Evaluation of COVID-19 Antigen Test Kit Assay Analytical and Clinical Performance / 中国医疗器械杂志

Objective To rapidly screen patients with novel coronavirus pneumonia (COVID-19) infection including asymptomatic ones. Method Established a rapid detection test kit, and evaluated analytical and clinical performance of it. Result The minimum limit of detection of the reagent was 9.75×102 TCID50/mL; there was no cross-reaction and interference in the high-concentration samples of 29 common respiratory pathogens tested. The diagnostic sensitivity of clinical samples was 98.56%, specificity was 99.00%, and the total coincidence rate was 98.85%; the consistency test Kappa value is 0.974 5. The stratified analysis of positive samples with different Ct values showed that the coincidence rate within each stratum was greater than 95%. Conclusion This COVID-19 antigen test kit with excellent detection performance, fast detection speed, and portable operation. It can be used as a supplementary method for existing nucleic acid detection methods for early screening of new coronavirus.

Establishing allowable total error for serum total folate in external quality assessment / 中华检验医学杂志

Objective:To establish the allowable total error (TEa) of the national external quality assessment (EQA) program in line with the current quality level of serum folate measurement in China.Methods:The data of serum total folate test in the clinical laboratory of a hospital in Beijing in 2016 were collected, and the Stata SE 15 software was used for Monte Carlo simulation to obtain the false-negative rate under different bias and inaccuracy conditions. The Origin Pro 9.1 software was used to make the contour figure. The TEa of serum total folate test is derived based on the acceptable false-negative rate. National EQA data of serum total folate in 2020 were collected to calculate the pass rate of participating laboratories and the laboratory pass rate of quality control products at each level under the five TEa derived from the analysis performance on clinical outcomes, biological variation, and the evaluation criterion of national EQA.Results:Based on the influence of analytical performance on clinical outcomes, the TEa was 10%. Under this TEa, the pass rate of the first EQA program of serum total folate in 2020 was more than 80%, and the pass rate of the second time was 73.1%. Under the minimum (46.57%) and appropriate level of TEa (15.52%) derived from biological variation and national EQA evaluation criterion, the pass rate of serum total folate in the two EQA programs in 2020 exceeded 85%.Conclusion:The analytical performance of serum total folate in China cannot meet the requirements of TEa derived based on the effect of analytical performance on clinical outcomes. An appropriate level of TEa derived based on biological variation (15.52%) is suggested as the recommended criterion for the TEa of serum total folate test.

Performance Evaluation and Clinical Usefulness of α-fetoprotein Test Measured on Sysmex HISCL-5000

Evaluation of Analytical Performance of an Automated Glycated Hemoglobin Analyzer, HLC-723 G11

Performance Evaluation of Body Fluid Cellular Analysis Using the Beckman Coulter UniCel DxH 800, Sysmex XN-350, and UF-5000 Automated Cellular Analyzers

BACKGROUND: Automated cellular analyzers are expected to improve the analytical performance in body fluid (BF) analysis. We evaluated the analytical performance of three automated cellular analyzers and established optimum reflex analysis guidelines. METHODS: A total of 542 BF samples (88 cerebrospinal fluid [CSF] samples and 454 non-CSF samples) were examined using manual counting and three automated cellular analyzers: UniCel DxH 800 (Beckman Coulter), XN-350 (Sysmex), and UF-5000 (Sysmex). Additionally, 2,779 BF analysis results were retrospectively reviewed. For malignant cell analysis, the receiver operating characteristic (ROC) curve was used, and the detection of high fluorescence-BF cells (HF-BFs) using the XN-350 analyzer was compared with cytology results. RESULTS: All three analyzers showed good agreement for total nucleated cell (TNC) and red blood cell (RBC) counts, except for the RBC count in CSF samples using the UniCel DxH 800. However, variable degrees of differences were observed during differential cell counting. For malignant cell analysis, the area under the curve was 0.63 for the XN-350 analyzer and 0.76 for manual counting. We established our own reflex analysis guidelines as follows: HF-BFs 83.4/100 WBCs or eosinophils >3.8% are the criteria for mandatory double check confirmation with 1,000× magnification examination. CONCLUSIONS: The three automated analyzers showed good analytical performances. Application of reflex analysis guidelines is recommended for eosinophils and HF-BFs, and manual confirmation is warranted.

