Multicenter evaluation of a new 4th generation HIV screening assay Elecsys HIV combi

Fourth-generation screening assays which permit a simultaneous detection of human immunodeficiency virus (HIV) antigen and antibody reduce the diagnostic window on average by four days in comparison to third-generation antibody assays. Recently, the new automated Elecsys HIV combi was compared in a multicenter study to alternative fourth- and third-generation assays, p24 antigen test and HIV-1 RNA RT-PCR. A total of 104 serocon-version panels, samples of the acute phase of infection after seroconversion (n = 33), anti-HIV-1 positive specimens (n = 572) from patients in different stages of the disease, 535 subtyped samples from different geographical locations, including group M (subtypes A-J) and group O, anti-HIV-2 positive sera (n = 364), dilutions of cell culture supernatants (n = 60) infected with different HIV-1 subtypes, selected performance panels, 8406 unselected samples from blood donors originating from different blood transfusion centers, 3810 unselected sera from daily routine and from hospitalized patients, 9927 unselected samples from South Africa and 1943 potentially interfering samples were tested with the Elecsys HIV combi. Elecsys HIV combi showed a comparable sensitivity to HIV-1 Ag stand-alone assays for early detection of HIV infection in seroconversion panels. The mean time delay of Elecsys HIV combi (last negative sample + 1 day) in comparison to HIV-1 RT-PCR for 92 panels tested with both methods was 3.23 days. The diagnostic window was reduced with Elecsys HIV combi between 1.56 and 5.32 days in comparison to third-generation assays. The specificity of Elecsys HIV combi in blood donors was 99.80% after repeated testing. Our results show that a fourth-generation assay with improved specificity and sensitivity like the Elecsys HIV combi is suitable for blood donor screening due to its low number of false positives and since it detects HIV p24 antigen with a comparable sensitivity to single antigen assays.     

Long-time quality assessment of the Elecsys Troponin T hs assay

Recently, Roche announced a problem with the calibrators for their high sensitive cardiac troponin T (hscTnT) assay. We have monitored the performance of the assay since its introduction into clinical use in December 2009 and we're in a unique position to provide quantitative information concerning the effects of this problem. Our data document that the measured cTnT concentration in the hscTnT assay dropped by 5.8 ng/L around the 99th percentile before its recalibration in May 2012. Thus, the hscTnT levels in our hospital have been underestimated around this cut-off value since its introduction. The approach we used may be one that other laboratories should consider.     

Clinical diagnosis and outcomes for Troponin T ‘positive’ patients assessed by a high sensitivity compared with a 4th generation assay

Background: High sensitivity troponin T (hsTnT) detects lower levels of troponin T with greater precision than the 4th generation (cTnT) assay. However, the clinical implications of this are uncertain. Objectives: Primary: Describe the proportion of patients who test ‘positive’ with hsTnT but negative with cTnT. Secondary: Determine proportion in each group with an adverse event (representation, AMI or died) within 90 days of the index test. Method: 161 patients samples were tested with cTnT and hsTNT assays. McNemar's test was used to compare paired samples. Electronic medical records were reviewed, with discharge diagnosis and 90 day outcomes determined blind to hsTnT results. Patients were then classified as ‘TnT negative’ (hsTnT was <0.014 mcg/mL), ‘new positive’ (hsTnT was ≥0.014 mcg/mL and cTnT <0.03 mcg/mL) and ‘TnT positive’ (cTNT was ≥0.03 mcg/mL). Results: Positive results more than doubled with the hsTnT assay (50% vs 22%, P < 0.001). 81 patients were ‘TnT negative’, 44 were ‘new positive’ and 36 ‘cTnT positive’. The discharge diagnosis for ‘new positives’ was AMI in 4 (9%), other cardiac in 13 (30%) and non‐cardiac in 27 (61%). At 90 days adverse events occurred in 30%, 54% and 50% of the groups respectively. There were no late cases of AMI or cardiovascular death in ‘new positive’ patients. Conclusion: Many patients with diagnoses other than AMI will have hsTNT above the reference level. Indiscriminate testing with hsTnT might lead to more patients requiring serial troponin testing and/or invasive further tests, which will have process and resource implications for EDs and health services.     

