scholarly journals Distribution characteristics of SARS-CoV-2 IgM and IgG in false-positive results detected by Chemiluminescent immunoassay

2021 ◽  
Author(s):  
Yan Lei ◽  
Xiaolan Lu ◽  
Daiyong Mou ◽  
Qin Du ◽  
Guo Bin ◽  
...  
Keyword(s):  
False Positive ◽  
Dynamic Monitoring ◽  
Antibody Detection ◽  
Distribution Characteristics ◽  
Igg Antibodies ◽  
Dynamic Changes ◽  
Positive Proportion ◽  
Chemiluminescent Immunoassay ◽  
False Positive Probability ◽  
Positive Results

Abstract There have been several false-positive results in the antibody detection of the COVID-19. This study aims to analyze the distribution characteristics of SARS-CoV-2 IgM and IgG in false-positive results detected using chemiluminescent immunoassay. The characteristics of the false-positive results in SARS-CoV-2 IgM and IgG testing were retrospectively analyzed. The dynamic changes in the results of SARS-CoV-2 IgM and IgG antibodies were observed. The false-positive proportion of the single SARS-CoV-2 IgM positive results was 95.88%, which was significantly higher than those of the single SARS-CoV-2 IgG positive results (67.50%) (P < 0.001) and SARS-CoV-2 IgM & IgG positive results (29.55%) (P < 0.001). The S/CO of the SARS-CoV-2 IgM and IgG in false-positive results ranged from 1.0 to 50.0. The false-positive probability of SARS-CoV-2 IgM in the S/CO range (1.0 ~ 3.0) was 91.73% (77/84), and the probability of false-positive of SARS-CoV-2 IgG in the S/CO range (1.0 ~ 2.0) was 85.71% (24/28). Dynamic monitoring showed that the S/CO values of IgM in false-positive results decreased or remained unchanged, whereas the S/CO values of IgG in false-positive results only decreased. The possibility of false-positive of the single SARS-CoV-2 IgM positive and single SARS-CoV-2 IgG positive results was high. As the value of S/CO decreased, the probability of false-positive consequently increased, especially among the single SARS-CoV-2 IgM positive results.

Use of chicken antibodies in enzyme immunoassays to avoid interference by rheumatoid factors

1991 ◽  
Vol 37 (3) ◽  
pp. 411-414 ◽  
Author(s):  
Anders Larsson ◽  
Alex Karlsson-Parra ◽  
J Sjöquist
Keyword(s):  
Monoclonal Antibodies ◽  
False Positive ◽  
Mammalian Species ◽  
Sandwich Elisa ◽  
Rheumatoid Factors ◽  
Igg Antibodies ◽  
False Positive Reaction ◽  
Avian Origin ◽  
Capture Antibody ◽  
Positive Results

Abstract Rheumatoid factor (RF) is a major source of interference in many immunoassays. Most immunoassays use mammalian polyclonal or monoclonal antibodies, and RF can react with IgG from mammalian species, thus causing false-positive results. In this work we have studied RF interference in a sandwich ELISA, where RF in the sample may react with both the capture antibody and the detection antibody to give a false-positive reaction. We show that rheumatoid factors do not react with chicken IgY; if the capture antibody or detection antibody (or both) is of avian origin, the interference of RF or other anti-IgG antibodies in sandwich ELISA can be avoided.

scholarly journals A Case of Malaria Patient with SARS-CoV-2 Antibody False-Positive

2021 ◽  
Author(s):  
hong zhou
Keyword(s):  
Nucleic Acid ◽  
False Positive ◽  
Malaria Patient ◽  
Antibody Detection ◽  
Nucleic Acid Detection ◽  
Malaria Rapid Diagnostic Test ◽  
Igg Antibody ◽  
Case Presentation ◽  
Igm Antibody ◽  
Positive Results

Abstract Background: The SARS-CoV-2 antibody detection are used to diagnose or exclude suspected COVID-19 patients as a supplement to nucleic acid detection. False-positive results of SARS-CoV-2 antibody have been reported but rarely associated with malaria. A case of malaria patient with SARS-CoV-2 antibody false-positive is described.Case presentation: A 24 year-old male returned from Côte d’Ivoire was diagnosed Plasmodium falciparum by Malaria rapid diagnostic test. The patient had suspicious exposure to COVID-19. His SARS-CoV-2 IgM antibody was positive one day before admission and turned negative on the 18th day of admission, while the IgG antibody and nasopharyngeal swabs SARS-Cov-2 nucleic acid had been negative. Conclusion: Malaria might cause false positive for SARS-CoV-2 IgM antibody. A careful interpretation of the SARS-CoV-2 antibody result is useful to avoid wasting medical resources especially malaria-endemic areas.

