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PubMed2000

[Quality control during ultrasonographic evaluation of morbidity due to Schistosoma haematobium in Niger].

Within the framework of a campaign to control urinary schistosomiasis in Niger, a quality control audit was performed on ultrasonographic assessment of morbidity due to Schistosoma haematobium. The purpose of this audit was to determine variance and reproductibility of epidemiological data provided by two trained independent observers. Three parameters were studied, i.e.,: interobserver variability on matched data, interobserver variance at the community level on the same or different subjects, including some after treatment with praziquantel, and intra-observer variance. A total of 1750 ultrasound examinations were carried out on 1416 inhabitants from 10 hyperendemic villages (70 p. 100 schoolchildren) according to a slightly modified version of the WHO Cairo protocol. Inter-observer variance at the individual level was high for some elementary abnormalities of the bladder. Variance was around 20 p. 100 for the 2 main indicators, i.e. presence of at least one bladder lesion and dilatation of the upper urinary tract. At the community level, inter-observer variance was moderate and the two observers' global assessment of morbidity due to Schistosoma haematobium was the same. Variations of morbidity related to level of endemicity were given perceived in parallel. Similar findings were noted for the intra-observer variability at the individual or community level. Ultrasound examination is supposed to furnish reliable morbidity data for selecting communities at risk and scheduling treatments during schistosomiasis control programs. The results of this study show that the level of inter- and intra-observer variance in ultrasonographic assessment in Niger is compatible with this critical role.

Child↗

PubMedDate not supplied

Bovine blood quality control material for cadmium, mercury, and lead.

A protocol is elaborated for the preparation and characterization of a quality control material (QCM) containing intrinsic concentration of cadmium (Cd) (0.8 microgram/L) and lead (Pb) (13.4 micrograms/dL) from bovine blood and an elevated QCM containing Cd (5.0 micrograms/L), mercury (Hg) (11.2 micrograms/L), and Pb (34.5 micrograms/dL) from bovine blood spiked with aqueous spiking-solutions prepared with salts of Cd, Hg, and Pb. Borosilicate glass septum vials of 7-mL capacity were filled with 5 mL of blood, sealed with Teflon-silicone discs and plastic screw caps, and stored at -20 degrees C. Quality control, intervial and intravial, and storage stability values for Cd, Hg, and Pb were ascertained by analyzing the blood in randomly selected vials by an internal laboratory using modified published methods which were established for detection limit, accuracy, and precision. Validation of the protocol was demonstrated by intravial and intervial homogenity for Cd, Hg, and Pb and no change occurred in the concentrations of the elements in bovine blood containing EDTA at storage temperatures of 4 degrees C and -20 degrees C for 2 years.

Animals↗

PubMed2005

Inositol deacylation by Bst1p is required for the quality control of glycosylphosphatidylinositol-anchored proteins.

Misfolded proteins are recognized in the endoplasmic reticulum (ER), transported back to the cytosol, and degraded by the proteasome. A number of proteins are processed and modified by a glycosylphosphatidylinositol (GPI) anchor in the ER, but the quality control mechanisms of GPI-anchored proteins remain unclear. Here, we report on the quality control mechanism of misfolded GPI-anchored proteins. We have constructed a mutant form of the beta-1,3-glucanosyltransferase Gas1p (Gas1*p) as a model misfolded GPI-anchored protein. Gas1*p was modified with a GPI anchor but retained in the ER and was degraded rapidly via the proteasome. Disruption of BST1, which encodes GPI inositol deacylase, caused a delay in the degradation of Gas1*p. This delay was because of an effect on the deacylation activity of Bst1p. Disruption of genes involved in GPI-anchored protein concentration and N-glycan processing caused different effects on the degradation of Gas1*p and a soluble misfolded version of carboxypeptidase Y. Furthermore, Gas1*p associated with both Bst1p and BiP/Kar2p, a molecular chaperone, in vivo. Our data suggest that GPI inositol deacylation plays important roles in the quality control and ER-associated degradation of GPI-anchored proteins.

Acylation↗

PubMed2005

[Current situation of the external quality control survey provided by the Japan Medical Association and its problems].