Multicenter analytical performance evaluation of the Elecsys proBNP assay.

The purpose of this multicenter study was to evaluate the technical performance of the automated Elecsys proBNP (brain natriuretic peptide) assay, which is indicated as an aid in the diagnosis of individuals suspected of having congestive heart failure. The Elecsys proBNP assay is an electrochemiluminescent immunoassay employing two polyclonal NT-proBNP-specific antibodies in a sandwich test format. The study was performed on the three Elecsys analyzers (E 1010, E 2010, and E 170) at eight different sites world-wide. Within- and total precision were < or = 3%, with total precision slightly higher on the Elecsys E 170 instrument with multiple modules. Reproducibility among sites and platforms was < 5%. Precision at particularly low NT-proBNP concentrations was assessed down to approximately 25 pg/ml with CVs of 12.6% at 29.2 pg/ml and 9.6% at 38.5 pg/ml for the Elecsys 1010/2010 and E 170, respectively. Linearity was evaluated up to 25,000 pg/ml with a sample-based non-linear response observed with recoveries of < 90% for proBNP concentrations < 10,000 pg/ml. Slopes ranged between 0.92 and 1.02 and intercepts from -5.3 to 10.4 pg/ml (r > or = 0.998) among the three types of analyzers. Slopes were 4.95 and 4.53 in comparison to the Biosite Triage and Shionogi BNP assays. There was no assay interference, and no effect of barrier gels, tube composition, or freeze-thaw. NT-proBNP concentrations in EDTA plasma were up to 10% lower than in serum or heparinized plasma and the analyte was stable at 4 degrees C for up to 72 hours (the maximum time tested). There was no circadian rhythm in normal subjects or congestive heart failure patients and there was no effect of drawing position. In summary, the Elecsys proBNP assay exhibits good technical performance and is suitable for use in routine clinical laboratories to aid in the diagnosis of congestive heart failure.     

Clinical evaluation of the Elecsys beta-CrossLaps serum assay, a new assay for degradation products of type I collagen C-tlopeptides

BACKGROUND: The Elecsys beta-CrossLaps serum assay measures type I collagen degradation fragments (beta-CTx) that contain the beta-isomerized octapeptide EKAHD-beta-GGR. We investigated the analytical performance of the assay and changes in beta-CrossLaps in patients with metabolic bone diseases. METHODS: The electrochemiluminescent sandwich immunoassay uses two monoclonal antibodies directed against different regions of the linear EKAHD-beta-GGR. RESULTS: beta-CrossLaps (beta-CTx) immunoreactivity was stable in serum and plasma stored at 4 degrees C for 24 h or at room temperature for 4 h, and it did not decrease appreciably in samples stored at -30 degrees C for 12 weeks. Nine cycles of repeated freezing-thawing did not affect serum beta-CTx. The intra- and interassay imprecision (CVs) for four samples was < or = 2.6% (n = 10) and < or = 4.1% (n = 10), respectively. The mean day-to-day biological variation (CV) was 20% in 10 postmenopausal women (n = 10 days). Serum beta-CTx and osteocalcin were correlated in patients with hyperparathyroidism (r = 0.796; P <0.0001; n = 28), chronic renal failure on hemodialysis (r = 0.784; P = 0.0003; n = 16), hypoparathyroidism (r = 0.950; P = 0.0001; n = 11), and pseudohypoparathyroidism (r = 0.987; P = 0.130; n = 4). Serum beta-CTx decreased by 47.4% +/- 8.8% (mean +/- SD) and 60.7% +/- 6.5% at 3 and 6 months, respectively, after initiation of estrogen replacement therapy in 34 women. These decreases were greater than the decreases in urinary excretion of deoxypyridinoline (31.8% +/- 3.9% and 38.1% +/- 4.4%, respectively) or pyridinoline cross-linked C-terminal telopeptide of type I collagen (15.9% +/- 3.9% and 16.9% +/- 4.6%, respectively). CONCLUSIONS: The Elecsys beta-CrossLaps serum assay provides a potentially useful tool for assessing bone resorption state, including its response to estrogen replacement therapy.     