Performance Evaluation of the Beckman Coulter DxN VERIS Hepatitis B Virus (HBV) Assay in Comparison With the Abbott RealTime HBV Assay

The detection and quantification of hepatitis B virus (HBV) DNA plays an important role in diagnosing and monitoring HBV infection as well as in assessing the therapeutic response. We compared the analytical performance of a random access, fully automated HBV assay—DxN VERIS Molecular Diagnostics System (Beckman Coulter, Brea, CA, USA)—with that of Abbott RealTime HBV assay (Abbott Laboratories, Des Plaines, IL, USA). The between-day precision of the VERIS assay ranged from 0.92% (mean 4.68 log IU/mL) to 4.15% (mean 2.09 log IU/mL) for pooled sera from HBV patients. HBV DNA levels measured by the VERIS HBV assay correlated with the calculated HBV DNA levels (r²=0.9994; P < 0.0001). The lower limit of quantification was estimated as 8.76 IU/mL (Probit analysis, 95% confidence interval: 7.32–12.00 IU/mL). Passing-Bablok regression analysis showed good concordance between the VERIS and RealTime assays for 187 chronic HBV samples (y=−0.2397+0.9712x; r=0.981), as well as for 20 drug-resistant HBV genotype C positive samples (y=−0.5415+0.9954x; r=0.961). The VERIS assay demonstrated performance similar to the RealTime assay and is suitable for high-throughput HBV DNA monitoring in large hospital laboratories.

Estudio de estabilidad acelerado del diagnosticador HemoCen Aerobio / Accelerated stability study of the HemoCen Aerobic diagnostician

La bacteriemia es una complicación grave de las infecciones bacterianas. Un diagnóstico temprano del microorganismo responsable permite aplicar tratamientos efectivos en menor intervalo de tiempo. Los hemocultivos son diagnosticadores clínicos diseñado para este fin. Objetivo: Realizar un estudio de estabilidad acelerado de un lote del hemocultivo HemoCen Aerobio que permita planificar su diseño en estante en condiciones reales. Métodos: Se formuló un lote del hemocultivo HemoCen Aerobio en el Centro Nacional de Biopreparados, BioCen y se envasó asépticamente en los Laboratorios Biológicos Farmacéuticos, LABIOFAM. Se llevó a cabo un estudio de estabilidad acelerado por el Método de Arrenhius. Los frascos se conservaron durante 120 días a 15 °C, 30 °C y 50 °C. Se realizaron evaluaciones físico-químicas, organolépticas y capacidad de promoción de crecimiento de Staphylococcus aureus ATCC 25923 a los 7, 15, 30, 60 y 120 días. Resultados: El estudio de estabilidad demostró que el pH y el color del medio se deterioran progresivamente en el tiempo cuando las temperaturas aumentan entre 30 °C y 50 °C. La promoción de crecimiento de Staphylococcus aureus resultó favorable con índices de recuperación entre 20 y 40 UFC·frasco-1. Discusión: HemoCen Aerobio resulta funcional con un desempeño analítico satisfactorio, cuyos índices de recuperación microbiana se encuentran acorde a los valores reportados en bacteriemias de escasa magnitud. Estos resultados sientan las bases para planificar un estudio de estabilidad en estante en condiciones reales. Conclusión: Se estima un período de validez de 2 años(AU)

Bacteremia is a serious complication of bacterial infections. Early diagnosis of the causative organism allows applying appropriate treatments in a shorter time interval. Hemocultures are clinical diagnosticians designed for this purpose. Objective: Perform an accelerated stability study of a batch of HemoCen Aerobic hemoculture that allows planning its shelf designed in true conditions. Methods: A batch of HemoCen Aerobic hemoculture was formulated at the National Bioproducts Center, BioCen, and aseptically packaged at the Biological Pharmaceutical Laboratories, LABIOFAM. An accelerated stability study was carried out by the Arrenhius Method. The bottles were stored for 120 days at 15 °C, 30 °C and 50 °C. Physicochemical, organoleptic and growth promotion capacity evaluations of Staphylococcus aureus ATCC 25923 were realized at 7, 15, 30, 60 and 120 days. Results: The stability study demonstrated that the pH and the color of the medium progressively deteriorate over time as temperatures increase between 30 °C and 50 °C. Growth promotion of Staphylococcus aureus was favorable with recovery rates between 20 and 40 CFU bottle-1. Discussion: HemoCen Aerobic is functional with a satisfactory analytical performance, which recovery rates are consistent with the values reported in bacteremia of low magnitude. These results provide the basis for planning a shelf stability study under real conditions. Conclusion: A durability period of 2 years was estimated(AU)