The Japan Medical Association (JMA) has been providing the external quality survey program in clinical laboratory testing for the past 37 years, 2,812 labs participated in 2003, and it has improved overall interlaboratory variations, particularly in enzyme activity examinations. There are many other external quality survey programs provided independently by the other organizations, and the JMA Committee on Quality Control Survey in Clinical Laboratory Testing, in association with JCCLS and the other expert panels, had discussed on the possibility of implementing a new external quality assessment scheme, named NEQAS (National External Quality Assessment Scheme). The current problems on the external quality control survey are discussed.

Clinical Laboratory Techniques↗

PubMed1990

[Quality control of laboratory services in primary health care in Finland].

Finland is the only Nordic country with a nationwide system of quality control of the activities of the clinical laboratories, which covers both specialized and primary medical care. Practical experience of this quality control is reported. In empirical terms the organization functions well and the level attained by the health centre laboratories matches that of those at the central hospitals. Thus tests performed on patients at the health centres need not be repeated in hospital by reason of inferior quality.

Finland↗

PubMed2003

A novel approach for quality control of total lung capacity in the clinical pulmonary function laboratory: a study in a veteran population.

OBJECTIVE: Quality control in the clinical pulmonary function laboratory has been well developed for spirometry and diffusing capacity but not for the measurement of TLC. The purpose of the present study was to test two approaches to this problem. First, we compared TLC by body plethysmography (TLCb) with a value predicted from TLC measured by multibreath helium dilution (TLCm). Concordance between the measured and predicted values would imply the validity of the measurements. Second, we measured the test-retest variability of TLCb, TLCm and TLC measured by single breath helium dilution (TLCs) to assess the consistency of the measurements. METHODOLOGY: We performed a prospective study of 815 veterans. RESULTS: The prediction of TLCb from TLCm improved (r2 increased from 0.44 to 0.64) when FEV1/FVC and the difference between TLCm and TLCs were added to the model. The coefficient of variation for test-retest of TLCs, TLCm and TLCb were 8.9, 7.1 and 5.4%, respectively. Of all tests, 5.9% were inconsistent based on pathophysiology or measurement error and attributed mostly to TLCm. CONCLUSIONS: Prediction of TLCb from TLCm was not sufficiently accurate as to be useful for quality control. Comparison of TLCs, TLCm and TLCb may be useful for determining the internal data validity.

Airway Obstruction↗

PubMed1992

[Aspects of meat inspection in the framework of a system of Integrated Quality Control for slaughtering pigs].

This article evaluates different aspects of meat inspection that are important in an integrated quality control system for slaughter pigs. The meat inspection service registers post-mortem abnormalities. However, to achieve a reliable registration, it is necessary to be able to identify individual animals on the slaughter-line. The information about post-mortem abnormalities can be used by the meat inspection service. Percentages of abnormalities in a shipment of pigs were included in meat inspection indices. It was not possible to predict the percentages of abnormalities in shipment of pigs from individual pig suppliers, but it was possible to classify fattening herds according to the meat inspection index. Information about the pigs delivered from a fattening herd was provided in two ways: by delivering relevant information on a quality control card, and by preselecting (done by the pig supplier) pigs according to the presence or absence of abnormalities. With both methods it was possible to divide pigs into a group with and a group without post-mortem abnormalities. It is necessary that the information supplied is accurate. Information can be checked by screening a number of animals for drug residues (and zoonoses) at the slaughterhouse, and by checking the information registered by the pig supplier in logbooks kept on the farm. From a comparison of results obtained with a meat inspection method based on visual inspection (no incisions, no palpitation) of the carcass with those obtained with the regular meat inspection method, it can be concluded that many abnormalities are detected equally well with both methods. Some recommendations for further research are given.

Animals↗

PubMed1975

[Quality control of analyses and automation].

Multichannel analysers are becoming more and more usual in biochemistry laboratories. Then, a very severe quality control program is requisite. In Toulouse a three years experiment was carried out on a computer connected twenty four channels Autochemist and an unconnected Technicon SMA 12/60. The traditional quality control from control lyophilized serums is still necessary and useful, mainly at the level of a region. The remaining valuable methods are automatic calibration and statistical controls on frequently tested samples from human polled serum and on results from patients, these being provided through various procedures.

Autoanalysis↗

PubMed2004

Immediate postoperative angiography after aneurysm clipping--implications for quality control and guidance of further management.

