PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Quality Control”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed1977

Combined Shewhart-cusum control chart for improved quality control in clinical chemistry.

We describe the adaptation of the decision limit cumulative sum method (cusum) to internal quality control in clinical chemistry. With the decision limit method, the cusum is interpreted against a numerical limit, rather than by use of a V-mask. The method can be readily implemented in computerized quality-control systems or manually on controls charts. We emphasize the manual application here and demonstrate how the technique can be implemented on existing Shewhart or Levey-Jennings control charts. This permits both cusum and Shewhart control rules to be used simultaneously on a single control chart and also minimizes the data calculations necessary for the cusum method. Computer simulation studies are used to determine the performance characteristics of several different cusum rules, alone and in combination with a Shewhart rule. These studies indicate that improvements in existing quality-control systems should be possible by addition of this simple cusum method and by use of a combined Shewhart-cusum control chart. This should be particularly advantageous when introducing the cusum method in laboratories with manual quality-control systems.

Chemistry, Clinical↗
PubMed1979

An investigation into the distribution of radial immunodiffusion quality control data.

Quality control data from routine radial immunodiffusion assays for IgG, IgA, IgM, C3, C4 and alpha1-antitrypsin were tested by the Kolmogorov--Smirnov procedure for gaussian distribution. All but alpha1-antitrypsin were nongaussian in type. Further analysis of these date by plotting on log-normal probability paper showed them to have a log-normal distribution. Treatment of the date by either gaussian or nonparametric statistical methods produced little difference in confidence limits. It does not appear necessary to use nonparametric methods to calculate confidence limits from quality control data for the procedures studied.

Complement C3↗
PubMed1979

Suitability of commercial control sera for the quality control of activity determination of alkaline phosphatase.

The suitability of thirteen commercially available control sera for measuring alkaline phosphatase (EC 3.1.3.1; orthophosphoric acid monoester phosphohydrolase, ALP) activity in human serum was tested. Apart from differences in ALP activity observed in some reconstituted commercial sera, the behaviour of control materials towards experimental variables such as the nature and concentration of the substrate, pH and type of buffer (or PO4-acceptor) together with the composition of the isoenzymes present in human serum highlights the problems and difficulties if commercial materials are to be used as control sera. The half-saturation constants in control sera were in all cases smaller than those of ALP isoenzymes from bone and liver. The shape of substrate activity curves and the pH optimum in most of control sera differed from that of human serum. The discrepant kinetic data of control materials and human serum may mask or suggest changes relevant to commercial quality control serum but not to samples of human serum.

Alkaline Phosphatase↗
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↗
PubMed1979

Accuracy in interlaboratory quality control programs.

Interlaboratory quality control programs provide an important contribution to achieving and maintaining accuracy in clinical laboratories. The various strategies for providing accurate target values in the two principal types of interlaboratory programs are reviewed.

Laboratories↗
PubMed1978

Serum cholesterol analysis in the C.B. Heart Project. Intra-and inter-laboratory continuous quality control.

Standardization and quality control of measurements are of crucial importance in large medical surveys. In the C.B. Heart Project serum cholesterol analyses in the central laboratory were extensively controlled with regard to precision as well as accuracy. All measurements are carried out in side-by-side duplicate, the maximum difference allowed being 0.3 mmol/l. Bench control, aiming at maintaining linearity and precision with control limits, requires insertion of standard solutions and several serum controls into every run. Control values must fall within 2 S.D. limits from the established mean values, e.g. 4.1 +/1 0.25 mmol/l and 8.2 +/- 0.25 mmol/l. A very reliable check on the precision was obtained by blind introduction of duplicate patient specimens. Repeatability (within-run precision) as calculated each month has S.D. values of approx. 0.10--0.20 mmol/l, whereas reproducibility (long-term precision) S.D. values are 0.15--0.25 mmol/l. Accuracy is checked in the Cooperative Standardization Programme of the WHO Regional Lipid Reference Centre in Prague. This makes the C.B. Heart Progject results comparable with other standardized studies. Our bias approximates +3% and usually remains within WHO "narrow limits".

Cholesterol↗
PubMedDate not supplied

[Quality control in microbiology (author's transl)].

The microbiology quality control importance is emphasized and some particular problems that quality control presents in microbiology are also indicated. There are two types of microbiology quality control as well as for hematology and chemical chemistry: collective quality control, between more laboratories, and individual quality control, in the sphere of each laboratory. A.M.O.I. (Associazione Microbiologi Ospedalieri Italiani) and I.S.V.T. (Istituto Sieroterapico Vaccinogeno Toscano) Sclavo collaborating, have organized a collective quality control between laboratories of different hospitals during the year 1974 and 1975. The results of this control are reported. Although preliminary, they indicate practical importance of microbiology control. During 1975, in fact, the pathogens isolated have been in high percentage than 1976. At last, the future quality control's program aiming at methods's standardization and technical, methodical instructions is indicated.

Bacteriological Techniques↗
PubMed1978

Long-term stability of glucose in lyophilized quality control serum. A study utilizing data from the Quality Assurance Service (QAS) Program of the College of American Pathologists.

