Does a change in quality control results influence the sensitivity of an anti-HCV test?

2020 ◽  
Vol 58 (8) ◽  
pp. 1372-1380 ◽  
Author(s):  
Wayne J. Dimech ◽  
Giuseppe A. Vincini ◽  
Liza M. Cabuang ◽  
Megan Wieringa
Keyword(s):  
Quality Control ◽  
False Negative ◽  
External Quality Assessment Scheme ◽  
Clinical Sensitivity ◽  
Root Cause ◽  
Negative Results ◽  
False Negative Results ◽  
Three Samples ◽  
The Difference

AbstractBackgroundLaboratories use quality control (QC) testing to monitor the extent of normal variation. Assay lot number changes contribute the greatest amount of variation in infectious disease serology testing. An unexpected change in six lots of an anti-HCV assay allowed the determination of the effect these lot changes made to the assay’s clinical sensitivity.MethodsTwo sets of seroconversion samples comprising of 44 individual samples and 9 external quality assessment scheme (EQAS) samples, all positive to anti-HCV, were tested in affected and unaffected assay lots, and the difference in the quantitative and qualitative results of the samples was analyzed.ResultsOf 44 low-positive seroconversion samples tested in affected and unaffected assay lots, only three samples had results reported below the assay cutoff when tested on two of the six affected assay lot. A further sample had results below the cutoff for only one affected lot. None of the EQAS samples reported false-negative results. Samples having a signal to cutoff value of less than 6.0 generally had lower results in the affected lots compared with the unaffected lots.ConclusionsUnexpected changes in QC reactivity related to variation, in particular assay lot changes, may affect patient results. This study demonstrated that QConnect Limits facilitated the detection of an unexpectedly large variation in QC test results, allowed for the identification of the root cause of the change, and showed that the risk associated with the change was low but credible. The use of evidence-based QC program is essential to detect changes in test systems.

scholarly journals A Reliable, Label Free Quality Control Method for the Production of DNA Microarrays with Clinical Applications

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 340
Author(s):  
Elisa Chiodi ◽  
Francesco Damin ◽  
Laura Sola ◽  
Lucia Ferraro ◽  
Dario Brambilla ◽  
...  
Keyword(s):  
Quality Control ◽  
Dna Microarrays ◽  
Control Method ◽  
False Negative ◽  
Label Free ◽  
Negative Results ◽  
System A ◽  
Quality Control Method ◽  
False Negative Results ◽  
Imaging Sensor

The manufacture of a very high-quality microarray support is essential for the adoption of this assay format in clinical routine. In fact, poorly surface-bound probes can affect the diagnostic sensitivity or, in worst cases, lead to false negative results. Here we report on a reliable and easy quality control method for the evaluation of spotted probe properties in a microarray test, based on the Interferometric Reflectance Imaging Sensor (IRIS) system, a high-resolution label free technique able to evaluate the variation of the mass bound to a surface. In particular, we demonstrated that the IRIS analysis of microarray chips immediately after probe immobilization can detect the absence of probes, which recognizably causes a lack of signal when performing a test, with clinical relevance, using fluorescence detection. Moreover, the use of the IRIS technique allowed also to determine the optimal concentration of the probe, that has to be immobilized on the surface, to maximize the target recognition, thus the signal, but to avoid crowding effects. Finally, through this preliminary quality inspection it is possible to highlight differences in the immobilization chemistries. In particular, we have compared NHS ester versus click chemistry reactions using two different surface coatings, demonstrating that, in the diagnostic case used as an example (colorectal cancer) a higher probe density does not reflect a higher binding signal, probably because of a crowding effect.

scholarly journals Unexplained False Negative Results in Noninvasive Prenatal Testing: Two Cases Involving Trisomies 13 and 18

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
R. Hochstenbach ◽  
G. C. M. L. Page-Christiaens ◽  
A. C. C. van Oppen ◽  
K. D. Lichtenbelt ◽  
J. J. T. van Harssel ◽  
...  
Keyword(s):  
False Negative ◽  
Prenatal Testing ◽  
High Sensitivity ◽  
Trisomy 13 ◽  
Maternal Weight ◽  
Noninvasive Prenatal Testing ◽  
Root Cause ◽  
Negative Results ◽  
False Negative Results ◽  
Negative Case

