Comparison Of Laboratories Research Articles

Static Evaluation of Pedicle Screw Spinal Constructs to the ASTM Standard: A Comparison of Multiple Test Laboratories

Abstract Newly acquired mechanical test data along with predicate device data—sometimes from the designer’s historical records—are a requisite part of the regulatory submission process for new pedicle screw spinal constructs. Several studies have compared the mechanical properties of various designs of these medical devices, which are commonly inserted during spinal fusion operations. However, a rigorous comparison of the results coming from different laboratories testing the same devices under controlled conditions has not been performed. Six different test labs performed a series of static bending compression and static torsion tests on identically prepared pedicle screw and rod test constructs (n = 5 for both tests). Sufficient data were acquired to uncover and understand differential interpretations of the methodology described in the standard test method ASTM F1717. For ultimate displacement in compressive bending, the mean values ranged between 47.64 mm and 71.64 mm, and every single laboratory’s data were statistically significantly different from those of every other laboratory. Significant differences in the mean values carried through to the ultimate load data, but this trend did not continue for stiffness, yield displacement, yield load, and elastic displacement. For stiffness in static torsion, the mean values ranged between 0.38 Nm/° and 1.07 Nm/°. There were statistically significant differences among some of the labs for some of the parameters, but no strict patterns emerged. This is likely due to methodological and interpretive differences among the labs, such as the depth of the clevis fixtures and the direction of rotation during torsion testing. These differences in the test labs’ methodology have caused the ASTM subcommittees to clarify the standard so that fewer aspects are open for interpretation, but more work is needed. With appropriate refining of F1717 (and adherence to the new methodology by the test laboratories), test results from different laboratories would likely be more directly comparable than in the current situation.

Retrospective analysis of 88,429 serum and urine glucose EQA results obtained from professional laboratories and medical offices participating in surveys organized by three European EQA centers between 1996 and 2007

The aim of this study was to provide inter-laboratory imprecision comparisons of different groups of diagnostic systems as well as a comparison of professional laboratories with medical offices performance on the basis of 88,429 glucose results obtained in external quality assessment (EQA) schemes organized by three European EQA centers between 1996 and 2007. A simple, non-parametrical statistical model suited to all EQA results, including outliers, was used to calculate yearly and global performance. The best performance was obtained from professional laboratories with a group of three diagnostic systems--Hitachi, Integra, and Vitros, followed by Cobas Mira, and finally by Reflotron. For medical offices, the best performance was achieved with the Cobas Mira diagnostic systems, followed by the Reflotron, SpotChem, and Vitros DT60 diagnostic systems. A slight but overall improvement in performance over time was observed for most diagnostic devices. The analysis of glucose EQA results collected over a 12-year period showed that professional laboratories obtained better performances than medical offices, and that a general improvement in yearly performance was observed for both types of laboratories.

Organisation of proficiency testing for plant health diagnostic tests: the experience of FAPAS®

Proficiency testing (PT) is an established quality assurance measure and is based on the comparison of laboratories’ results in an inter‐laboratory trial. It highlights problems in laboratory analysis and is an educational tool to help improve data quality. This article describes how PT is organised by FAPAS®. FAPAS® is an international PT provider (external quality assessments) for food chemistry, food microbiology, genetically modified material and water/environmental samples. Since 2007, FAPAS® have organized plant health proficiency tests in conjunction with the Plant Pest and Disease Identification Programme at the Food and Environment Research Agency (Fera). Up until 2009, FAPAS® has organised seven plant health proficiency tests that covered the identification of lyophilised bacteria, viruses in leaves and fungi in agar plugs. In 2009, FAPAS® organized over 10 plant health proficiency tests under the banner of ‘PhytoPAS’, including Potato spindle tuber viroid, Phytophthora ramorum, Thrips palmi, Erwinia amylovora, Clavibacter michiganensis subsp. sepedonicus, etc. DNA extracts, cyst nematodes (Globodera pallida) and slides/immunofluorescence (IF) slides have been added to the programme. The organization of the plant health proficiency tests follows a similar pattern. Suitable test materials are prepared and tested for quality before distribution to requesting participants. Laboratories usually have 1–2 months to analyze their samples and return their results. A report is then compiled for issue to laboratories and these contain all results in an anonymous form, so that laboratories can compare their results with those of other participants. If a laboratory’s performance is unsatisfactory then it is up to them to investigate the situation. Thus, the primary purpose of PT is the detection of inaccuracy in a laboratory’s results, so that they can investigate the problems and initiate corrective procedures.

