Comparative performance of four nucleic acid amplification tests for SARS-CoV-2 virus

Coronavirus disease 2019 (COVID-19) can be screened and diagnosed through the detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by real-time reverse transcription polymerase chain reaction. SARS-CoV-2 nucleic acid amplification tests (NAATs) have been rapidly developed and quickly applied to clinical testing during the pandemic. However, studies evaluating the performance of these NAAT assays are limited. We evaluated the performance of four NAATs, which were marked by the Conformite Europeenne and widely used in China during the pandemic. Results showed that the analytical sensitivity of the four assays was significantly lower than that claimed by the NAAT manufacturers. The limit of detection (LOD) of Daan, Sansure, and Hybribio NAATs was 3000 copies/mL, whereas the LOD of Bioperfectus NAATs was 4000 copies/mL. The results of the consistency test using 46 samples showed that Daan, Sansure, and Hybribio NAATs could detect the samples with a specificity of 100% (30/30) and a sensitivity of 100% (16 /16), whereas Bioperfectus NAAT detected the samples with a specificity of 100% (30/30) and a sensitivity 81.25% (13/16). The sensitivity of Bioperfectus NAAT was lower than that of the three other NAATs; this finding was consistent with the result that Bioperfectus NAAT had a higher LOD than the three other kinds of NAATs. The four above mentioned reagents presented high specificity; however, for the detection of the samples with low virus concentration, Bioperfectus reagent had the risk of missing detection. Therefore, the LOD should be considered in the selection of SARS-CoV-2 NAATs.

Expression characteristics of differentiation antigens on granulocytes in patients with megaloblastic anemia / 中国实验血液学杂志

This study was aimed to explore the change characteristics of cell differentiation antigen (CD) on bone marrow (BM) granulocytes in patients,with megaloblastic anemia (MA). In combination with BM cell morphology, hemogram, level of blood serum folic acid, level of Vit B(12), cell genetics and biological examination data, the BM granulocytes differentiation antigens in 13 patients with MA were detected by flow cyto metry and analyzed retrospectively, in order to summarize the variation characteristics of CD13, CD33 and CD15 expressed on myeloid cells in patient with MA, including forward scatter light (FSC) and side scatter light (SSC) signal intensity, then these findings were compared with that in normal healthy persons. The results showed that the expression rates of CD13, CD15 and CD33 on granulocytic in patients with MA and normal healthy persons were (44.53 ± 16)%, (96.16 ± 2.67)%, (80.81 ± 14.71)% and (62.33 ± 11.02)%, (99.53 ± 0.46)%, (70.00 ± 7.81)% respectively, in which the expression rate of CD13 and CD15 in patients with MA decreased (P < 0.01), while the expression rate of CD33 increased (P < 0.01). The mean fluorescence intensity (MFI) of CD13, CD15, CD33, SSC and FSC in MA patients and normal healthy persons were 3.39 ± 1.41, 14.29 ± 6.59, 1.95 ± 0.94, 478.78 ± 70.43, 633.46 ± 75.53 and 5.12 ± 1.15, 20.67 ± 5.13, 1.04 ± 0.17, 332.00 ± 38.16, 537.00 ± 16.70 respectively, in which the MFI of CD13 and CD15 on granulocytes in MA patients decreased (P < 0.01),while the MFI of FSC,SSC and CD33 increased (P < 0.01 and P < 0.05). It is concluded that not only the morphology of BM granulocytes in patents with MA shows dysmaturity, but the expressing feature of differentiation antigens on BM granulocytes in MA patients also displays dysmaturity.These findings will contribute to the clinical diagnosis of MA patients.

Assessment of the performance of an automated analysis system in detecting C3 and C4 / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the performance of BNII auto-analyzer system in detecting C3 and C4.</p><p><b>METHODS</b>CLSI protocols (EP15-A, EP6-A, EP9-A2) and other relevant literatures were use to or evaluate the precision, accuracy, linearity of C3 and C4 detection by the auto-analyzer system, and the results were compared with the recognized standards.</p><p><b>RESULTS</b>The relative bias of C3 and C4 was less than one third of the CLIA'88 standard and the precision met the clinical requirement. The results tested by DADE BNII system were not compatible with those by Roche Modular System. C3 showed good linearity in the tests (R2>0.975, P<0.05) with a linearity range of 0.18-5.1 g/L. The linearity of C4 was not available because of lack of high-level samples.</p><p><b>CONCLUSION</b>The performances of DADE BNII System basically meet the recognized standards in clinical detection of C3 and C4, but the method comparison needs further validation.</p>

Method performance verification of the clinical chemiluminescence immunoassay / 中华检验医学杂志

Objective To establish a method performance verification project and experimental method for the clinical chemiluminescence immunoassay.Methods Referring to CLSI evaluation protocols and pertinent literature,and by combining our actual works,we designed a verification procedure and experimental method.By Using these above,the precision,accuracy,analytical sensitivity,analytical measurement range,clinical reportable range and biotic interval of AFP on the Bayer Centaur 240 chemiluminescence immunoassay system were verificated.Results would be compared with the declaration of the manufacturer or desirable specifications derived from biologic variation.Results The results showed that the between-day inaccuracy on AFP levels at 77.4 ng/ml and 168.0 ng/ml was 5.70% and 4.84% respectively,these were consistent with manufacturer's inaccuracy claimed.The relative bias between the results measured for calibrator at four levels and target value was less 5.0%,and the relative bias between the results measured for EQA control sample at five levels and target value was-3.4% to 11.9%.Lower limit of detection was 1.04 ng/ml,lower slightly manufacturer's analytical sensitivity claimed.Biologic limit of detection was 2.65 ng/ml-3.53 ng/ml,functional sensitivity was 3.53 ng/ml.Analytical measurement range was 3.53-912.00 ng/ml,within manufacturer's liner range claimed.Clinical reportable range was 3.53-182 400.00 ng/ml.Reference interval was 0.6-7.7 ng/ml,within manufacturer' s claimed.Conclusions The main performances of the detection system are accorded with the declaration of the manufacturer.The performance verification procedure and experimental method of our research ars simple and practical,which has important significations for building medical laboratory and laboratory accreditation, improving quality of the chemiluminescence immunoassay.

Using westgard's method evaluation decision chart for judging method performance of routine biochemistry items on Roche Modular PPI testing system / 中华检验医学杂志

Objective To judge method performance of routine biochemistry parameters on Roche Modular PPI testing system by using westgard's method evaluation decision chart.Methods We assessed imprecision(CV)from internal quality control and inaccuracy(bias)from external quality control evaluation.Combined estimates of imprecision and inaccuracy by plotting imprecision as the x-coordinate and inaccuracy as the y-coordinate to locate an expected operating point of every item on the chart.By comparing this operating point with allowable total errors(TEa),we can decide whether the performance is acceptable or not.Results In the 27 different parameters tested,imprecision and bias of calcium were 0.08 mmol/L and 0.06 mmol/L respectively,its performance was marginal.The imprecision of creatinine,urea,glucose, sodium,chloride and phosphorus were 3.20%,2.13%,1.52%,0.89 mmol/L,1.10% and 1.55%,the bias were 4.79%,0.96%,4.63%,0.80 mmol/L,1.74% and 4.13% respectively,their performance was good.M1 other 20 items were of excellence performance.Conclusions Routine biochemistry parameters on Roche Modular PPI testing system possessed good precision and accuracy,and their performance were acceptable.To judge method performance of biochemistry testing system by using westgard' s method evaluation decision chart was easy to do and suited for clinical laboratory.