scholarly journals Chemiluminescence Assay Improves Specificity of Hepatitis C Antibody Detection

2003 ◽  
Vol 49 (6) ◽  
pp. 940-944 ◽  
Author(s):  
D Robert Dufour ◽  
Mageli Talastas ◽  
Maria D A Fernandez ◽  
Barbara Harris
Keyword(s):  
Hepatitis C ◽  
False Positive ◽  
Screening Program ◽  
Antibody Detection ◽  
Hcv Rna ◽  
Chemiluminescence Assay ◽  
Positive Rate ◽  
Recombinant Immunoblot Assay ◽  
Hcv Screening ◽  
Positive Results

Abstract Background: Antibodies to hepatitis C virus (anti-HCV) have typically been detected by enzyme immunoassay (EIA). A chemiluminescence assay (CA) for anti-HCV is now commercially available. Methods: We compared the positive rate for a CA in a HCV screening program for veterans with historical rates obtained with EIA. We also compared results in 2824 samples tested by both methods and assessed the significance of low signal-to-cutoff (S/C) ratios. Results: The frequency of CA-positive results was significantly lower than with EIA (12.6% vs 16.0%; P &lt;0.0001). The frequency of low S/C ratios was also significantly lower with CA (11.5% vs 20.0%; P &lt;0.0001). Among low-positive values, samples positive by CA were significantly less likely to be recombinant immunoblot assay (RIBA)-negative (64% vs 84%; P &lt;0.0005). In parallel testing, results for 111 samples (3.9%) were discrepant between the two assays; all but 6 had low S/C ratios, and confirmatory testing was performed on all but 8 samples. Of 56 EIA-positive, CA-negative samples tested by RIBA, only 1 was positive. Of 24 CA-positive, EIA-negative samples, 62% were RIBA-negative. Using a negative RIBA result as an indication of false-positive anti-HCV results, the positive predictive value of EIA was 93% compared with 98% with CA. HCV RNA was positive in 90% of samples high-positive by both CA and EIA. Only 2 of 30 (7%) low-positive CA samples were RNA-positive. Conclusions: CA produces fewer false-positive and fewer low-positive results that require confirmatory RIBA testing. The S/C ratio remains useful for characterizing positive results.

scholarly journals Dengue antibodies can cross-react with SARS-CoV-2 and vice versa-Antibody detection kits can give false-positive results for both viruses in regions where both COVID-19 and Dengue co-exist

2020 ◽  
Author(s):  
Himadri Nath ◽  
Abinash Mallick ◽  
Subrata Roy ◽  
Soumi Sukla ◽  
Keya Basu ◽  
...  
Keyword(s):  
False Positive ◽  
Virus Antigen ◽  
Definitive Diagnosis ◽  
Antibody Detection ◽  
Serum Samples ◽  
Positive Serum ◽  
Antigen Tests ◽  
Positive Results

AbstractFive of thirteen Dengue antibody-positive serum samples, dated 2017 (pre-dating the COVID-19 outbreak) produced false-positive results in SARS-CoV-2 IgG/IgM rapid strip tests. Our results emphasize the importance of NAT and/or virus antigen tests to complement sero-surveillance for definitive diagnosis of COVID-19/Dengue in regions where both viruses are co-endemic.

scholarly journals Enzyme-Linked Immunosorbent Assay, Immunofluorescent Assay X and Recombinant Immunoblotting in the Serodiagnosis of Early Lyme Borreliosis

2003 ◽  
Vol 16 (3) ◽  
pp. 261-268 ◽  
Author(s):  
I. Christova
Keyword(s):  
Lyme Borreliosis ◽  
Antibody Detection ◽  
Enzyme Linked Immunosorbent Assay ◽  
Control Group ◽  
Igg Antibodies ◽  
Serum Samples ◽  
Specific Antibodies ◽  
Immunofluorescent Assay ◽  
Igm Elisa ◽  
Positive Results

