Biomedical subjects

S S Ehrmeyer

Publications and source records attributed to S S Ehrmeyer.

28 records · Page 2Linked to original sources

PubMed1987

Interlaboratory proficiency-testing programs: a computer model to assess their capability to correctly characterize intralaboratory performance.

We developed a computer model of an interlaboratory survey program to study the ability of proficiency testing (PT) programs to detect intralaboratory errors (total, random, and systematic). It uses a base interlaboratory PT population of 400 laboratories and one test laboratory each with uniquely defined intralaboratory characteristics, i.e., mean, standard deviation (SD), and bias. A gaussian random-number generator uses these parameters to simulate 401 test results analogous to the analysis of one PT sample by each laboratory. The test laboratory's intralaboratory error is expressed as various combinations of bias and coefficient of variation (CV); its simulated survey result is evaluated by a performance criterion derived from the group statistics. To eliminate statistical artifacts, the computer model repeats the complete simulation process 400 times and determines the percentage of the test laboratory's results that fail to meet a specified performance criterion. The computer model can use assigned values or actual intralaboratory data.

Computer Simulation↗

PubMed1987

Ability of the 1(2)s rule to detect substandard performance in interlaboratory proficiency testing.

The most common evaluation criterion used by regulatory and voluntary interlaboratory proficiency testing (PT) programs to judge the quality of chemistry results is based on the group mean +/- 2.0 standard deviations (SD), the 1(2)s rule. The mean and SD are those of the selected PT population. Through computer simulations we have quantified, for the first time, the ability of the 1(2)s criterion to detect "acceptable" as well as substandard ("unacceptable") intralaboratory performance by PT. We found that the 1(2)s rule correctly identifies "acceptable" performance--i.e., low intralaboratory coefficient of variation (CV) values and small bias values--greater than 90% of the time. However, this criterion fails to detect laboratories with "unacceptable" bias and (or) CV at least 23% of the time. The high failure rate of the 1(2)s rule raises serious questions about its appropriateness for use by PT programs.

Computer Simulation↗

PubMed1987

An assessment of the use of fixed limits to characterize intralaboratory performance by proficiency testing.

Currently, proficiency-testing (PT) programs are expanding the use of fixed limits to evaluate interlaboratory performance. These limits are an attempt to relate total allowable intralaboratory analytical error and performance in a PT program. Fixed limits are a means of counteracting the effects of overly stringent performance requirements derived from the interlaboratory group mean and standard deviations (SD) achieved by today's very precise analytical systems. Our previously described computer model of a PT program is used to delineate the quantitative relationship between the magnitude of intralaboratory coefficient of variation (CV) and bias that is compatible with fixed interlaboratory limits of 5, 10, 15, and 20% relative error. However, fixed limits alone do not fully characterize intralaboratory performance. The efficiency, or the percentage of times a laboratory's PT results are required to fall within the fixed limit, also must be considered when criteria for PT performance are being set. For example, a 10% fixed limit and a 80% efficiency will allow laboratories having CV-bias combinations from 8%-0%, 7%-4%, etc., to pass PT. The use of a 95% efficiency will allow CV-bias combinations from 4.8%-0%, 3.5%-4%, etc., to pass PT. We give a figure that depicts all possible combinations for four fixed limits and six efficiencies.

Computer Simulation↗

PubMed1986

Quality control and quality assurance.

The office laboratory's need for quality is no different from that of any other clinical laboratory. If patients are to receive the benefit of physician's office testing, reliable, high-quality laboratory results are essential. To achieve this, the physician's office laboratory must have an adequate quality assurance program. Several fundamental components of such a program have been addressed in this article: procedure manuals, record-keeping, maintenance logs, quality control charts, participation in proficiency testing, and laboratory inspection. If your state's regulations do not yet require these activities in the physician's office laboratory, they soon will! A successful laboratory's quality assurance program will provide the following assurances. (1) Quality practices are established and followed by all personnel involved with the testing in the laboratory. (2) The technologist performing the test will know when systems and instruments are working properly and the patients' results are reliable. (3) High-quality information needed by the physician interpreting or evaluating patient laboratory results will be generated. (4) A set of written records is available demonstrating to the inspector that uniform and acceptable protocols have been established and are practiced in the laboratory. One short article cannot provide all the specifics for a laboratory's quality assurance program. The manufacturers and suppliers of instruments and reagents should be able to provide support in the following areas: calibration, type of controls to be used, development of a control chart, required maintenance procedures, establishment of accuracy and precision, and troubleshooting. If they cannot or will not, your laboratory should, perhaps, consider an alternative vendor to supply instrumentation and/or reagents. Additionally, resources such as the professional organizations, consultants, other clinical laboratories, and the inspectors or certifying agencies should also be considered in developing a comprehensive quality assurance program.

