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Giavarina D.,Clinical Chemistry and Hematology Laboratory
Biochemia Medica | Year: 2015

In a contemporary clinical laboratory it is very common to have to assess the agreement between two quantitative methods of measurement. The correct statistical approach to assess this degree of agreement is not obvious. Correlation and regression studies are frequently proposed. However, correlation studies the relationship between one variable and another, not the differences, and it is not recommended as a method for assessing the comparability between methods. In 1983 Altman and Bland (B&A) proposed an alternative analysis, based on the quantification of the agreement between two quantitative measurements by studying the mean difference and constructing limits of agreement. The B&A plot analysis is a simple way to evaluate a bias between the mean differences, and to estimate an agreement interval, within which 95% of the differences of the second method, compared to the first one, fall. Data can be analyzed both as unit differences plot and as percentage differences plot. The B&A plot method only defines the intervals of agreements, it does not say whether those limits are acceptable or not. Acceptable limits must be defined a priori, based on clinical necessity, biological considerations or other goals. The aim of this article is to provide guidance on the use and interpretation of Bland Altman analysis in method comparison studies. © 2015, Croatian Society of Medical Biochemistry and Laboratory Medicine. Source


Van Rossum H.H.,Clinical Chemistry and Hematology Laboratory | Faix J.D.,Stanford University | Shi R.Z.,Stanford University
Nederlands Tijdschrift voor Klinische Chemie en Laboratoriumgeneeskunde | Year: 2012

Analysis of testosterone is helpful for investigation of several conditions such as hypogonadism or limited testis function in man, hirsutism hyperandrogenism or polycystic ovarian syndrome in women, and early or late onset of puberty in boys. Unfortunately the analytical performance of the commonly used testosterone immunoassays is limited in terms of sensitivity and specificity for analysis of low testosterone concentrations that are normally found in females and children. Since improved sensitivity and specificity in the low testosterone concentration range has been reported for testosterone assays using liquid chromatography tandem mass spectrometry (LC-MS/MS), we intended to set-up such an assay (1-5). Our goal was to develop a method applicable for routine testing, and although methods that utilize testosterone derivatization generally result in even higher testosterone assay sensitivity, we choose to avoid derivatization in order to simplify sample preparation. Source


Favaloro E.J.,ICPMR | Dorothy M.,Esoterix Inc | Lippi G.,Clinical Chemistry and Hematology Laboratory
Laboratory Medicine | Year: 2012

The use of modern laboratory instrumentation with high levels of test reliability and appropriate quality assurance measures will lead to very few analytical errors within hemostasis testing. Nevertheless, incorrect or inappropriate test results are still reported, often due to events outside the control of the laboratories performing the tests. This is due primarily to pre-analytical events associated with sample collection and processing, as well as post-analytical events related to the reporting and interpretation of test results. This review focuses on the pre-analytical phase, highlighting contributory elements and providing suggestions on how problems can be minimized or prevented, thereby improving the likelihood that reported test results actually represent the true clinical status of the patient rather than that of an inappropriate sample. This review should be of value to both laboratory personnel and clinicians because an appreciation of these issues will enable the optimal clinical management of patients. © 2012 by The American Society for Clinical Pathology. Source


Lippi G.,Clinical Chemistry and Hematology Laboratory | Plebani M.,University of Padua
Journal of Laboratory Automation | Year: 2013

A paradigm shift has occurred in the role and organization of laboratory diagnostics over the past decades, wherein consolidation or networking of small laboratories into larger factories and point-of-care testing have simultaneously evolved and now seem to favorably coexist. There is now evidence, however, that the growing implementation of continuous-flow automation, especially in closed systems, has not eased the identification of hemolyzed specimens since the integration of preanalytical and analytical workstations would hide them from visual scrutiny, with an inherent risk that unreliable test results may be released to the stakeholders. Along with other technical breakthroughs, the new generation of laboratory instrumentation is increasingly equipped with systems that can systematically and automatically be tested for a broad series of interferences, the so-called serum indices, which also include the hemolysis index. The routine implementation of these technical tools in clinical laboratories equipped with continuous-flow automation carries several advantages and some drawbacks that are discussed in this article. © 2012 Society for Laboratory Automation and Screening. Source


Tampoia M.,University of Bari | Giavarina D.,Clinical Chemistry and Hematology Laboratory | Di Giorgio C.,University of Bari | Bizzaro N.,Laboratory of Clinical Pathology
Autoimmunity Reviews | Year: 2012

Background: Systematic reviews and meta-analysis are essential tools to accurately and reliably summarize evidence, and can be used as a starting point for developing practice guidelines for the diagnosis and treatment of patients. Aim: To estimate the diagnostic accuracy of enzyme-linked immunosorbent assays (ELISA) to detect anti-BP180 and anti-desmoglein 3 (Dsg3) autoantibodies in the diagnosis of autoimmune blistering skin diseases. Methods: A Medline search of English written articles, published between 1994 and 2011, reporting data on the sensitivity and specificity of diagnostic tests was conducted using the following search terms: "BP180 autoantibodies", "Dsg3 autoantibodies", and "enzyme linked immunosorbent assay". The selected articles have been evaluated according to the quality of the statistical methods used to calculate diagnostic accuracy (definition of cutoff value, use of ROC curves, and selection of control cases). The meta-analysis was performed using a summary ROC (SROC) curve and a random-effect model to independently combine sensitivity and specificity across studies. Results: The search yielded 69 publications on BP180 autoantibodies and 178 on Dsg3 autoantibodies. A total of 30 studies met the inclusion criteria: 17 provided data on the assays to detect autoantibodies to BP180 in a sample of 583 patients with bullous pemphigoid (BP), while 13 studies provided data on the assays to search for anti-Dsg3 autoantibodies in a sample of 1058 patients with pemphigus vulgaris (PV). The 17 studies on BP180 autoantibodies yielded a pooled sensitivity of 0.87 (95% confidence interval (CI) 0.85 to 0.89) and a pooled specificity of 0.98 (CI, 0.98 to 0.99). The area under the curve (AUC) for the SROC curve was 0.988, and the summary diagnostic odds ratio was 374.91 (CI, 249.97 to 562.30). The 13 studies on Dsg3 autoantibodies which met the inclusion criteria, yielded a pooled sensitivity of 0.97 (CI, 0.95 to 0.98), and a pooled specificity of 0.98 (CI, 0.98 to 0.99). The AUC for the SROC curve was 0.995 and the summary diagnostic odds ratio was 1466.11 (95% CI, 750.36 to 2864.61). Conclusions: Results of the meta-analysis demonstrated that ELISA tests for anti-BP180 and anti-Dsg3 autoantibodies have high sensitivity and specificity for BP and PV, respectively, and can be used in daily laboratory practice for the initial diagnosis of autoimmune blistering skin diseases. © 2012 Elsevier B.V. Source

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