A multicenter performance evaluation of the new Elecsys Vitamin D total III assay versus reference isotope dilution liquid chromatography tandem mass spectrometry and commercially available comparators

BackgroundVitamin D deficiency/insufficiency and toxicity are worldwide issues; thus, accurate diagnostic assays are required to measure vitamin D. We evaluated the performance of the new Elecsys^® Vitamin D total III assay (Roche Diagnostics International Ltd).MethodsRepeatability and intermediate precision of the Elecsys Vitamin D total III assay (cobas e 601 analyzer) were evaluated at three sites using five human serum pools (HSPs) and two PreciControls (five‐day model, one reagent lot [CLSI‐EP05‐A3]) and compared against prespecified acceptance criteria. A serum verification panel, with reference isotope dilution liquid chromatography tandem mass spectrometry (ID‐LC–MS/MS) values, was used for comparator assay/concordance studies at two sites, assessed using unweighted Deming regression. Testing of serum vs. plasma on the Elecsys assay was conducted at one site using samples from healthy adults; assessed using Passing‐Bablok regression.ResultsRepeatability (HSP1 [16.8–18.4 ng/ml], SD 0.87–1.07; HSP5 [94.5–98.0 ng/ml], CV 1.58%–2.76%) and intermediate precision (HSP1, SD 1.14–1.77; HSP5, CV 2.00%–4.13%) met acceptance criteria across sites. Agreement was observed between the Elecsys assay and (i) the ID‐LC–MS/MS verification panel (slope, 0.936–1.01; Pearson''s r, 0.960–0.986) and (ii) comparator assays (slope, 0.921–1.15; Pearson''s r, 0.958–0.982). The Elecsys assay correctly assigned the highest combined percentage of samples to deficient (100%) and insufficient (89.5%) vitamin D categories vs. comparator assays and demonstrated comparable performance in serum and plasma (y = 0.103 + 0.984x).ConclusionsThe Elecsys Vitamin D total III assay demonstrated good analytical performance and compared favorably with other assays, supporting its use in clinical practice.     

Multicenter analytical evaluation of a high-sensitivity troponin T assay

BackgroundHigh-sensitivity cardiac troponin assays are being introduced clinically for earlier diagnosis of acute myocardial infarction (AMI). We evaluated the analytical performance of a high-sensitivity cardiac troponin T assay (hscTnT, Roche Diagnostics) in a multicenter, international trial.MethodsThree US and 5 European sites evaluated hscTnT on the Modular® Analytics E170, cobas® 6000, Elecsys 2010, and cobas® e 411. Precision, accuracy, reportable range, an inter-laboratory comparison trial, and the 99th percentile of a reference population were assessed.ResultsTotal imprecision (CVs) were 4.6–36.8% between 3.4 and 10.3 ng/L hscTnT. Assay linearity was up to 10,000 ng/L and the limit of blank and detection were 3 and 5 ng/L, respectively. The 99th percentile reference limit was 14.2 ng/L (n = 533). No significant differences between specimen types, assay incubation time, or reagent lots existed. A substantial positive bias (76%) exists between the 4th generation and hscTnT assays at the low end of the measuring range (< 50 ng/L). hscTnT serum pool concentrations were within 2SD limits of the mean of means in the comparison trial, indicating comparable results across multiple platforms and laboratories.ConclusionThe Roche hscTnT assay conforms to guideline precision requirements and will likely identify additional patients with myocardial injury suspicious for AMI.     