Noninvasive prenatal testing (NIPT) validation studies show high sensitivity and specificity for detection of trisomies 13, 18, and 21. False negative cases have rarely been reported. We describe a false negative case of trisomy 13 and another of trisomy 18 in which NIPT was commercially marketed directly to the clinician. Both cases came to our attention because a fetal anatomy scan at 20 weeks of gestation revealed multiple anomalies. Karyotyping of cultured amniocytes showed nonmosaic trisomies 13 and 18, respectively. Cytogenetic investigation of cytotrophoblast cells from multiple placental biopsies showed a low proportion of nontrisomic cells in each case, but this was considered too small for explaining the false negative NIPT result. The discordant results also could not be explained by early gestational age, elevated maternal weight, a vanishing twin, or suboptimal storage or transport of samples. The root cause of the discrepancies could, therefore, not be identified. The couples involved experienced difficulties in accepting the unexpected and late-adverse outcome of their pregnancy. We recommend that all parties involved in caring for couples who choose NIPT should collaborate to clarify false negative results in order to unravel possible biological causes and to improve the process of patient care from initial counseling to communication of the result.

Liquid-chromatographic evaluation of age-related changes in the urinary excretion of free catecholamines in pediatric patients.

1984 ◽  
Vol 30 (2) ◽  
pp. 301-303 ◽  
Author(s):  
T G Rosano
Keyword(s):  
Urinary Excretion ◽  
Pediatric Patients ◽  
False Negative ◽  
Age Groups ◽  
Reference Intervals ◽  
Clinical Sensitivity ◽  
Negative Results ◽  
Age Related ◽  
False Negative Results ◽  
Liquid Chromatographic

Abstract Pediatric patients (to age 18) without neuroblastoma show an age-related decrease in urinary excretion of each of the catecholamines--epinephrine, norepinephrine, and dopamine--in relation to creatinine excretion. From these data, I have developed reference intervals for pediatric age groups. Application of these ranges to seven patients with neuroblastoma and ganglioneuroblastoma indicated a high clinical sensitivity for the urinary dopamine determination but significant false-negative results for epinephrine and norepinephrine.

False-negative results in the immunoassay analysis of drugs of abuse: can adulterants be detected by sample check test?

2017 ◽  
Vol 55 (3) ◽  
pp. 348-354 ◽  
Author(s):  
Barbara Matriciani ◽  
Bernd Huppertz ◽  
Ruprecht Keller ◽  
Ralf Weiskirchen
Keyword(s):  
Drugs Of Abuse ◽  
Methadone Treatment ◽  
False Negative ◽  
Urine Samples ◽  
Morphine Sulphate ◽  
Negative Results ◽  
Health Authorities ◽  
False Negative Results ◽  
Three Samples ◽  
Immunological Assays

Background The dilution or adulteration of urine is a serious problem in drugs of abuse testing. Tests to identify adulteration are currently available. This study investigated the ability of the CEDIA® sample check to detect adulteration. Methods Eight different drugs of abuse were added to a urine sample obtained from a healthy, drug-free subject: 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP), 3,4-methylenedioxyamphetamine, benzoylecgonine, D-amphetamine sulphate, ethyl-D-glucuronide, morphine sulphate, oxazepam, (-)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol. Urine samples were diluted to yield three samples of drugs of abuse concentrations close to general cut-offs as used in methadone treatment centres, by health authorities for psychological tests and in traffic medicine. Aspirin, citric acid, CrO3, H2O2, soap, sodium metaborate, vitamin C were added in three, HCl and NaOH in one, and NaN3 in two concentrations. All samples were measured with commercially available immunological assays shortly after sample preparation and 24 h later. All samples were further analysed with the CEDIA® sample check reaction which may identify adulteration. Results Oxidizing reagents (H2O2 or CrO3) are most effective in interfering in the measurement of benzoylecgonine, EDDP, ethyl-D-glucuronide and morphine sulphate. The measurement of (-)-11-nor-9-carboxy-Δ9-tetrahydrocannabinol is affected by many adulterants. Adulteration with HCl and NaOH was identified with the sample check reaction. NaN3 generated false negative results for a number of drugs of abuse. Conclusions Urine samples with drugs of abuse concentrations above cut-offs can be successfully tampered with adulterants in a way which cannot be detected with the CEDIA® sample check assay.

scholarly journals Clinical Performance of SARS-CoV-2 Molecular Testing

2020 ◽  
Author(s):  
Daniel A. Green ◽  
Jason Zucker ◽  
Lars F. Westblade ◽  
Susan Whittier ◽  
Hanna Rennert ◽  
...  
Keyword(s):  
Clinical Performance ◽  
Severe Disease ◽  
False Negative ◽  
Molecular Testing ◽  
Repeat Testing ◽  
Clinical Sensitivity ◽  
Initial Testing ◽  
Molecular Assays ◽  
Negative Results ◽  
False Negative Results