BACKGROUND: To determine the impact of postoperative angiography after aneurysm clipping on quality control and further management. METHODS: A recent consecutive series of n = 296 patients (186 females, 110 males, mean age 51 yrs) who underwent 324 craniotomies to clip 384 aneurysms was reviewed. New irregularities on postoperative angiographies were categorized as unrelated (e. g. vasospasm) or related (= vessel occlusion/residuum) to clipping and expected or unexpected by the surgeon. Therapies prompted by these findings as well as subsequent negative sequelae were analyzed. Factors related to negative events were identified by logistic regression (p < 0.05). RESULTS: Twenty-six (8%) unrelated findings prompted medical or intravascular therapy. Of 36 (9.4%) clip-related findings (n = 17 occlusions, n = 19 residua), 14 (3.6%) were unexpected (n = 9 occlusions, n = 5 residua). This was followed by 9 (2.3%, n = 4 occlusions, n = 5 residua) clip readjustments and 6 aggressive medical therapies. Nine patients were scheduled for angiographic follow-up, of which in five performed so far no change of aneurysm remnants was noted. Permanent sequelae from vessel occlusion occurred in 9 cases. Major premature rupture (p < 0.005), giant size/fusiform configuration (p < 0.001), posterior circulation aneurysms (p < 0.05) and ophthalmic segment location (p < 0.008) were significantly related to adverse postoperative findings. The use of microvascular Doppler significantly reduced the rate of unexpected vessel occlusion (3.3 vs. 0.9%). CONCLUSIONS: Apart from the need for quality control in aneurysm clipping--especially with respect to coiling--our results stress the importance of postoperative angiography, because a small, but significant subset of patients will benefit from immediate intervention and/or deserves long-term follow-up.

Angiography↗

PubMed1996

The HERITAGE Family Study: quality assurance and quality control.

The HERITAGE (HEalth, RIsk factors, exercise Training And GEnetics) Family Study is the first multicenter family clinical trial of its kind. Conducted by a consortium of five universities in the United States and Canada, the study has as its primary goal to document the role of the genotype in the cardiovascular, metabolic, and hormonal responses to aerobic exercise training. A comprehensive protocol was implemented at four Clinical Centers (CC) for the generation of data on sedentary subjects. This group included 450 caucasians from 90 nuclear families (father, mother, three children) and 200 black subjects from 40 to 100 family units over a 5-year period. The entire family was tested before and after a 20-week exercise training program. The fifth participating center, the Data Coordinating Center (DCC), is responsible for data management and data analysis. A Consortium Coordinating Center (CCC) responsible for the overall coordination and direction of the study was established at the Quebec CC. Quality assurance and quality control are jointly coordinated by the CCC and the DCC. A multicenter study of this magnitude requires careful standardization of all procedures and constant monitoring of quality control at all levels of operation. This report describes the quality assurance and quality control measures implemented in the HERITAGE Family Study, including some examples with real data.

Adolescent↗

PubMed1993

Quality control functions of the Visual Field Reading Center (VFRC) for the Optic Neuritis Treatment Trial (ONTT).

The Visual Field Reading Center (VFRC) was established to assess visual field testing in the Optic Neuritis Treatment Trial (ONTT), to train and certify ONTT technicians, and to monitor the quality of the visual fields through evaluation of the technical aspects of the visual field testing. We describe the functions of the VFRC personnel and the standardized test protocols developed by the VFRC for Humphrey and Goldmann perimetry. We also describe the VFRC procedures for training and certifying visual field technicians, double-checking the eligibility of ONTT patients, assessing the quality of the visual field data, and processing visual field data. In addition, we describe the principles applied by the director and associate director of the VFRC in their clinical classification of the various localized and diffuse visual field defects observed in the Humphrey and Goldmann visual fields. The VFRC has processed more than 14,000 Humphrey and Goldmann visual field tests. The visual field quality control procedures and visual field defect classification process have been shown to be quite reproducible. Through quality control assessment procedures, we have been able to pinpoint a variety of problems at an early stage and promptly implement corrective measures. The standardized test protocols, technician training and certification procedures, and quality control assessment techniques used by the VFRC for the ONTT may serve as a model for future clinical trials employing visual field data as an outcome measure. These procedures can also be used to enhance visual field reliability in ophthalmological practices.