第3代TRAb测定(Elecsys)对甲状腺毒血症的鉴别诊断价值

目的： 探讨第3代促甲状腺素受体抗体（TRAb）检测方法——电化学发光法（Elecsys）对甲状腺毒血症病因鉴别的诊断价值。方法： 回顾性选取2016年1月至2018年5月复旦大学附属华山医院收治的未经治疗的甲状腺毒血症患者154例，测定其甲状腺功能、TRAb、甲状腺摄碘率和甲状腺上动脉收缩期峰值流速（peak systolic velocity of superior thyroid artery，STA-PSV）。采用ROC曲线比较第3代TRAb及STA-PSV对Graves病（Graves''disease，GD）和破坏性甲状腺炎（destructive thyroiditis，DT）的鉴别诊断价值。结果： 154例甲状腺毒血症患者中，女性111例（72.0%），平均年龄38.42岁，GD 117例（76.0%）。TRAb的AUC为0.984（95% CI 0.967~1.000），优于STA-PSV （AUC 0.903，95% CI 0.839~0.967）。TRAb的最佳切割点为1.7 U/L，区分GD和DT的灵敏度和特异度为94.8%和94.3%。TRAb切割点为3.6 U/L时，其鉴别GD/DT的特异度和阳性预测值均为100%。结论： 第3代TRAb检测（Elecsys）对甲状腺毒症的病因鉴别具有较高的灵敏度和特异度。     

Analytical and clinical performance of a detergent-based homogeneous LDL-cholesterol assay: a multicenter evaluation

BACKGROUND: LDL-cholesterol (LDL-C) concentrations currently are determined in most clinical laboratories using the Friedewald calculation. This approach has several limitations and may not always meet the current total error recommendation in LDL-C measurement of 相似文献   

Results of a multicenter evaluation of enzyme immunoassays for thyrotropin (TSH)

This paper summarises the results of the evaluation of an enzyme immunoassay for thyrotropin by a group of 17 laboratories. This sandwich enzyme immunoassay is based on the specific binding of the beta-subunit of thyrotropin by monoclonal antibodies coated on polystyrene tubes. Thyrotropin, bound to the tube wall, is determined with horse radish peroxidase coupled to the Fab fragment of a polyclonal sheep antibody against the alpha-subunit of thyrotropin. The lower limit of detection of 0.5 mU/1 was adequate, and the precision of the enzyme immunoassay was comparable with that found in radioimmunoassays for thyrotropin. The intraassay CV was in the range of 2 to 10% for a serum containing 1.5 to 5 mU/1 thyrotropin. The interassay CV was in the range of 5 to 10% for a serum containing about 6 mU/1. The recovery of thyrotropin standards in human thyrotropin-free serum was between 93% and 101%. Cross-reactions with human choriongonadotropin and gonadotropins were excluded. There were no interferences in haemolytic and lipaemic samples or by high bilirubin concentrations. Comparison of thyrotropin levels measured with different radioimmunoassays and with the enzyme immunoassay gave correlation coefficients in the range of 0.925 and 0.995. Advantages of the enzyme immunoassay are the absence of radioactive substances and the short incubation period of 3 hours. Incubation overnight results in a higher sensitivity of 0.18 mU/1. This assay can therefore be regarded as one of the new highly sensitive thyrotropin assays (Bernutz, C. et al. (1985) Clin. Chem. 31, 289-292).     

Analytic evaluation of the beta-human chorionic gonadotropin assay on the Abbott IMx and Elecsys2010 for its use in doping control

OBJECTIVES: The principal objective of this study was to compare the analytical performance of the Elecsys2010 (Roche Diagnostics) system with the IMx (Abbott laboratories) system for beta-hCG assay in order to assess its possible utility as a confirmation test for the quantitative measurement of beta-hCG in urine for doping control purposes. DESIGN AND METHODS: Urine samples with spiked standard known concentrations of beta-hCG and different urine samples from athletes were used in order to determine the calibration curve stability and linearity, detection limit, total, within-run and between-run precision, and method comparison for the IMx and Elecsys2010 systems for beta-hCG assay, along with the stability of samples, at room temperature and at 4 degrees C. RESULTS: The IMx assay was linear up to 500 IU/L, whereas the Elecsys2010 assay was linear up to 1000 IU/L. The detection limit for the IMx and Elecsys2010 systems were 0.75 IU/L and 0.25 IU/L, respectively. The total precision of the IMx and Elecsys2010 systems were 相似文献   