AbstractMolecular testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the gold standard for diagnosis of coronavirus disease 2019 (COVID-19), but the test clinical performance is poorly understood. From 3/10/2020-5/1/2020 NewYork-Presbyterian laboratories performed 27,377 SARS-CoV-2 molecular assays from 22,338 patients. Repeat testing was performed in 3,432 patients, of which 2,413 had negative and 1,019 had positive first day results. Repeat-tested patients were more likely to be older, male, African-American or Hispanic, and to have severe disease. Among the patients with initially negative results, 18.6% became positive upon repeat-testing. Only 58.1% of any-time positive patients had a result of “detected” on the first test. The clinical sensitivity of COVID-19 molecular assays is estimated between 66.2 % and 95.6%, depending on the unknown number of false negative results in single-tested patients. Conversion to a negative result is unlikely to occur before 15 to 20 days after initial testing or 20-30 days after the onset of symptoms, with 50% conversion occurring at 28 days after initial testing. Forty-nine initially-positive patients converted to negative and then back to positive in subsequent days. Conversion from first day negative to positive results increased linearly with each day of testing, reaching 25% probability in 20 days. In summary, our study provides estimates of the clinical performance of SARS-CoV-2 molecular assays and suggests time frames for appropriate repeat testing, namely 15 to 20 days after a positive test and the same or next 2 days after a negative test in a patient with high suspicion for COVID-19.

Microplate biochemical determination of Russian VX: Influence of admixtures and avoidance of false negative results

2012 ◽  
Vol 424 (2) ◽  
pp. 108-113 ◽  
Author(s):  
Daria S. Prokofieva ◽  
Richard O. Jenkins ◽  
Nikolay V. Goncharov
Keyword(s):  
False Negative ◽  
Negative Results ◽  
False Negative Results

scholarly journals Dynamics and Considerations in the Determination of the Excretion of Gluten Immunogenic Peptides in Urine: Individual Variability at Low Gluten Intake

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2624
Author(s):  
Laura Coto ◽  
Carolina Sousa ◽  
Angel Cebolla
Keyword(s):  
Celiac Disease ◽  
False Negative ◽  
Individual Variability ◽  
Lateral Flow Immunoassay ◽  
Gluten Free ◽  
Negative Results ◽  
Immunogenic Peptides ◽  
False Negative Results ◽  
Healthy Participants

Background: A lifelong strict gluten-free diet is the only available treatment for celiac disease, but total exclusion of gluten is difficult to achieve. The aim of this study was to determine the range of time and the amount of gluten immunogenic peptides (GIP) excreted in urine after specific gluten ingestions. Methods: 20 healthy participants followed the same diet for 12 days in which 50 mg and 2 g of gluten were ingested and all the urinations were collected. GIP were analyzed by lateral flow immunoassay (LFIA) tests and quantified using an LFIA reader. Results: GIP were detected in 15% and 95% of participants after 50 mg and 2 g gluten intakes, respectively. The higher frequency and concentration of GIP was found between 6 and 9 h after both gluten ingestions. The ranges of detection were 3–12 h (50 mg) and 0–15 h (2 g). Conclusions: An increase in the frequency of urine tests may be a suitable approach to avoid false negative results. The use of the LFIA test in three urine samples collected at different times may show a sensitivity of 19.6% for a gluten ingestion like 50 mg, increasing to 93% after 2 g consumption.

scholarly journals 68GA-PSMA — LABELED BIOMARKER FOR POSITRON EMISSION TOMOGRAPHY (LITERATURE REVIEW)

2018 ◽  
Vol 5 (5) ◽  
pp. 46-52
Author(s):  
M. D. Poyda ◽  
D. V. Ryzhkova ◽  
A. A. Stanzhevsky
Keyword(s):  
False Negative ◽  
Malignant Neoplasms ◽  
Diagnostic Efficiency ◽  
Negative Results ◽  
Tumor Focus ◽  
Positron Emission ◽  
False Negative Results ◽  
Pet Ct ◽  
Risk Patients

The review is devoted to the analysis of the diagnostic efficiency of combined positron emission and computed tomography (PET / CT) with the radiopharmaceutical 68Ga-PSMA in the initial staging of prostate cancer in middle- and high-risk patients, the determination of the tumor focus in the biochemical recurrence of the disease, and monitoring the effectiveness of systemic and radionuclide therapy. The causes of false positive and false negative results of PET / CT are listed and indications for the procedure are presented as well. 68Ga-PSMA diagnostic possibilities as a labeled biomarker of neovascularization in malignant neoplasms of other localizations are briefly described.

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