Block Designs in Method Transfer Experiments

Method transfer is a part of the pharmaceutical development process in which an analytical (chemical) procedure developed in one laboratory (typically the research laboratory) is about to be adopted by one or more recipient laboratories (production or commercial operations). The objective is to show that the recipient laboratory is capable of performing the procedure in an acceptable manner. In the course of carrying out a method transfer, other questions may arise related to fixed or random factors of interest, such as analyst, apparatus, batch, supplier of analytical reagents, and so forth. Estimates of reproducibility and repeatability may also be of interest. This article focuses on the application of various block designs that have been found useful in the comprehensive study of method transfer beyond the laboratory effect alone. An equivalence approach to the comparison of laboratories can still be carried out on either the least squares means or subject-specific means of the laboratories to justify a method transfer or to compare analytical methods.

HUPO BPP pilot study: A proteomics analysis of the mouse brain of different developmental stages

This study is a part of the HUPO Brain Proteome Project (BPP) pilot study, which aims at obtaining a reliable database of mouse brain proteome, at the comparison of techniques, laboratories, and approaches as well as at preparing subsequent proteome studies of neurologic diseases. The C57/Bl6 mouse brains of three developmental stages at embryonic day 16 (E16), postnatal day 7 (P7), and 8 wk (P56) (n = 5 in each group) were provided by the HUPO BPP executive committee. The whole brain proteins of each animal were individually prepared using 2-DE coupled with PDQuest software analysis. The protein spots representing developmentally related or stably expressed proteins were then prepared with in-gel digestion followed with MALDI-TOF/TOF MS/MS and analyzed using the MASCOT search engines to search the Swiss-Prot or NCBInr database. The 2-DE gel maps of the mouse brains of all of the developmental stages were obtained and submitted to the Data Collection Centre (DCC). The proteins alpha-enolase, stathmin, actin, C14orf166 homolog, 28,000 kDa heat- and acid-stable phosphoprotein, 3-mercaptopyruvate sulfurtransferase and 40 S ribosomal protein S3a were successfully identified. A further Western blotting analysis demonstrated that enolase is a protein up-regulated in the mouse brain from embryonic stage to adult stage. These data are helpful for understanding the proteome changes in the development of the mouse brain.

HUPO Brain Proteome Project: Summary of the pilot phase and introduction of a comprehensive data reprocessing strategy

The Human Proteome Organisation (HUPO) initiated several projects focusing on the proteome analysis of distinct human organs. The Brain Proteome Project (BPP) is the initiative dedicated to the brain, its development and correlated diseases. Two pilot studies have been performed aiming at the comparison of techniques, laboratories and approaches. With the help of the results gained, objective data submission, storage and reprocessing workflow have been established. The biological relevance of the data will be drawn from the inter-laboratory comparisons as well as from the re-calculation of all data sets submitted by the different groups. In the following, results of the single groups as well as the centralised reprocessing effort will be summarised and compared, showing the added value of this concerted work.

A Comparison of Instruments and Laboratories Used to Measure Milk Urea Nitrogen in Bulk-Tank Milk Samples

The objective of this study was to compare the instruments and laboratories that are currently used for analysis of milk urea nitrogen (MUN) for bulk-tank milk samples. Two replicate samples from each bulk tank on 10 different dairy farms were sent to 12 Dairy Herd Improvement Association (DHIA) laboratories throughout the US for MUN analysis. Two laboratories used 2 different methods for MUN analysis for a total of 14 analyses on 20 samples (n = 280). Values of MUN were analyzed using a random effects model with farm, laboratory, and farm×laboratory variance components. Greater than 98% of the variance in measured MUN was attributed to farm-to-farm variance for analysis of MUN by the Bentley, CL 10, Foss 6000, and Skalar instruments. However, for the laboratories using the Foss 4000 system, <60% of the variance in MUN was attributed to farm-to-farm variance. Laboratories using the Bentley, CL 10, Foss 6000, and Skalar instruments provided slightly different results for MUN analysis, but >95% of sample measurements fell within 1.75 mg/dL of each other. The laboratories using Foss 4000 differed from each other, and 95% of samples fell within 5 mg/dL of the CL 10 measurement. Laboratories using the Foss 4000 instrument did not consistently provide measurements of MUN that were similar to each other or to the measurements of the other instruments.