The long-term stability of glucose in 45 commercial pools of lyophilized quality control serum is evaluated. The pools have been used in conjunction with the Quality Assurance Service (QAS) of the College of American Pathologists by laboratories participating in Regional Quality Control Programs. Directional instability of glucose was detected by at least one analytic method in 69% of the pools studied. Two distinct and opposite directional trends in glucose concentration were found. Increasing concentration of analyte, averaging 4.7 mg/dl per year, were observed with manual and automated glucose oxidase methods and the automated neocuproine procedure in approximately one fourth of pool--method combinations. Decreasing concentrations of glucose, averaging 3.0 mg/dl per year, were found with automated ferricyanide and hexokinase methods and the manual orthotoluidine procedure in approximately one third of pool--method combinations. The results are best explained by postulating that in affected pools there is a gradual diminution of free and bound glucose and/or a shift of glucose from the protein-bound to the free state.

Autoanalysis↗
PubMed1977

Suitability of commercial enzyme control sera for the quality control of activity determinations of L-aspartate aminotransferase and L-alanine aminotransferase in human serum.

Details of a systematic approach to suitability testing of commercial control sera are given for substrate optimized L-aspartate aminotransferase and L-alanine aminotransferase methods at 37 degrees C. Their acceptability for control purposes of standardized methods depends on: (1) the range of control values in relation to borderline values, (2) stability, (3) aspect, clarity, (4) NADH consumption in preincubation time, (5) blank activities, (6) kinetic data as half saturation constants and saturation curves, (7) influence of effectors, (8) isoenzyme pattern. These evaluation criteria are proposed for suitability testing. The term "representativeness" should be introduced as a special criterion for main characteristics of control materials. The authors want to point out the close connection with standardization of methods.

Absorption↗
PubMed1979

Stability of mean values of organic analytes in lyophilized quality control serum. A study utilizing data from the Quality Assurance Service (QAS) Program of the College of American Pathologists.

The long-term stability of mean values of six organic analytes in 48 commercial pools of lyophilized chemistry quality control serum is evaluated. These pools, provided by five manufacturers, have been used by nine Regional Quality Control Programs participating in the College of American Pathologists Quality Assurance Service. Creatinine yielded stable mean values in 88% of the pools studied. Both albumin and urea nitrogen demonstrated manufacturer and method-related changes in mean values. Bilirubin, cholesterol, and uric acid changes in mean values were independent of control serum manufacturer, predominant in calibrator-standardized automated procedures, and were clustered by years.

Bilirubin↗
PubMed1977

Mycological culture media and its quality control.

The need for control of the quality of media used in the isolation and identification of fungi is an important aspect of the overall quality control of laboratory culture media; however, guidelines for such controls have not been available. In this paper, primary isolation media with and without appropriate drugs are suggested for use on a variety of specimens. Positive and negative quality control organisms that indicate clear-cut postiive and negative results on the fungal media to be tested are listed. Several alternative procedures for maintenance of fungi are discussed.

Culture Media↗
PubMed1978

HACCP models for quality control of entrée production in hospital foodservice systems. II. Quality assessment of beef loaves utilizing HACCP models.

HACCP models were developed for quality control of entrée production in three hospital foodservice systems: Conventional, cook/chill, and cook/freeze (1). The three systems were stimulated in a laboratory to evaluate the effectiveness of the HACCP models for quality control and to generate quantitative data for evaluating and comparing the quality of beef loaves produced under controlled conditions. Attributes measured were weight (yield) and microbiologic, nutritional, and sensory qualities. The only significant difference in the beef loaves among systems was sensory quality. Scores for overall acceptability of beef loaves in the conventional system were significantly greater (P less than 0.05) than for those of the cook/chill and cook/freeze systems. The HACCP models were effective quality control tools for entrée production; implementation of the HACCP system is recommended for hospital foodservices. The importance of the time-temperature critical point for monitoring control points in hospital foodservice systems is emphasized.

Animals↗
PubMed1979

Quality control by blind sample analysis.

Quality control efforts may be biased consciously or unconsciously. External programs are handicapped by the time lapse before poor performance is disclosed. Bias induced into internal and external quality control efforts by special handling may be eliminated through submission of blind samples originating from wards, clinics, or phlebotomy areas. Evaluation of laboratory performance is obtained under conditions similar to those experienced by the patients' specimens. Calibration performance by operators, which varies considerably, can be monitored. Laboratory clerical activity can be scrutinized and errors quantitated and corrected. Perhaps most important, the sum of the effects of specimen handling and analytic variability can be determined.

Alkaline Phosphatase↗
PubMed1978

Use of a programmable desk-top calculator for the statistical quality control of radioimmunoassays.

We have developed an interactive statistical quality-control system for the small- to medium-sized radioimmunoassay laboratory, which can be used in a programmable desk-top calculator instead of the medium- or large-scale computer systems usually required. The design of this quality-control system is modeled after the suggestions of Rodbard and has three components. The first component evaluates the relationship between the measured response variable of the radioimmunoassay and the precision (or variance) of these measurements. This derived relationship is then used in the second component of the system as the basis for the weighting function used to calculate an interative, weighted, least squares regression of the logit-log transformation of the dose-response curve. The third component uses the quality-control parameters statistically calculated from the linearized dose-response curve to monitor whether the assay is "in-control". The calculator tabulates the means and confidence limits for the various parameters and can plot the statistical quality-control charts. The major benefit of this statistical quality-control system is that it allows the real-time computation and plotting of quality-control data with a programmable desk-top calculator.

Computers↗
PubMedDate not supplied

[Quality control in parasitology].

A quality control in parasitology has been organized since 1977, under the direction of the Exotic Pathology Society. In 1978, more than 1 200 voluntary laboratories were participating. In 1979, according to the law of the eleventh of July 1975, this control is going to be obligatory for the 3 750 public or private laboratories effecting parasitologic tests. That should improve the quality of these tests, outside any repressive aspect.

France↗