scholarly journals Occurrence of false positivity in a fourth generation (Ag/Ab) HIV screening assay: horns of a dilemma

2018 ◽  
Vol 6 (7) ◽  
pp. 2423
Author(s):  
Partha Roy ◽  
Ruchi Kapoor ◽  
Priya Rawat ◽  
Monika Aggarwal ◽  
Ravi Gaur ◽  
...  
Keyword(s):  
False Positive ◽  
High Sensitivity ◽  
False Positives ◽  
Fourth Generation ◽  
Hiv Screening ◽  
Grey Zone ◽  
Screening Assay ◽  
Reactive Strategy ◽  
Test Algorithm ◽  
Positive Results

Background: Universal screening for HIV with Ag/Ab combo assays has reduced the window period significantly due to its high sensitivity. However, occurrence of false positives is common and in a country like India, it may lead to social distress and loss of livelihood. We wanted to ascertain the occurrence of false positives in our laboratory.Methods: There were 21817 samples analysed retrospectively from Jan 2015 to Jul 2017 (31 months). Architect HIV Ag/Ab Combo (Abbott Laboratories, Abbott Park, IL) was used as the first test. Repeatedly reactive samples with a signal to cutoff (S/CO) ratio greater than or equal to 1.00 was considered reactive. Strategy III (3 test algorithm) of NACO guidelines was followed uniformly.Results: In this study, 147 samples tested reactive (0.67%) and 40 samples tested false positive (repeatedly reactive; 0.18%). 6 samples were indeterminate (0.027%). Overall, the sensitivity of the Architect HIV Ag/Ab Combo was 100%, the specificity varied between 99.74% and 99.91%. The PPV from June 2016 to July 2017 was 68.63% (32 false positives). The S/CO values of 72.8% (117/147) reactive samples ranged between 201- 800, whereas 72% (29/40) of false positive samples, the S/CO values ranged between 1.0-2.0. The specificity of the test improved to 99.98% when S/CO value was adjusted at 2 and 100% when adjusted at 5. Similarly, the PPV too improved to 93.04% and 98.66% at S/CO values of 2 and 5 respectively.Conclusions: Further studies are needed to ascertain the optimal or ‘grey-zone’ S/CO values for India to minimise the false positive results and avoid further supplemental tests routinely.

scholarly journals A method to alleviate false-positive results of the Elecsys HIV combi PT assay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaolan Lu ◽  
Minghong Zhang ◽  
Wen Liu ◽  
Nan Sheng ◽  
Qin Du ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Retrospective Analysis ◽  
False Positive ◽  
False Positive Rate ◽  
Hiv Screening ◽  
Screening Assay ◽  
Positive Serum ◽  
Positive Rate ◽  
The Difference ◽  
Positive Results

AbstractTo explore the effects of urea dissociation on reducing false-positive results of  the Elecsys HIV combi PT assay. A retrospective analysis was used to evaluate the false-positive rate of the Elecsys HIV combi PT assay. Six false-positive sera, six positive sera and six sera from patients with early HIV infection were collected. Dissociation was performed using 1 mol/L, 2 mol/L, 4 mol/L, 6 mol/L, or 8 mol/L urea, and HIV screening assay were then detected to select the appropriate concentration of urea dissociation. Next, 55 false-positive sera and 15 sera from early HIV infection were used to verify the best concentration of urea to achieve dissociation. Retrospective analysis showed that the COI of the Elecsys HIV combi PT assay in false-positive sera ranged from 1.0 to 200.0, and approximately 97.01%(227/234) of false-positive sera were in the range of 1.0–15.0. The avidity index (AI) in positive and false-positive sera decreased as the urea dissociation concentration increased. When the dissociation concentration was 6 mol/L, the AI of false-positive serum was between 0.0234 and 0.2567, and the AI of early HIV infection sera was between 0.4325 and 0.5017. The difference in AI between false-positive and positive samples was significant. When negativity was defined as an AI of less than 0.3970, the sensitivity and specificity were 100.0% and 100.0%, respectively. Urea-mediated dissociation could significantly reduce the false-positive rate of the Elecsys HIV combi PT assay with a low COI. Our findings provided a reference for distinguishing positive and false-positive of the Elecsys HIV combi PT assay.

scholarly journals False-positive fourth-generation HIV test associated with autoimmune hemolytic anemia. Case report