Incidence of Atypical Glandular Cells of Uncertain Significance in Cervical Cytology Following Introduction of the Bethesda System

Objective.To establish the frequency of the atypical glandular cells of uncertain significance (AGCUS) category, and its subcategories, as defined by the Bethesda System (TBS).Methods.Our computerized records of cervical/vaginal cytology specimens submitted from January 1, 1993, through December 31, 1995, were retrospectively reviewed for specimens diagnosed as AGCUS. When appropriate, our subcategory of “AGCUS favor premalignant/malignant lesion” was further qualified as “favor endocervical adenocarcinomain situ” or “suspicious for endometrial carcinoma.” The number of specimens and patients diagnosed for each subcategory were grouped by calendar year. Differences in frequency between time periods were tested for statistical significance using χ2analysis.Results.AGCUS was diagnosed in 1181 of 177,715 submitted specimens (0.66%). The frequency of subcategories was as follows: “favor reactive” (65%), “unable to further classify” (30%), “favor premalignant/malignant” (2.9%), “suspicious for endometrial carcinoma” (1.9%), and “favor endocervical adenocarcinomain situ” (0.4%). From 1993 to 1995 there was an increase in the rate of diagnosis of AGCUS (0.55 to 0.73%;P< 0.001) and a decrease in the percentage of specimens with AGCUS subclassified as “favor premalignant/malignant” (6.2 to 0.5%;P< 0.001). Other subcategories showed no significant change in frequency over this time period. The rate of biopsy-proven preinvasive or invasive lesions in AGCUS patients also showed no significant change from year to year over this time period.Conclusion.The AGCUS diagnosis can be anticipated at a low but consistent rate from a cytology laboratory using TBS. Any comparison of laboratories should take into consideration the change in reporting frequencies that occurs as part of the “learning curve” following introduction of TBS reporting. Uniform diagnostic criteria and additional reports with large numbers of cytologic specimens will be needed to establish the expected frequency of AGCUS and its subcategories.

Research on Learning

Research on Learning

Comparison of commercial pyrogen testing laboratories

The pyrogen test results of four laboratories were compared to determine if any inconsistencies existed. Samples submitted for pyrogen testing were of two types: (1) radiopharmaceuticals which had been allowed to decay to negligible activity or mock radiopharmaceuticals prepared with saline instead of pertechnetate, and (2) positive controls of bacterial endotoxin. The drugs used in the eight-rabbit tests included 99mTc-macroaggregated albumin, 99mTc-human serum albumin, 99mTc-sulfur colloid, saline and iodinated fibrinogen. Laboratory A showed a 52% failure rate for the testing of 36 preparations. Samples identical to those not passed by laboratory A were passed by laboratories B, C and D. It is recommended that all users of pyrogen testing laboratories periodically submit samples of known apyrogenicity for testing.

Interlaboratory comparison of university hospital referee laboratories and community hospital laboratories, using results of the 1968 College of American Pathologists clinical chemistry survey.

Copeland, Bradley E., Skendzel, Laurence P., and Barnett, Roy N.: Interlaboratory comparison of university hospital referee laboratories and community hospital laboratories, using results of the 1968 College of American Pathologists clinical chemistry survey. Am. J. Clin. Pathol. 58: 281–296, 1972. The performances of 58 to 112 university hospital laboratories and 1,300 to 1,700 clinical laboratories participating in the 1968 College of American Pathologists Comprehensive Clinical Chemistry Survey were compared. Each laboratory received eight identical lyophilized samples which were analyzed for eight to 12 chemical constituents. Although the university hospitals performed better, as would be expected, the difference from other laboratories was small. The ± 2 SD “state of the art” criterion used to evaluate performance in national surveys was found to be valid because it provides equally narrow or narrower ranges than those provided by the 99.73% range (3 SD) of university hospitals. Certain systematic differences were observed: these included (1) participant values too high for low sodium levels and too low for high sodium levels; (2) participant values too high for cholesterol and too low for uric acid. The findings indicate a need for particular attention to causes of mferlaboratory variability, which are shown to contribute a significantly greater amount than intralaboratory variability to the total variability of clinical chemical analyses of identical survey samples.