Analytical Performance of New ARCHITECT AFP Assay: Comparison with the Current Assay

Alpha-fetoprotein (AFP) is frequently used for hepatocellular carcinoma (HCC) diagnosis and surveillance. Although the current ARCHITECT AFP (List number 7K67) assay range is 0–350 ng/mL, all samples with test results between 200 and 350 ng/mL must be diluted and retested until their levels are <200 ng/mL. A new ARCHITECT AFP (8100/3P36) assay with a dynamic range of up to 2000 ng/mL has been introduced. The aim of this study was to perform a method comparison between the current ARCHITECT AFP assay and the new assay. The precision study showed excellent results for both high and low controls. There was a positive correlation between the two assay systems and clinical samples. The new ARCHITECT AFP assay with a wide assay range demonstrated good analytical performance. Therefore, the current ARCHITECT AFP assay could be replaced by the new assay, which is more convenient and minimizes manual labor.

Especificaciones de calidad en base a error total: ¿Cuál es la mejor elección? / Quality specifications based on total error: What's the best choice? / Especificações de qualidade com base em erro total: Qual é a melhor escolha?

El objetivo del trabajo fue evaluar el desempeño anual de los métodos, en términos de error total (ET), las distintas especificaciones de calidad disponibles y el modelo Seis Sigma para calificar desempeño. Se evaluaron analitos con variabilidad biológica (VB), muy baja, baja, media y alta. Se calculó el ET (ETc) y el sigma (s) mensual a dos niveles de control; el ET permitido (ETp) para cada analito se obtuvo de 8 fuentes (metas biológicas y regulatorias). Se consideró desempeño aceptable cuando ETc

The aim of this work was to evaluate the annual performance of the methods in terms of total error (TE), the different quality specifications available, and the Six Sigma model to qualify performance. Analytes with very low, low, medium and high biological variability (BV) were evaluated. TE (TEc) and sigma (s) were calculated monthly at two levels of control; allowable TE (TEa) for each analyte was obtained from 8 sources (biological and regulatory goals). Acceptable performance was considered when TEc

O objetivo do trabalho foi avaliar o desempenho anual dos métodos em termos de erro total (ET), as diferentes especificações de qualidade disponíveis e o modelo Seis Sigma para qualificar desempenho. Foram avaliados analitos com variabilidade biológica (VB) muito baixa, baixa, média e alta. Calculou-se ET (ETc) e o sigma (s) mensal a dois níveis de controle; o ET permitido (ETp) para cada analito foi obtido de 8 fontes (metas biológicas e regulatórias). Levou-se em consideração o desempenho aceitável quando ETc < ETp e s≥3. Foi observada a estabilidade analítica durante o período de avaliação. Não foram alcançadas as metas biológicas para analitos com VB muito baixa, algo semelhante aconteceu para analitos com VB baixa e média; com VB alta alcançaram todas as especificações. O desempenho s e a regra de controle de Westgard dependeram do ETp escolhido; para magnésio, com CLIA (ETp=25%) se obteve s >10 (World Class) e simples regra (13s), com VB mínima s <3 e multirregra. Conclui-se que a aceitação do desemperno do método e as regras de controle dependeram do ETp escolhido, sem disporem nesse meio de metas mínimas a alcançar. O monitoramento mensal do ETc mostrou a estabilidade analítica com variabilidade típica de cada método.

Evaluation of the analytical performance of AccuTnI+3 assay and establishment of the regional 99th percentile from an apparently healthy Chinese population / 中华检验医学杂志