Case reports ◽  
2019 ◽  
Vol 5 (2) ◽  
pp. 132-138
Author(s):  
Santiago Sánchez-Pardo ◽  
Jaime Andrés Osorio-Ramírez ◽  
Isabela Choi-Park ◽  
Daniel Felipe Rojas-Holguín ◽  
Adrián Bolívar-Mejía
Keyword(s):  
Hiv Infection ◽  
Hemolytic Anemia ◽  
Lupus Erythematosus ◽  
Autoimmune Hemolytic Anemia ◽  
False Positive ◽  
Screening Tests ◽  
Fourth Generation ◽  
Hiv Screening ◽  
Hiv Test ◽  
Positive Results

Introduction: The fourth-generation ELISA human immunodeficiency virus (HIV) screening test has a high sensitivity and specificity >99% to detect both antigens and antibodies. Estimates are that only 0.5% yield false positive results.Case description: 61-year-old female patient with a clinical picture consisting of malaise, unquantified fever, asthenia and adynamia. Laboratory tests revealed anemia, so a Coombs test was performed, obtaining a positive result along with other findings of mixed autoimmune hemolytic anemia. Two fourth-generation ELISA HIV screening tests were performed obtaining positive results. Given the national recommendations on the diagnosis of HIV infection, a viral load was performed, which turned out to be negative, so the result was considered a false positive.Discussion: Clinical and biological factors are related to false positive results. There are descriptions about autoimmunity phenomena, such as systemic lupus erythematosus or autoimmune hemolytic anemia, with few cases in older adults.Conclusions: Rapid tests have changed the diagnosis of HIV infection worldwide; however, like any other diagnostic test, they may yield false positive results with differential diagnoses, including autoimmune hemolytic anemia.

scholarly journals Human Immunodeficiency Virus Diagnostic Testing: 30 Years of Evolution

2016 ◽  
Vol 23 (4) ◽  
pp. 249-253 ◽  
Author(s):  
Thomas S. Alexander
Keyword(s):  
False Positive ◽  
Diagnostic Testing ◽  
Antibody Test ◽  
Fourth Generation ◽  
Igg Antibody ◽  
Screening Assay ◽  
Aids Epidemic ◽  
Fifth Generation ◽  
Hiv Test ◽  
Positive Results

ABSTRACTA concern during the early AIDS epidemic was the lack of a test to identify individuals who carried the virus. The first HIV antibody test, developed in 1985, was designed to screen blood products, not to diagnose AIDS. The first-generation assays detected IgG antibody and became positive 6 to 12 weeks postinfection. False-positive results occurred; thus, a two-test algorithm was developed using a Western blot or immunofluorescence test as a confirmatory procedure. The second-generation HIV test added recombinant antigens, and the third-generation HIV tests included IgM detection, reducing the test-negative window to approximately 3 weeks postinfection. Fourth- and fifth-generation HIV assays added p24 antigen detection to the screening assay, reducing the test-negative window to 11 to 14 days. A new algorithm addressed the fourth-generation assay's ability to detect both antibody and antigen and yet not differentiate between them. The fifth-generation HIV assay provides separate antigen and antibody results and will require yet another algorithm. HIV infection may now be detected approximately 2 weeks postexposure, with a reduced number of false-positive results.

scholarly journals Automated detection of cribriform growth patterns in prostate histology images

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Pierre Ambrosini ◽  
Eva Hollemans ◽  
Charlotte F. Kweldam ◽  
Geert J. L. H. van Leenders ◽  
Sjoerd Stallinga ◽  
...  
Keyword(s):  
Deep Learning ◽  
False Positive ◽  
Clinical Decision Making ◽  
False Negative ◽  
Area Under The Curve ◽  
High Sensitivity ◽  
False Positives ◽  
Growth Patterns ◽  
Learning Method ◽  
Method Performance

Abstract Cribriform growth patterns in prostate carcinoma are associated with poor prognosis. We aimed to introduce a deep learning method to detect such patterns automatically. To do so, convolutional neural network was trained to detect cribriform growth patterns on 128 prostate needle biopsies. Ensemble learning taking into account other tumor growth patterns during training was used to cope with heterogeneous and limited tumor tissue occurrences. ROC and FROC analyses were applied to assess network performance regarding detection of biopsies harboring cribriform growth pattern. The ROC analysis yielded a mean area under the curve up to 0.81. FROC analysis demonstrated a sensitivity of 0.9 for regions larger than $${0.0150}\,\hbox {mm}^{2}$$ 0.0150 mm 2 with on average 7.5 false positives. To benchmark method performance for intra-observer annotation variability, false positive and negative detections were re-evaluated by the pathologists. Pathologists considered 9% of the false positive regions as cribriform, and 11% as possibly cribriform; 44% of the false negative regions were not annotated as cribriform. As a final experiment, the network was also applied on a dataset of 60 biopsy regions annotated by 23 pathologists. With the cut-off reaching highest sensitivity, all images annotated as cribriform by at least 7/23 of the pathologists, were all detected as cribriform by the network and 9/60 of the images were detected as cribriform whereas no pathologist labelled them as such. In conclusion, the proposed deep learning method has high sensitivity for detecting cribriform growth patterns at the expense of a limited number of false positives. It can detect cribriform regions that are labelled as such by at least a minority of pathologists. Therefore, it could assist clinical decision making by suggesting suspicious regions.