Serum samples from Bulgarian patients with physician-diagnosed erythema migrans (EM) (n=105) were examined using Borrelia burgdorferi ELISA (Boehring, Germany) after previous absorption with Treponema phagedenis. For IgM antibody detection sera were additionally pretreated with anti-IgG serum (RF absorbent). Serum samples of 93 % of persons from healthy control group were IgM negative and all were IgG negative. Out of 105 patients with EM, 49 % were IgM positive and 14 % were borderline. IgG ELISA showed positive results for 17 % and borderline for 6 % of the patients. Positive and borderline serum samples were examined further by immunofluorescent assay (IFA) and immunoblot test with recombinant B. burgdorferi proteins from strain PKo ( B. afzelii) - p100, flagellin, OspA and OspC, and internal flagellin fragments from strains PKo and PBi ( β. garinii) [B. Wilske, V. Fingerle, P. Herzer et al. 1993. Med. Microbiol. Immunol. 182:255]. IFA detected IgM antibodies against B. burgdorferi in 47 % of the positive and in none of the borderline by IgM ELISA serum samples as well as IgG antibodies in 83 % of the positive and in 50% of the borderline by IgG ELISA samples. Presence of specific antibodies was confirmed by immunoblot in 71 % of the IgM ELISA postive and in 67 % of the IgG ELISA positive sera. In addition, anti-β. burgdorferi antibodies were detected in 60 % of the borderline by IgM ELISA serum samples. IgM serum reactivity was directed mainly against OspC antigen and flagellin and IgG antibodies were directed mainly against flagellin and p100. These findings clearly showed advantages of the ELISA test based on previous pretreatment of sera and capable to detect specific antibodies in more than half of patients with early Lyme borreliosis despite the well-known delayed immune response. IFA was less sensitive than ELISA in detection of anti- B. burgdorferi antibodies. An additional examination of ELISA borderline sera by immunoblot revealed more positive results. Serum reactivity to a single OspC antigen seems to be a sufficient criterion for positive IgM immunoblot.

scholarly journals Preregistration is important, but not enough: Many statistical analyses can inflate the risk of false-positives

2021 ◽  
Author(s):  
Jacob Dalgaard Christensen ◽  
Jacob Lund Orquin ◽  
Sonja Perkovic ◽  
Carl Johan Lagerkvist
Keyword(s):  
False Positive ◽  
False Positives ◽  
Case Scenario ◽  
Worst Case ◽  
P Values ◽  
Model Sets ◽  
Independent Variable ◽  
Main Effects ◽  
False Positive Probability ◽  
Positive Results

Even with a small number of variables researchers can test many possible models of their data thus increasing the risk of false-positive results. Using combinatorics, we show that one key independent variable and three covariates can generate 95 possible models, while six covariates can generate over 2.3 million models. Such large model sets nearly guarantee false-positive results. Using simulation, we show that preregistering a single analysis with a key independent variable heavily reduces the risk of false-positives. However, even so, many models produce false-positive results with a much higher probability than the expected 5%. The worst-case scenario are models with interactions between binary dummy coded variables and omitted main effects. Such models can generate false-positive results up to 34.5% of the time. While preregistration is a crucial step towards reducing false-positive results, researchers need to carefully consider what analyses they plan and we provide recommendations for what analyses to avoid. Our findings also suggest that interpreting p-values in exploratory analyses might be meaningless considering the high false-positive probability.

Critical Evaluation of Impedance Phlebography for the Diagnosis of Deep Vein Thrombosis

1974 ◽  
Vol 31 (02) ◽  
pp. 273-278
Author(s):  
Kenneth K Wu ◽  
John C Hoak ◽  
Robert W Barnes ◽  
Stuart L Frankel
Keyword(s):  
Deep Vein Thrombosis ◽  
False Positive ◽  
False Negative ◽  
Critical Evaluation ◽  
Original Method ◽  
Vein Thrombosis ◽  
Negative Results ◽  
False Negative Results ◽  
Deep Vein ◽  
Positive Results

SummaryIn order to evaluate its daily variability and reliability, impedance phlebography was performed daily or on alternate days on 61 patients with deep vein thrombosis, of whom 47 also had 125I-fibrinogen uptake tests and 22 had radiographic venography. The results showed that impedance phlebography was highly variable and poorly reliable. False positive results were noted in 8 limbs (18%) and false negative results in 3 limbs (7%). Despite its being simple, rapid and noninvasive, its clinical usefulness is doubtful when performed according to the original method.

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