Education↗

PubMed1978

A stable blood product for pH-blood-gas quality control.

We describe how to prepare, store, and use a hemolyzed blood product for simultaneous pH, pCO2, and pO2 quality control. Tonometry of the blood product with two oxygen and two carbon dioxide concentrations resulted in consistent and reproducible values during 38 weeks. The resulting pH values were consistent and reproducible, demonstrating the metabolic acid-base stability of the blood product. We conclude that the proper preparation, storage, and use of the product results in consistent, reproducible, and economical quality control for pH, pCO2 and pO2 blood measurements.

Blood Chemical Analysis↗

PubMed2000

Quality control of oncology clinical trials.

This article discusses issues that are essential to ensuring the reliability of the conclusions of oncology clinical trials. Though quality control is important at every stage of a well-run clinical trial, the authors focus on the quality of the data as evidenced by the results and conclusions of the study. Good quality control principles and practices are discussed for study planning, design, conduct, analysis, and interpretation.

Clinical Trials as Topic↗

PubMed1982

Quality control of amitriptyline and nortriptyline plasma level assessments: a multicenter study.

Numerous studies report about the relationship between the clinical effectiveness of amitriptyline (At) and the plasma level of this drug and of its most important metabolite, nortriptyline (Nt). These agents are therefore very frequently examined for clinical applications and for research programmes in specialized laboratories. The experience with antiepileptic drugs suggests the necessity of quality controls for antidepressants also. Therefore, five institutions in Western Europe performed two such experiments within a year. Two kinds of blood samples were sent for analysis: 1. plasma samples spiked with different quantities of At and Nt from an untreated subject; 2. plasma samples from patients treated with clinical doses of At. Each laboratory happened to use a different analytical method: TLC, HPLC, GC-NPD, GC-FID and GC-MS. The results clearly show the usefulness and the necessity of quality controls for this category of drugs as well. They form the basis for the improvement of the methods of each laboratory in particular. In this context, intralaboratory quality controls are also possible, if one disposes of two different methods. The findings of this study suggest that published reports on relationships between clinical and pharmacological parameters should be considered critically as to possible methodological bias.

Amitriptyline↗

PubMed2004

Comparison of three commercial assays for the measurement of 17alpha-hydroxyprogesterone (17alpha-OHPR): limitations of the quality control system.

The measurement of 17alpha-hydroxyprogesterone (17alpha-OHPR) is of value for the diagnosis and management of congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency. In the central laboratory from 2000 to 2002, we observed, using the assay from the manufacturer DSL, an elevation of the moving average of 17alpha-OHPR concentrations and a number of adrenocorticotropic hormone (ACTH) stimulation tests despite the lack of any changes to the internal and external quality control, of which the criteria were continuously fulfilled. We studied a population of n=49 patients for the measurement of 17alpha-OHPR, with and without extraction, to evaluate the quality of different commercially available radioimmunoassays. The internal and external quality controls were successful in determining 17alpha-OHPR. An excellent measurement and correlation of 17alpha-OHPR was expressed with the assay from the manufacturer IBL without extraction and from the manufacturer DSL with extraction. The quantitative determination of 17alpha-OHPR requires adequate specificity and accuracy of the 17alpha-OHPR radioimmunoassays. The results show that internal and external quality control systems are not sufficient to resolve analytical problems described in this study.

17-alpha-Hydroxyprogesterone↗

PubMed2001

Quality-control issues on high-resolution diagnostic monitors.