scholarly journals Benzene Derivatives from Ink Lead to False Positive Results in Neonatal Hyperphenylalaninemia Screening with Ninhydrin Fluorometric Method

2020 ◽  
Vol 6 (1) ◽  
pp. 14
Author(s):  
Shuren Feng ◽  
Joanne Mei ◽  
Lu Yang ◽  
Ping Luo ◽  
Xiaonan Wang ◽  
...  
Keyword(s):  
False Positive ◽  
High Performance ◽  
Low Cost ◽  
High Sensitivity ◽  
Benzene Derivatives ◽  
Negative Results ◽  
Specimen Collection ◽  
Blood Specimens ◽  
Ethanol Extracts ◽  
Positive Results

Ninhydrin-based fluorometric quantification of phenylalanine is one of the most widely used methods for hyperphenylalaninemia (HPA) screening in neonates due to its high sensitivity, high accuracy, and low cost. Here we report an increase of false positive cases in neonatal HPA screening with this method, caused by contamination of blood specimen collection devices during the printing process. Through multiple steps of verification, the contaminants were identified from ink circles printed on the collection devices to indicate the positions and sizes of blood drops. Blood specimens from HPA-negative persons collected on these contaminated collection devices showed positive results in the fluorometric tests, but negative results in tandem mass spectroscopy (MS/MS) experiments. Contaminants on the collection devices could be extracted by 80% ethanol and showed an absorption peak around 245 nm, suggesting that these contaminants may contain benzene derivatives with similar structure to phenylalanine. High-performance liquid chromatography (HPLC) analysis of the ethanol extracts from contaminated collection devices identified two prominent peaks specifically from the devices. Methyl-2-benzoylbenzoate (MBB, CAS#606-28-0) was found as one of the major chemicals from contaminated collection devices. This report aims to remind colleagues in the field of this potential contamination and call for tighter regulation and quality control of specimen collection devices.

EVALUATION OF SCREENING TESTS FOR URINARY MUCOPOLYSACCHARIDES

PEDIATRICS ◽  
1973 ◽  
Vol 52 (1) ◽  
pp. 64-68
Author(s):  
Iraj Rezvani ◽  
P. J. Collipp ◽  
Angelo M. DiGeorge
Keyword(s):  
False Positive ◽  
Screening Test ◽  
False Positives ◽  
Spot Test ◽  
Screening Tests ◽  
Paper Test ◽  
Normal Children ◽  
Great Caution ◽  
Turbidity Test ◽  
Positive Results

A recently developed spot test, "MPS paper," has been added to other screening tests for urinary mucopolysaccharides. The effectiveness of this test has been compared to that of the cetytrimethylammonium bromide and the acid albumin gross turbidity tests in normal children and in patients with mucopolysaccharidoses. Although all these tests are effective in the detection of excessive mucopolysaccharides in urine, their excessive sensitivity yields many weak false-positives. We found "MPS paper" test to yield 34% false-positive tests, compared to 42% for cetytrimethylammonium bromide and 8% for the acid albumin gross turbidity test. We have concluded that the acid albumin gross turbidity is the most reliable screening test for detection of mucopolysaccharide disorders. "MPS paper" spot test has the advantage of being simple and practical, but weak positive results should be interpreted with great caution; it has the added disadvantage of being the most costly of the screening tests at the present time.

Tuberculosis as a cause of false-positive results in HIV screening EIA tests

1994 ◽  
Vol 75 (5) ◽  
pp. 394-395 ◽  
Author(s):  
Eduardo Werneck-Barroso ◽  
Afrânio Lineu Kritski ◽  
Maria Armanda M.S. Vieira ◽  
Carlos Eduardo Carvalho ◽  
Anna Cristina Carvalho ◽  
...  
Keyword(s):  
False Positive ◽  
Hiv Screening ◽  
Positive Results
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