case, in which the tissue sample had been nonrepresentative of the lesion sampled by cytology. Computergraphic examples concern one case of condyloma and one of tissue repair, in both of which both the cytologic and histologic diagnoses had been overcalled. A further example shows the method's use in monitoring response to therapy. The DNA ploidy patterns on which this method is based can give diagnostic and prognostic clues when morphology alone may be equivocal or insufficient. The utility of ploidy pattern determinations of material from other body sites is also well established. With the use of microprocessors, the system described could be made inexpensive and operationally simple for the routine quality control of many cytopathologic studies as well as for the clinical follow-up of patients.

Adult↗

[15O]H2O, [15O]O2 and [15O]CO gas production, monitoring and quality control system.

The 15O gas production system selects the gas production mode, monitors gas delivery conditions and performs quality control needed during the production and delivery of continuous flow radioactive gas for equilibrium and bolus PET studies. Target gas switches choose the appropriate valve positioning for [15O]H2O, [15O]O2 or [15O]CO production while flow rate, pressure and radioactivity are constantly monitored. The system also includes an IBM PC interfaced gas chromatograph which provides chemical and radiochemical quality control by on-line, real time, gas sampling of the delivery line.

Carbon Monoxide↗

Application of two-dimensional nuclear magnetic resonance spectroscopy to quality control of ginseng commercial products.

Ginseng has been used as a powder or a crude extract of the plant roots. The quality control of commercial ginseng preparations is difficult due to the diverse compounds present. Most previous quality control methods using TLC or HPLC-UV (or -MS) cannot be expected to cover a wide range of compounds in the commercial ginseng preparations. In this study, the metabolic fingerprinting of ginseng preparations was performed by (1)H-NMR spectroscopy. Although (1)H-NMR spectroscopy could provide information about the total profile of the compounds present, low resolution and overlapping signals make it difficult for further identification of each compound. For overcoming the problem two-dimensional J-resolved NMR spectra and multivariate data analysis techniques was applied for the analysis. Principal component analysis (PCA) of projected J-resolved NMR spectra shows a clear discrimination among those samples by principal component 1 and principal component 3. The loading plot of PC values obtained from all NMR signals indicates that alanine, arginine, choline, fumaric acid, inositol, sucrose as well as ginsenosides are important metabolites to differentiate the preparations from each other. This method allows an efficient discrimination of a ginseng preparation in less than 15 minutes without any pre-purification steps.

Humans↗

[Management of errors in hospital laboratories--Total Quality Control and lists].

Errors in the daily routine work of a hospital laboratory vary. Therefore, measures to prevent errors must be devised. It is important to perform Total Quality Control (TQC) and to provide reliable diagnostic information and this does not stop at quality control of mere assay value, but extends to consideration of the correspondence to a patient. It is absolutely necessary to reduce errors in a laboratory and to perform TQC steadily. Therefore, the concept of TQC is divided roughly as follows 1) Safe management, 2) Technical management, 3) Information management, 4) Materials management. These categories are then subdivided even further. These categories relate to error management because it is considered that the manuals for technical and information management are important. It is necessary to create an error processing ledger to collect information for error management for TQC and for prevention of errors in investigating causes and to record all processes according to the contents of the error. Such records can be used to prevent recurrences. Thereby, not only prevention of errors but also improvements in the accuracy and reliability of information offered are thought to become possible.

Clinical Laboratory Techniques↗

[The procedures and results of a quality control program in mammography carried out on a regional basis].

In 1990 the region of Tuscany instituted a quality control program for mammography, in order to check the working conditions of mammography centers in the region, to investigate the feasibility of applying some working standards in line with European recommendations, and to promote the training of personnel. The program involves the following: a test of newly acquired mammographic equipment to establish that it meets the required standards; an annual test of generators, X-ray beams, grid, AEC, screen-film system, film processing, dose and image quality; daily test (phantom radiography and film sensitometry) performed by the personnel of each mammographic Unit; and a sustained advisory service for the technical problems occurring between checks. Thirty-nine of 57 centers participated on a voluntary basis, and 135 checks were performed annually. The results of the program show a performance below the recommended standard in relation to AEC, film sensitometry and the adequacy of lights in dark rooms in 40%, 50% and 63%, respectively, of the centers. Entrance exposure was over 1500 mR, with a maximum value of 3450 mR, in 6 cases in the first round. 5 cases in second, and only 1 case in the third. In general, the results are slightly improving, but mammography optimization is still a long way off. It is necessary to carry out suitable programs for quality control in mammography on a regional basis and to establish precise guidelines for individual mammographic Units to follow in order to meet the European standards.

Breast↗

Quality assurance in medicine: research and evaluation activities towards quality control in Singapore.