Ambulatory Care↗

PubMed1985

Adequacy of interlaboratory precision criteria in measuring intralaboratory performance.

We compared the predictive value of the various criteria used for grading pH and blood-gas measurements in interlaboratory proficiency testing programs with performance as determined from actual intralaboratory quality-assurance data. The evaluation criteria were the two-standard-deviation interval (2 SDI) proposed by the College of American Pathologists (CAP); CAP's proposed fixed criteria; and the fixed criteria of the American Thoracic Society (ATS). These were compared with 95% confidence limits derived from the individual laboratories' actual intralaboratory data. We found that the CAP's most-stringent criterion (2 SDI) overestimated the number of outliers (unacceptable results) for PCO2 and PO2, whereas the proposed fixed limits underestimated them. For pH and PCO2 the ATS's limits, which are more stringent, more closely match the individual laboratory's actual performance as measured by conventional (mean +/- 2 SD) intralaboratory quality-assurance practices.

Blood Gas Analysis↗

PubMed1985

Alternative statistical approach to evaluating interlaboratory performance.

We report a new technique for realistic assessment of laboratory performance as measured by proficiency testing. Interlaboratory results accumulated from 129 participants during 18 months provide the baseline data from which we established "state-of-the-art" performance criteria for three ranges of pH, pCO2, and pO2. By concurrent use of two statistical measurement techniques, the cumulative percentile rank and the algebraic and absolute mean error, laboratories can accurately evaluate their performance in terms of acceptable state-of-the-art criteria, total error, or medical usefulness. The approach facilitates assessment of the nature of the errors that have led to inferior performance and identification of probable areas where improvement is possible. If criteria based on regulatory standards or medical usefulness goals are included, the system can provide a basis for licensure or professional quality improvement.

Blood Gas Analysis↗

PubMed1984

Monthly interlaboratory pH and blood-gas survey. Establishing accuracy based on interlaboratory performance.

The authors describe an interlaboratory survey provided by their laboratory which enables participants to establish an accuracy base for pH and blood-gas determinations. Data collected from 131 laboratories provide insight into state-of-the-art performance capabilities. The percentile ranking system presented may be used by individual laboratories to determine their need for improvement or to set intralaboratory performance goals. Data accumulated from 18 months of interlaboratory surveys are used to establish performance levels at three concentration ranges each for pH, pCO2, and pO2. By characterizing average errors on a percentile ranking basis, the authors enable participants to assess their performance compared with peer laboratory results. For samples with normal pCO2 levels, 95% of reported laboratory results have an error of 4.5 mmHg or less. Similarly, 95% of reported results for normal pO2 samples have an error of 13 mmHg or less, and 95% of the pH results, independent of level, have an error of 0.05 pH units or less.

Blood Gas Analysis↗

PubMed1983

A comprehensive retraining program for inactive medical technologists.

Shortage of laboratory personnel appears to have created growing interest and activity in retraining inactive medical technologists. A recent three year program at the University of Wisconsin involving 63 individuals enrolled in one or more courses provides some results. Twenty-three are now employed, and nine are actively seeking employment. The development, presentation, evaluation and cost of the program are here reported.

Adolescent↗

PubMed1980

Continuing education: a practical programming model for new planners.

For allied health professionals to meet the proposed and required recertification/relicensure requirements, more continuing education programs will have to be made available. Consequently, more local and regional groups may have to become continuing education providers. Many of these providers, experts in their scientific fields, will be unfamiliar with adult education and the programming process. To assist them in planning and presenting sound continuing education, a basic model is proposed. The six steps in the programming model are detailed. It is hoped the model will serve as a useful guide for those responsible for program planning, presentation, and evaluation.

Allied Health Personnel↗

PubMed1979

Model course for retraining inactive medical technologists.

In the belief that there is an ongoing need for the retraining of inactive medical technologists, the University of Wisconsin-Madison initiated such a program in 1978. A model course in routine chemistry and instrumentation was developed, presented, and evaluated. This model is described in detail. Results indicate that most inactive medical technologists can regain competence. The program and individual courses are designed so they can be easily replicated or adapted for use by others interested in retraining inactive medical tehcnologists.

Clinical Competence↗