Objective To validate the analytical performance of a cardiac troponin I(cTnI)assay AccuTnI+3 on chemiluminescnet analyzer DXI800 and Access2;and to establish the 99th percentile of cTnI in an apparently healthy Chinese population.Methods The subjects are composed of 1 369 apparently healthy people and 20 acute myocardial infarction(AMI)patients from Wuhan Asian Heart Hospital and Fuwai Hospital from October 2014 to June 2015.The healthy people include 680 males and 689 females;with 340 subjects aged 18-30,674 subjects aged 31-64, and 355 subjects aged ≥65.The detection limits and imprecision of AccuTnI +3 assays were validated according to CLSI EP 15-A2 and EP17-A2 documents;the same samples were analyzed on DXI800 and Access2 to assess the consistency between the two analyzers using Bland Altman plot and Passing-Bablok regression.The correlation between different sample types (lithium heparin plasma, EDTA plasma & serum)were assessed using linear regression analysis.The lithium heparin plasmasamples from 1 369 apparently healthy people were analyzed to calculate the 99th percentile of cTnI.The cTnI concentrations were compared among age and sex groups.The 99th percentile of cTnI were also calculated for each group.The detection rate of cTnI in apparently healthy people was calculated using SPSS23.0.Results The limit of blank(LoB), limit of detection(LoD), and limit of quantification(LoQ)where CV%=10% were 0.007 ng/ml,0.010 ng/ml and 0.016 ng/ml on DXI800;0.008 ng/ml,0.012 ng/ml and 0.026 ng/ml on Access2,respectively.The cTnI measurements on DXI800 and Access2 were consistent and comparable.The cTnI concentrations of lithium heparin plasma, EDTA plasma and serum samples were linearly correlated pairwise: EDTA plasma measuremen t =0.76 heparin plasma measurement, R2=0.999(n=40, P<0.001); serum measuremen t =1.05 heparin plasma measurement,R2=0.996(n=40,P<0.001); serum measuremen t=1.38 EDTA plasma measurement, R2=0.993(n=40,P<0.001).The 99th percentiles were 0.030 ng/ml and 0.035 ng/ml on DXI800 and Access2,respectively,from 1 369 apparently healthy Chinese people.cTnI is significantly higher in elder group than in younger group.The 99th percentiles in 18-30 years old group,31-64 years old group,and≥65 years old group are:0.011 ng/ml,0.029 ng/ml,and 0.035 ng/ml respectively for DXI800;0.023 ng/ml,0.034 ng/ml, and 0.045 ng/ml respectively for Access2.cTnI is significantly higher in men than in women.The 99th percentiles in men and women are: 0.034 ng/ml and 0.032 ng/ml respectively for DXI800;0.043 ng/ml and 0.031 ng/ml respectively for Access2.cTnI was measurable in 62%and 87%of healthy subjects on DXI800 and Access2 systems,respectively.Conclusions The analytical performance of AccuTnI+3 assay fulfills the need of clinical use and the criteria of high-sensitive cardiac troponin assay.

Analytical performance verification of continuous monitoring assay for detecting plasma GLDH activity / 国际检验医学杂志

Objective To evaluate the analytical performance of glutamate dehydrogenase(GLDH) activity detection kit using continuous monitoring assay.Methods GLDH activity was determined by using continuous monitoring assay on ADVIA 2400 automatic biochemistry analyzer.Performance characteristics,including precision,linearity,interference and accuracy,were evaluated respectively according to EP5-A2,EP 6-A,EP7-A2,EP15-A document issued by Clinical and Laboratory Standards Institute(CLSI).Results The coefficient of variation(CV) of within-run and total precision at high concentration(45.0 U/L) were 3.09% and 3.83% respectively,CV of within-run and total precision at low concentration(21.1 U/L) were 4.88% and 5.74% respectively.The linear range was 2.9-155.4 U/L.The interference bias of 2 g/L hemoglobin,342 μmol/L bilirubin,0.3 g/L vitamin C and 5.6 mmol/L triglyceride were less than 4.82%.For the accuracy based tests,the bias was less than 10.59%.Conclusion The analytical performance of the GLDH detection kit could achieve the manufacturer''s performance indication and meet the clinical needs.

Performance Evaluation of the JEOL BioMajesty JCA-BM6010/C Automated Clinical Chemistry Analyzer

BACKGROUND: JEOL BioMajesty JCA-BM6010/C (JCA-BM6010/C, JEOL Ltd., Japan) is a recently developed ultra-compact automated clinical chemistry analyzer with a throughput of 1,200 tests per hour. Here, we present the first performance evaluation of JCA-BM6010/C. METHODS: We evaluated the precision, linearity, correlation, accuracy, and carryover of 11 analytes (ALP, ALT, AST, calcium, creatinine, GGT, glucose, LDH, total bilirubin, total protein, and uric acid) using the JEOL closed reagent (JEOL Ltd.) according to the guidelines of the Clinical Laboratory Standards Institute. Linearity was further evaluated for ALT, AST, and GGT using open reagents by Sekisui (Japan). The performance of JCA-BM6010/C was compared to that of the Roche-Hitachi Cobas 8000 c702 chemistry autoanalyzer (Cobas 8000, Roche Diagnostics, Switzerland). Its performance using open reagents from Denka Seiken (Japan), Roche, and Sekisui was also evaluated. RESULTS: The total coefficients of variation (CV) for all analytes were 1.0–2.7%. Linearity was observed for all analytes over the entire tested analytical range (R²≥0.99). The results of JCA-BM6010/C strongly correlated (r≥0.988) with those of Cobas 8000 for all evaluated analytes except LDH (r=0.963), as well as for all open reagents. Recovery rates for creatinine, glucose, calcium, and uric acid were 96.6–101.5% and 98.7–109.3% with the JEOL exclusive and open reagents, respectively. Sample carryover was less than 0.34%. CONCLUSIONS: JCA-BM6010/C showed acceptable performance in the precision, linearity, correlation, accuracy, and sample carryover analyses and in the method comparison. Therefore, it could be a useful routine laboratory medical analyzer.