肌钙蛋白I与肌钙蛋白T敏感性的比较和分析

目的 评价和分析心肌肌钙蛋白I（cTnI）和肌钙蛋白T（cTnT）在临床实验诊断中的敏感性差异.方法 对109例患者的同一血清标本用全自动化学发光免疫分析仪和全自动电化学发光分析仪两种不同的设备及方法来分别检测肌钙蛋白I和肌钙蛋白T,对肌钙蛋白T阴性的患者4小时～3天内进行肌钙蛋白T跟踪检测,再把其结果进行统计、对比与分析.结果 对定量检测109例肌钙蛋白I的阳性血清样本中,肌钙蛋白T只有57例显示为阳性 52例肌钙蛋白T阴性的患者跟踪检测中,有17例为阳性.结论 肌钙蛋白I比肌钙蛋白T的敏感度要高,肌钙蛋白I能更早地反映心肌组织损害.     

Analytical evaluation of an automated immunoassay for cardiac troponin I: the Vidas Troponin I assay.

Cardiac troponin I (cTnI) is a sensitive and specific biochemical marker of myocardial damage. We assessed the analytical performance of the Vidas Troponin I assay (Biomerieux). Controls and serum pools were used to determine the precision, analytical sensitivity and linearity; 97.5 and 99.5 percentiles concentrations were determined from the reference population. Fifty corresponding samples of serum and plasma (lithium-heparin) were tested and the results compared. The in vitro stability of serum and plasma samples was assessed at 20 degrees C, 4 degrees C and -20 degrees C, respectively. Samples of serum were used to assess the agreement between the Vidas Troponin I method and the revised Dimension RxL cTnI method (Dade-Behring). The total imprecision (CVs) was 13.1-5.2% for concentrations ranging between 0.25 and 19.8 microg/l cTnI. The lower detection limit was <0.1 microg/l. The upper reference limit (97.5 and 99.5 percentiles) was 0.11 microg/l and 0.12 microg/l, respectively (CV > 10%). The assay was linear up to 21 microg/l. The concentrations in lithium-heparin plasma were higher compared to those of the matched serum samples. The study of the agreement between the Vidas and Dimension RxL cTnI assays showed a total concordance of 96% with a bias value of -0.042. The Vidas Troponin I test is a fast, precise and sensitive method for the determination of cTnI.     

第3代促甲状腺素受体抗体测定法(Elecsys)对甲状腺毒血症的鉴别诊断价值

目的:探讨第3代促甲状腺素受体抗体(TRAb)检测方法——电化学发光法(Elecsys)对甲状腺毒血症病因鉴别的诊断价值.方法:回顾性选取2016年1月至2018年5月复旦大学附属华山医院收治的未经治疗的甲状腺毒血症患者154例,测定其甲状腺功能、TRAb、甲状腺摄碘率和甲状腺上动脉收缩期峰值流速(peak systo...     

Effect of hemolysis on cardiac troponin T determination by the Elecsys 2010 immunoanalyzer

OBJECTIVE: To evaluate the effect of hemolysis on the measurement of cardiac troponin T (cTnT) using the Elecsys 2010 immunoanalyzer. METHODS: cTnT concentrations were measured using the Elecsys 2010. Interference studies were conducted by mixing serum of known cTnT concentration with either hemolysates or serum to which purified hemoglobin (Hgb) had been added. Hemolysates were prepared by mechanical disruption. PROBIT analysis was conducted to determine the probability of a cTnT result of >0.1 microg/l being decreased to <0.1 microg/l due to hemoglobin interference. RESULTS: Purified hemoglobin as well as serum-hemolysates mediated a concentration-dependent inhibition of cTnT determination with the Elecsys 2010. With every 1 g/l increase in hemoglobin, the probability of cTnT >0.1 is decreased by 2.5%. CONCLUSIONS: A concentration-dependent negative bias in the measurement of cTnT is associated with increasing hemoglobin concentrations in serum.