Harmonization of two hs-cTnI methods based on recalibration of measured quality control and clinical samples.

Background: The study aim was to evaluate whether is possible to harmonize the results of two hs-cTnI methods using a recalibration procedure based on linear regression models and measured values of external quality assessment (EQA) and clinical samples.

Methods: A two-step experimental approach was used. The preliminary step was performed using 16 EQA samples.

A Black Swan in clinical laboratory practice: the analytical error due to interferences in immunoassay methods.

It is well known that the results of immunoassay methods can be affected by specific or non-specific interferences, ranging from 0.4% to 4.0%.

Evaluation of analytical performance of a new high-sensitivity immunoassay for cardiac troponin I.

Background: The study aim was to evaluate and compare the analytical performance of the new chemiluminescent immunoassay for cardiac troponin I (cTnI), called Access hs-TnI using DxI platform, with those of Access AccuTnI+3 method, and high-sensitivity (hs) cTnI method for ARCHITECT platform.

Methods: The limits of blank (LoB), detection (LoD) and quantitation (LoQ) at 10% and 20% CV were evaluated according to international standardized protocols. For the evaluation of analytical performance and comparison of cTnI results, both heparinized plasma samples, collected from healthy subjects and patients with cardiac diseases, and quality control samples distributed in external quality assessment programs were used.

Pilot study on harmonization of cardiac troponin I immunoassays using patients and quality control plasma samples. On behalf of the Italian Section of the European Ligand Assay Society (ELAS) and of the Study Group on Cardiovascular Biomarkers of the Società Italiana di Biochimica Clinica (SIBioC).

Background: The aim of this study is to evaluate whether it is possible to reduce the between-methods variability of troponin I (cTnI) immunoassays using mathematical algorithms calculated from the results of both patients' samples and quality control materials distributed in an external quality assessment (EQA) scheme.

Methods: We collected 122 heparinized plasma samples of patients admitted to the emergency department with thoracic pain or supraventricular tachyarrhythmia. Moreover, we also analyzed 20 control samples distributed in an EQA and 26 plasma pools prepared from healthy subjects and patients with myocardial infarction.

Evaluation of analytical performance and comparison of clinical results of the new generation method AccuTnI+3 for the measurement of cardiac troponin I using both patients and quality control plasma samples.

The study aims are to evaluate the analytical performance and the clinical results of the chemiluminescent Access AccuTnI+3 immunoassay for the determination of cardiac troponin I (cTnI) with DxI 800 and Access2 platforms and to compare the clinical results obtained with this method with those of three cTnI immunoassays, recently introduced in the European market. The limits of blank (LoB), detection (LoD), and quantitation (LoQ) at 20% CV and 10% CV were 4.5 ng/L and 10.

State of the art of aldosterone immunoassays. A multicenter collaborative study on the behalf of the Cardiovascular Biomarkers Study Group of the Italian Section of European Society of Ligand Assay (ELAS) and Società Italiana di Biochimica Clinica (SIBIOC).

Background: Two new immunoassay methods for aldosterone assay using automated platforms recently became available into market. The main aim of the present study is to evaluate the analytical performance of these automated direct immunoassay methods, and also to compare their analytical characteristics to those of the most popular RIA and EIA methods used in an Italian External Quality Assessment (EQA) study.

Methods: In this study analytical performances of two aldosterone immunoassays using the IDS iSYS and DiaSorin LIAISON fully automated platforms, were evaluated.

Harmonization protocols for thyroid stimulating hormone (TSH) immunoassays: different approaches based on the consensus mean value.

The lack of interchangeable laboratory results and consensus in current practices has underpinned greater attention to standardization and harmonization projects. In the area of method standardization and harmonization, there is considerable debate about how best to achieve comparability of measurement for immunoassays, and in particular heterogeneous proteins. The term standardization should be used only when comparable results among measurement procedures are based on calibration traceability to the International System of Units (SI unit) using a reference measurement procedure (RMP).

State of the art of BNP and NT-proBNP immunoassays: the CardioOrmoCheck study.

To evaluate differences in analytical performance and clinical results of BNP and NT-proBNP immunoassays, a proficiency testing program, called CardioOrmoCheck study, has been organized since 2005 under the patronage of the Study Group of the Cardiovascular Biomarkers of the Italian Society of Clinical Biochemistry (SIBIOC). On average more than 100 Italian laboratories were involved in the annual 2005-2011 cycles. In total, 72 study samples were distributed and measured by participant laboratories for a total of 6706 results.

Multicentre comparison of free thyroid hormones immunoassays: the Immunocheck study.

Background: In order to evaluate whether there is still present a very large variability in measured values and analytical performance among different free thyroid (FT) hormone immunoassays, we considered the results derived from an External Quality Assessment (EQA) scheme, named Immunocheck.