Analytical Performance of Bio-Rad D-100 on a Hemoglobin A1c Assay

BACKGROUND: Hemoglobin A1c (HbA1c) is considered a marker useful for the follow-up and diagnosis of diabetes and implies the importance of reliable assay methods that are traceable to a reference method. We evaluated analytical performance of a new high-performance liquid chromatography system for the HbA1c assay: D-100 from Bio-Rad Laboratories (USA). METHODS: We evaluated precision, linearity, and carry-over of D-100, according to the Clinical and Laboratory Standards Institute's guidelines. Comparative analysis of D-100 with Integra 800 (Roche Diagnostics, Germany) and Capillarys 3 (Sebia, France) was conducted. Additionally, we evaluated the throughput of the three instruments. RESULTS: Precision of low- and high-concentration controls in D-100 showed a CV of less than 1%. The linearity was excellent (R²=0.999) in the range of 3.51-18.7%, and carry-over was not observed. HbA1c results of D-100 (n=144) showed good correlation with those of Integra 800 (r=0.993) and Capillarys 3 (r=0.996). The % bias between D-100 and Integra 800 or Capillarys 3 was within the allowable range at all 3 medical decision levels (5.7%, 6.5%, and 10.0%). Elapsed time in the analysis of the first sample by D-100 was shorter than that of Integra 800 (2.4 vs. 11.1 minutes), but subsequent samples took more time (0.8 vs. 0.3 minutes per sample). CONCLUSIONS: D-100 showed reliable analytical performance with good precision and linearity, minimal carry-over, and acceptable comparative characteristics relative to other instruments. D-100 is expected to be useful for clinical measurements of HbA1c for diabetes diagnosis and theranostics.

Fragment Analysis for Detection of the FLT3-Internal Tandem Duplication: Comparison with Conventional PCR and Sanger Sequencing

BACKGROUND: We evaluated a sensitive and quantitative method utilizing fragment analysis of the fms-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD), simultaneously measuring mutant allele burden and length, and verified the analytical performance. METHODS: The number and allelic burden of FLT3-ITD mutations was determined by fragment analysis. Serial mixtures of mutant and wild-type plasmid DNA were used to calculate the limit of detection of fragment analysis, conventional PCR, and Sanger sequencing. Specificity was evaluated using DNA samples derived from 50 normal donors. Results of fragment analysis were compared to those of conventional PCR, using 481 AML specimens. RESULTS: Defined mixtures were consistently and accurately identified by fragment analysis at a 5% relative concentration of mutant to wild-type, and at 10% and 20% ratios by conventional PCR and direct sequencing, respectively. No false positivity was identified. Among 481 AML specimens, 40.1% (193/481) had FLT3-ITD mutations. The mutant allele burden (1.7-94.1%; median, 28.2%) and repeated length of the mutation (14-153 bp; median, 49 bp) were variable. The concordance rate between fragment analysis and conventional PCR was 97.7% (470/481). Fragment analysis was more sensitive than conventional PCR and detected 11 additional cases: seven had mutations below 10%, three cases represented conventional PCR failure, and one case showed false negativity because of short ITD length (14 bp). CONCLUSIONS: The new fragment analysis method proved to be sensitive and reliable for the detection and monitoring of FLT3-ITD in patients with AML. This could be used to simultaneously assess ITD mutant allele burden and length.