Quality assurance and medical audit requires a good Health Management Information System (HMIS) to support it. In Singapore, there is a well developed HMIS built on the routine reporting of utilisation and activity statistics from public sector and private sector hospitals, government clinics and support services. In addition, there is a computerised national surveillance system for disease monitoring, which includes the disease condition, operations done and the physician and surgeon responsible for managing any inpatient or day case admitted into any hospital in Singapore. This forms the basis for the computerised national health system known as Medinet. Supplementing this are ad hoc surveys on quality of service, medical audit studies and supplementary information systems such as the Births and Deaths registration system and the Census of Population. Such a well developed HMIS greatly facilitates medical audit in Singapore. Indicators for audit can be generated from existing health databases, which point to areas requiring further inquiry and investigation. The use of a unique National Registration Identity Card (NRIC) for every Singaporean enables healthcare utilisation at all levels to be linked, further enhancing the capability for medical audit here.

Databases, Factual↗

Alkaline phosphatase activity in lyophilised quality control serum.

The rise in alkaline phosphatase activity has been studied after reconstitution of 16 commercial preparations of lyophilised quality control material. The effects of storage temperature and analytical method on the rise in activity have also been studied, with a view to producing a reconstitution protocol suitable for recommendation to participants in external quality control surveys. Great differences were found in the magnitude of this rise in activity; these differences can be reduced to negligible levels if the material is mixed for 30 minutes at ambient temperature after reconstitution and then stored for not more than 4 hours at 4 degrees C before assay.

Alkaline Phosphatase↗

An improved (99m)Tc-aprotinin kit formulation: quality control analysis of radiotracer stability and cold kit shelf life.

(99m)Tc-aprotinin scintigraphy has been demonstrated to be a useful noninvasive imaging technique for amyloid deposits located in extraabdominal regions of patients. The aim of this study was to develop an improved aprotinin cold kit formulation, to validate the kit for long-term stability, as well as to assess the radiotracer stability by novel quality control methods. The aprotinin cold kit formulation of Trasylol, pyrophosphate (PYP)-chelated stannous reductant and an alkaline buffer, was dispensed into nitrogen-filled vials and aliquots frozen at -20 degrees C. After 0, 1, 2, 3 and 6 months of storage, three samples were reconstituted with 750-850 MBq of (99m)Tc-pertechnetate, followed by quality control analyses by paper chromatography methods at 25, 85 and 265 min postreconstitution (pr). Cation-exchange cartridge quality control methods were also investigated. The cold kits proved to be stable to long-term storage for up to 6 months, and the radiotracer was stable for at least 4 h pr. (99m)Tc-aprotinin was formed at greater than 95% efficiency at all time points tested with (99m)TcO2 present as the major impurity (1-4%) and (99m)Tc-pertechnetate and (99m)Tc-PYP present in trace amounts. An alternative, rapid, safe and reliable method was found in Oasis MCX-BSA-treated cartridges using saline as the eluting solution to assay for (99m)Tc-aprotinin.

Aprotinin↗

Analyzing quality-control trends with moving slope charts.

We have developed and evaluated a new procedure for detecting trends in quality-control measurements and applied it to laboratory data. The method requires the use of sequential or "moving" slope estimates to identify trends. Formulae are derived to estimate the regression error for the moving slope directly from the standard deviation of the analytical measurements obtained during characterization runs. Control limits for the moving slope depend only on this regression error, the span of the slope, and the desired statistical level of control. The moving slope can be plotted with control limits to determine out-of-control points. The statistical power of the moving slope is found to be much greater than that of an often-used test for trends. An example of the use of the moving slope is shown for quality-control measurements for total cholesterol obtained over several years. We conclude that the moving slope procedure has considerably more statistical power than trend rules and that it yields more useful information to the analyst.

Biometry↗

Advantages of CUSUM techniques for quality control in clinical chemistry.

The performance of routine analytical laboratories is assessed, inter alia, by the use of appropriate internal quality control techniques. Despite evidence that the cumulative sum technique is generally superior to Shewhart-type control charts and many others, its use has been limited by the popular misconception that it is inferior to Shewhart's in detecting large variations and/or outliers in quality control data. The application of computer simulation methods has enabled us to answer this criticism and has provided the basis for further improvements in the design of the appropriate control scheme for general use in clinical chemistry.

Chemistry, Clinical↗

Assessment and quality control of incontinence care in long-term nursing facilities.

A statistical quality-control process was used to assess how well incontinence management procedures were being implemented by indigenous nursing staff in four nursing homes. Eighty-one incontinent patients were treated with the prompted-voiding toileting procedure. Thirty-six of these patients proved responsive to the toileting procedures, and nursing home staff was instructed to maintain the toileting program for these responsive patients. The first part of the quality-control model involved setting job standards specifying how dry the patients should be if toileted on a 2-hour schedule. Second, a job-monitoring control chart was used to continuously assess how well the job standards were being met. The remaining forty-five patients, who were unresponsive to the toileting protocol, were managed with a 2-hour changing schedule. Job standards specifying how wet (volume) the patient would be if changed on a two-hour basis were set. Control-chart monitoring of these patients urine output assessed how well the changing procedures were being implemented. Incontinence care in nursing homes is difficult to supervise because of problems in measuring how consistently nursing aides change or toilet patients. This paper describes a management system for effective incontinence care.

Aged↗