Previous literature indicates a need for more data collection in the area of quality control of high-resolution diagnostic monitors. Throughout acceptance testing, which began in June 2000, stability of monitor calibration was analyzed. Although image quality on all monitors was found to be acceptable upon initial acceptance testing using VeriLUM software by Image Smiths, Inc (Germantown, MD), it was determined to be unacceptable during the clinical phase of acceptance testing. High-resolution monitors were evaluated for quality assurance on a weekly basis from installation through acceptance testing and beyond. During clinical utilization determination (CUD), monitor calibration was identified as a problem and the manufacturer returned and recalibrated all workstations. From that time through final acceptance testing, high-resolution monitor calibration and monitor failure rate remained a problem. The monitor vendor then returned to the site to address these areas. Monitor defocus was still noticeable and calibration checks were increased to three times per week. White and black level drift on medium-resolution monitors had been attributed to raster size settings. Measurements of white and black level at several different size settings were taken to determine the effect of size on white and black level settings. Black level remained steady with size change. White level appeared to increase by 2.0 cd/m2 for every 0.1 inches decrease in horizontal raster size. This was determined not to be the cause of the observed brightness drift. Frequency of calibration/testing is an issue in a clinical environment. The increased frequency required at our site cannot be sustained. The medical physics division cannot provide dedicated personnel to conduct the quality-assurance testing on all monitors at this interval due to other physics commitments throughout the hospital. Monitor access is also an issue due to radiologists' need to read images. Some workstations are in use 7 AM to 11 PM daily. An appropriate monitor calibration frequency must be established during acceptance testing to ensure unacceptable drift is not masked by excessive calibration frequency. Standards for acceptable black level and white level drift also need to be determined. The monitor vendor and hospital staff agree that currently, very small printed text is an acceptable method of determining monitor blur, however, a better method of determining monitor blur is being pursued. Although monitors may show acceptable quality during initial acceptance testing, they need to show sustained quality during the clinical acceptance-testing phase. Defocus, black level, and white level are image quality concerns, which need to be evaluated during the clinical phase of acceptance testing. Image quality deficiencies can have a negative impact on patient care and raise serious medical-legal concerns. The attention to quality control required of the hospital staff needs to be realistic and not have a significant impact on radiology workflow.

Calibration↗

PubMed2002

The role of intraoperative digital subtraction angiography for quality control of standard carotid endarterectomy using patch angioplasty.

The absence of technical defects is considered to be of great importance during carotid endarterectomy (CEA). In this context, both safe surgical technique and intraoperative quality control may be a fundamental part of the operative procedure. We have therefore undertaken a prospective study to evaluate the possible benefits of completion angiography in standard CEA using patch angioplasty. The objectives were three-fold: (1) to identify the incidence of defects requiring prompt revision; (2) to assess the perioperative stroke rate as well as the number of residual stenosis after 6 weeks in angiographically controlled patients and (3) to compare these results with a control group. From 1 January to 30 September 1999 111 patients with 115 consecutive CEAs which had completion angiography (Group A) were prospectively entered into this study. The results in group A were compared with a series of again 111 patients (Group B) which had 116 CEAs without intraoperative quality control between January and September in the year before. Surgical technique was identical in both groups. In general, risk factors were distributed evenly among both group with the exception that in group A were significantly more high-grade ipsilateral ICA stenoses while group B had more patients with diabetes and ipsilateral CT-defects. In group A, angiographic irregularities prompted us to immediate re-exploration in five patients (dilatation of severe ICA spasm 1; re-exploration of distal ICA occlusion 1; reopening of occluded ECA 3). With a 30 day mortality of 0% each perioperative stroke rate was comparable with 3/115 in group A and 3/116 in group B (P=1.0). 2/3 patients with neurological deficits in group A had early postoperative carotid thrombosis--in spite of a normal completion study. Duplex examination after 6 weeks revealed one asymptomatic ICA occlusion in each group. The incidence of residual stenosis (> or =50%) was not significantly different being 3.7% in group A and 3.2% in group B (P=0.85). When applying a safe and simple operative technique for CEA, the incidence of abnormalities warranting immediate correction appears to be a rare event and, therefore, the necessity for obligatory quality control may be questionable. On the other hand, completion DSA allows a simple documentation of the adequacy of the surgical procedure.

Aged↗

PubMedDate not supplied

X-ray waveform monitoring for radiographic quality control.

Noninvasive monitoring of x-ray output waveforms during acceptance testing, quality of control, and troubleshooting is beneficial in an ongoing radiographic quality assurance program. The intent of waveform monitoring is to watch for abnormalities that provide additional information about the condition of the x-ray system. Because waveform monitoring is performed generally in conjunction with other quality control procedures, few, if any, additional exposures are needed and length of the testing time is affected minimally. In six years of experience with acceptance testing, quality control, and troubleshooting on more than 160 radiographic and fluoroscopic units, noninvasive waveform monitoring has detected numerous abnormalities that would have affected image quality, generator calibration, and equipment life.

Quality Control↗