Evaluation of Analytical Performance of the D-100 Hemoglobin Testing System for Hemoglobin A1c Assay

BACKGROUND: The hemoglobin A1c (HbA1c) level is widely used to diagnose and monitor glycaemic control in people with diabetes mellitus, and various methods are used for its determination. The D-100 hemoglobin testing system (Bio-Rad Laboratories, USA) is a fully automated, high-throughput glycohaemoglobin analyzer based on an ion-exchange high-performance liquid chromatographic method. Here, we evaluated the analytical performance of a newly developed HbA1c analyzer. METHODS: Precision, linearity, and comparison to the Variant II Turbo analyzer (Bio-Rad Laboratories, USA) were evaluated according to the Clinical Laboratory Standards Institute guidelines. Carryover, bias from the value assigned by the HbA1c Network Laboratory of Korea Centers for Disease Control and Prevention, and the vulnerability to interference by hemoglobin variants frequently found in Korea were also assessed. Statistical analyses were performed using Excel 2010 (Microsoft Co., USA) and MedCalc ver. 14.12.0 (MedCalc Software bvba, Belgium). RESULTS: The coefficients of variation for repeatability and within-device precision were less than 1.08% in National Glycohaemoglobin Standardization Program (NGSP) unit and less than 1.68% in international system of unit at all three levels. The calibration curve was linear, with R²=0.996 in the range of 4.6% to 15.4% in NGSP unit. The results highly correlated with those produced by Variant II Turbo (r=0.998). The 95% confidence interval for differences from the assigned values was -3.3% to 2.9%. No significant interferences of haemoglobin variants were observed except for Hemoglobin Yamagata. CONCLUSIONS: The D-100 hemoglobin testing system showed excellent precision, linearity, and good correlation with the Variant II Turbo analyzer and agreement with the assigned values. Therefore, its analytical performance is satisfactory for diabetes diagnosis and treatment monitoring.

Performance Evaluation of the Elecsys Neuron-Specific Enolase Assay

BACKGROUND: Neuron-specific enolase (NSE) is an enzyme specifically found in neurons and neuroendocrine tissue. It is a common marker for small cell lung cancer diagnosis and is also useful as a predictor of brain damage. This study evaluates the performance of Elecsys NSE (Roche Diagnostics, Switzerland), an electrochemiluminescent immunoassay. METHODS: The precision, linearity, limit of detection, and reference interval of the Elecsys NSE, as well as the correlation between Elecsys NSE and ELSA-NSE (Cis-Bio International, France) were evaluated in accordance with the Clinical Laboratory Standards Institute (CLSI) guidelines. PreciControl Tumor Marker (Roche Diagnostics), patient sera, and sera from healthy individuals were used for the analysis. RESULTS: The measured coefficient of variation for the assay was below 3%, and it demonstrated linearity from 0.20 to 234.5 ng/mL. The detection limit was 0.032 ng/mL and the reference interval ranged from 0.05 to 16.3 ng/mL. Compared with the ELSA-NSE assay, the correlation coefficient was 0.9128. CONCLUSIONS: The Elecsys assay showed suitable precision, linearity, limit of detection and reference range for clinical laboratory use; however, the correlation coefficient of Elecsys NSE as compared to ELSA-NSE was below 0.975. This result may be associated with the use of different monoclonal antibodies in the two different NSE assays. Elecsys NSE demonstrated a high sensitivity without the use of radioactive reagents; therefore, Elecsys NSE will be quite useful for NSE analysis in the clinical laboratory setting.

Performance Evaluation of the Elecsys Neuron-Specific Enolase Assay

BACKGROUND: Neuron-specific enolase (NSE) is an enzyme specifically found in neurons and neuroendocrine tissue. It is a common marker for small cell lung cancer diagnosis and is also useful as a predictor of brain damage. This study evaluates the performance of Elecsys NSE (Roche Diagnostics, Switzerland), an electrochemiluminescent immunoassay. METHODS: The precision, linearity, limit of detection, and reference interval of the Elecsys NSE, as well as the correlation between Elecsys NSE and ELSA-NSE (Cis-Bio International, France) were evaluated in accordance with the Clinical Laboratory Standards Institute (CLSI) guidelines. PreciControl Tumor Marker (Roche Diagnostics), patient sera, and sera from healthy individuals were used for the analysis. RESULTS: The measured coefficient of variation for the assay was below 3%, and it demonstrated linearity from 0.20 to 234.5 ng/mL. The detection limit was 0.032 ng/mL and the reference interval ranged from 0.05 to 16.3 ng/mL. Compared with the ELSA-NSE assay, the correlation coefficient was 0.9128. CONCLUSIONS: The Elecsys assay showed suitable precision, linearity, limit of detection and reference range for clinical laboratory use; however, the correlation coefficient of Elecsys NSE as compared to ELSA-NSE was below 0.975. This result may be associated with the use of different monoclonal antibodies in the two different NSE assays. Elecsys NSE demonstrated a high sensitivity without the use of radioactive reagents; therefore, Elecsys NSE will be quite useful for NSE analysis in the clinical laboratory setting.