Methods: The EQA Immonocheck study enrolled about 1000 participant laboratories, which measured the 54 quality control samples distributed in the three annual cycles (2007, 2008 and 2009). Participant laboratories produced a total of 30,476 results for FT3 and 31,351 for FT4, respectively.

Proficiency testing project for brain natriuretic peptide (BNP) and the N-terminal part of the propeptide of BNP (NT-proBNP) immunoassays: the CardioOrmocheck study.

Background: We organized and conducted a proficiency testing study (CardioOrmocheck) to evaluate the differences in analytical performance of brain natriuretic peptide (BNP) and N-terminal proBNP (NT-proBNP) immunoassays.

Methods: Approximately 90 Italian laboratories were involved in the 2005-2007 proficiency testing cycles, while 112 laboratories took part in the 2008 cycle (from January to May 2008). A total of 28 study samples were measured by participating laboratories for a total of 2354 determinations.

Comparison between analytical performances of polyclonal and monoclonal electrochemiluminescence immunoassays for NT-proBNP.

Background: We evaluated the analytical characteristics of electrochemiluminescence (ECLIA) immunoassay for NT-proBNP (proBNP II, Roche Diagnostics, Germany) and compared its analytical performance to that of the previous polyclonal method.

Methods: We measured NT-proBNP in EDTA plasma samples of 177 consecutive cardiac patients (69 females and 108 males; mean age 62.2+/-16.

Distribution of plasma cardiac troponin I values in healthy subjects: pathophysiological considerations.

Background: The aim of this study was to evaluate the distribution of cardiac troponin I (cTnI) values, measured by the ADVIA TnI-Ultra method (Siemens Medical Solutions Diagnostics SrL) in healthy subjects and to characterize its relation to gender, age, as well as to N-terminal fragment of pro-brain natriuretic peptide (NT-proBNP).

Methods: A Caucasian population of 692 healthy subjects (311 males and 381 females) with a mean (SD) age of 45.3 (17.

Gender-related differences in oxidative stress levels among elderly patients with coronary artery disease.

Objective: To evaluate whether gender-related differences exist concerning oxidative stress levels in aged patients with coronary artery disease (CAD).

Design: Case-control.

Setting: Clinical and research center.

Automation and validation of a fast method for the assessment of in vivo oxidative stress levels.

Background: The d-ROMs test for the evaluation of serum hydroperoxides (HP) is simple, reliable, and cheap. Furthermore, it can easily be adapted to automated analyzers. Changing from the manual to an automated procedure allows the simultaneous processing of a large number of samples in a greatly reduced time, avoiding manual handling of samples and reagents and reducing variability sources.

Evaluation of the analytical performance of the advanced method for cardiac troponin I for the AxSYM platform: comparison with the old method and the Access system.

Background: The determination of cardiac troponins is routinely used for rule in/out, risk stratification, and follow-up of patients with acute coronary artery syndrome. We evaluated the analytical and clinical performance of the advanced immunoassay for troponin I (cTnI) carried out on an AxSYM platform (Abbott Diagnostic Division) and compared these characteristics to those of the previous version of this assay and to cTnI on the Access 2 immunoassay system (Beckman Coulter, Inc.).

Clinical relevance of biological variation: the lesson of brain natriuretic peptide (BNP) and NT-proBNP assay.

The clinical relevance of brain natriuretic peptide (BNP) and N-terminal (NT)-proBNP assays as a diagnostic tool and prognostic marker in patients with cardiovascular diseases has recently been confirmed. However, several studies demonstrated variation of intra-individual BNP concentrations of >30% (ranging from 30% to 50%) with reference change values at the 95% confidence interval (i.e.

Estrogen therapy effects on different vasoactive factors in recent postmenopausal healthy women.

Background: To evaluate whether the route of estrogen therapy (ET) may affect the levels of different vasoactive factors in healthy recent post-menopausal women.

Methods: We conducted a cross-over study in 20 healthy nonsmoking women in recent postmenopause (1.8+/-0.

Usefulness of high-sensitivity IL-6 measurement for clinical characterization of patients with coronary artery disease.

Interleukin 6 (IL-6) may represent an early marker of inflammatory activation and may be useful to ameliorate risk stratification in patients with ischemic heart disease. The aim of this study was to verify the performance characteristics of an ultrasensitive immunoassay (Biosource International, Camarillo, CA) for high-sensitivity (hs)-IL-6 measurement in comparison with hs-R&D Systems (Abingdon, United Kingdom) and Immulite System (Diagnostic Products Corporation [DPC], Los Angeles, CA) methods in patients with ischemic heart disease. In addition, hs-C-reactive protein (hs-CRP) concentrations were measured, to evaluate the correlation with hs-IL-6 levels.