Evaluación del desempeño analítico de tres métodos de cuantificación de hemoglobina A1c / Analytical performance evaluation of three methods for hemoglobin A1c quantification / Avaliação do desempenho analítico do três métodos de quantificação de hemoglobina A1c

El laboratorio debe garantizar la exactitud de los resultados de HbA1c cumpliendo con los requisitos analíticos internacionales de calidad, cada vez más estrictos y asegurar que una variación de HbA1c de 0,5 puntos porcentuales (%-NGSP) o más entre dos controles consecutivos de un paciente diabético se deba a una variación clínica y no a una variación analítica. En este trabajo se evaluó el desempeño analítico de tres métodos comerciales para HbA1c: inmunoturbidimétrico, enzimático y cromatográfico de intercambio catiónico. Para tal fin, se procesaron por cada método distintos controles comerciales de HbA1c, con trazabilidad al método de referencia IFCC, determinándose en cada caso Coeficiente de Variación Total, Bias, Error Total, Valor de Referencia del Cambio y cambio clínico significativo de HbA1c en el punto crítico 7,0%-NGSP. En las condiciones analíticas de este trabajo, solamente el método inmunoturbidimétrico tuvo un desempeño analítico aceptable, permitiendo atribuir un cambio de 0,5%-NGSP a una variación clínica significativa del paciente. Frente a las recomendaciones internacionales sobre el uso de HbA1c en el control y diagnóstico de diabetes, es indiscutible la importancia de elegir un método que satisfaga los requerimientos analíticos mínimos de calidad para asegurar la utilidad clínica del resultado de HbA1c.

The laboratory must guarantee the accuracy of HbA1c results meeting the increasingly strict international analytical quality standards and assuring that an HbA1c variation of 0.5 percentage points (%-NGSP) or more between two consecutive controls of a diabetic patient is due to a clinical variation and not to an analytical variation. In this paper, the analytical performance of three commercial methods for HbA1c: Immunoturbidimetric, Chromatographic and Enzymatic Cation Exchange, were evaluated. For this purpose, commercial controls with assigned values traceable to the IFCC reference method for HbA1c were processed. For each methodology, total Coefficient of Variation (CV%), Bias%, Total Error (TE%), Change Reference Value and Clinically Significant Change (CSC) at the critical point of HbA1c 7.0%-NGSP were determined. Within the analytical conditions of this study, only the immunoturbidimetric method had an acceptable analytical performance, allowing attribute a change in 0.5%-NGSP to a significant clinical variation. Faced with international recommendations on the use of HbA1c on control and diagnosis of diabetes, the importance of choosing a method that meets the minimum analytical quality requirements to ensure the clinical utility of HbA1c result is undeniable.

O laboratório deve garantir a precisão dos resultados da HbA1c cumprindo com os requisitos analíticos internacionais de qualidade cada vez mais exigentes e garantir que uma variação de HbA1c de 0,5 pontos percentuais (% - NGSP) ou mais entre duas verificações consecutivas de um doente diabético seja devido a uma variação clínica e não a uma variação analítica. Neste trabalho foi avaliado o desempenho analítico de três métodos comerciais para HbA1c: imunoturbidimétrico, enzimático e cromatográfico de intercâmbio catiônico. Para esse fim, foram processados diversos controles comerciais de HbA1c por cada método, com rastreabilidade ao método de referência IFCC, determinando em cada caso Quociente de Variação Total, Bias, Erro Total, Valor de Referência da Alteração e Alteração Clinicamente Significativa de HbA1c no ponto crítico 7,0%-NGSP. Nas condições de análise deste estudo, apenas o método imunoturbidimétrico teve um desempenho analítico aceitável, permitindo atribuir uma alteração de 0,5%-NGSP a uma variação clínica significativa do paciente. Perante as recomendações internacionais sobre o uso da HbA1c no controle e diagnóstico da diabetes, é inegável a importância de escolher um método que atenda os requisitos analíticos mínimos de qualidade de análise para garantir a utilidade clínica do resultado HbA1c.

Avaliação do desempenho analítico do analisador hematológico Sysmex® XE-2100D / Performance evaluation of the Sysmex XE-2100D automated hematology analyzer

Introduction: The Sysmex® XE-2100D is a multiparameter hematology analyzer designed for hematology testing in samples with ethylenediamine tetraacetic acid (EDTA). Objectives: Considering the importance of this hematology analyzer for clinical and laboratory practice, the objective of this study was to evaluate its analytical performance, comparing the obtained results with quality specifications described in literature. Material and method: In the evaluation of analytical performance, according to recommendations of the document H26-A2 of the Clinical and Laboratory Standards Institute (CLSI), intra-run imprecision, inter-run imprecision, linearity, carryover, autosampler evaluation, clinical sensitivity of the atypical lymphocytes flag (n = 400 samples) were included, as well as the comparison between automated and manual leukocyte differential count (n = 400 samples), based on an adaptation of the document H20-A2 of CLSI. Results: Repeatability, reproducibility, linearity and carryover were satisfactory according to the manufacturer's specifications. The clinical sensitivity of the atypical lymphocytes flag showed efficiency, sensitivity and specificity of 92.5%, 65.2% and 94.1% respectively. The correlation coefficients between the automated and manual differential counts of neutrophils, lymphocytes, monocytes, eosinophils and basophils were 0.991, 0.99, 0.872, 0.974 and 0.557, respectively. Conclusions: The results were in accordance with quality specifications described in literature, indicating reliability in Sysmex® XE-2100D. This fact ensures certainty to both laboratory professionals and medical staff. We conclude that the Sysmex® XE-2100D showed excellent analytical performance, and is useful to provide reliable hematology data...

Introdução: O Sysmex® XE-2100D é um analisador hematológico multiparamétrico destinado à realização de testes hematológicos em sangue anticoagulado com ácido etilenodiamino tetra-acético (EDTA). Objetivos: Considerando a sua importância na prática clínica e laboratorial, o objetivo deste estudo foi avaliar seu desempenho analítico, comparando os resultados obtidos com especificações de qualidade descritas na literatura. Material e método: Na avaliação de desempenho analítico, conforme recomendações do documento H26-A2 do Clinical and Laboratory Standards Institute (CLSI), foram incluídos ensaios de verificação da imprecisão intraensaio ou repetitividade, imprecisão entre ensaios ou reprodutibilidade, linearidade, carryover (arraste), avaliação do mecanismo homogeneizador de amostras, sensibilidade clínica do alerta morfológico (flag) de linfócitos atípicos (n = 400 amostras) e a comparação entre a contagem diferencial de leucócitos automatizada e a manual (n = 400 amostras), baseada em uma adaptação do documento H20-A2 do CLSI. Resultados: Os ensaios de verificação da repetitividade, reprodutibilidade, linearidade, carryover (arraste) foram satisfatórios conforme especificações do fabricante. O ensaio de sensibilidade clínica do alerta morfológico (flag) de linfócitos atípicos mostrou eficiência, sensibilidade e especificidade de 92,5%; 65,2% e 94,1% respectivamente. Os coeficientes de correlação entre as contagens diferenciais automatizadas e manuais de neutrófilos, linfócitos, monócitos, eosinófilos e basófilos foram de 0,991; 0,99; 0,872; 0,974 e 0,557 respectivamente...

Development of a time-resolved fluorescence immunoassay for rapid determinat-ion of levels of cardiac troponin Ⅰantigen in human serum / 中国免疫学杂志

To establish a method to detect cardiac troponin I by using time-resolved fluoroimmunoassay ( TRFIA) and apply to the clinic.Methods:The assay were measured by TRIFA and double antibody sandwich method .Standard protocols were evaluated with the standard curve , the limit of detection , stability, precision and cross reaction .Healthy reference populations and clinical serum specimens were measured to established the reference interval and evaluated the perspective of the clinical application . Results:The standard curve was Y=7485 .878+1400.924 X with a correlation coefficient of 0.999.The limit of detection was 0.052 ng/ml.The intra-and inter-assay coefficients of variation ( CV) were all 0.05 ).There was significant difference in statistics compared before and after treatment with AMI ( P<0.001 ) .Conclusion: The TRFIA method for detecting cTnI achieves clinical application standards and may be used for the diagnosis and serosurveillance of acute myocardial infarction patients.