Reduction Of False-positive Results Research Articles

Use of in silico and in vitro methods as a potential new approach methodologies (NAMs) for (photo)mutagenicity and phototoxicity risk assessment of agrochemicals

The increased use of agrochemicals raises concerns about environmental, animal, and mainly human toxicology. The development of New Approach Methodologies (NAMs) for toxicological risk assessment including new in vitro tests and in silico protocols is encouraged. Although agrochemical mutagenicity testing is well established, a complementary alternative approach may contribute to increasing reliability, with the consequent reduction of false-positive results that lead to unnecessary use of animals in follow-up in vivo testing. Additionally, it is unreasonable to underestimate the phototoxic effects of an accidental dermal exposure to agrochemicals during agricultural work or domestic application in the absence of adequate personal protection equipment, especially in terms of photomutagenicity. In this scenario, we addressed the integration of in vitro and in silico techniques as NAMs to assess the mutagenic and phototoxic potential of agrochemicals. In the present study we used the yno1 S. cerevisiae strain as a biomodel for in vitro assessment of agrochemical mutagenicity, both in the absence and in the presence of simulated sunlight. In parallel, in silico predictions were performed using a combination of expert rule-based and statistical-based models to assess gene mutations and phototoxicity. None of the tested agrochemicals showed mutagenic potential in the two proposed approaches. The Gly and 2,4D herbicides were photomutagenic in the in vitro yeast test despite the negative in silico prediction of phototoxicity. Herein, we demonstrated a novel experimental approach combining both in silico and in vitro experiments to address the complementary investigation of the phototoxicity and (photo)mutagenicity of agrochemicals. These findings shed light on the importance of investigating and reconsidering the photosafety assessment of these products, using not only photocytotoxicity assays but also photomutagenicity assays, which should be encouraged.

Reduction in Newborn Screening False Positive Results Following a New Collection Protocol: a Quality Improvement Project.

Premature infants are known to have a higher rate of false positive newborn screening (NBS) results, with TPN as a contributing factor. The purpose of this quality improvement (QI) project is to reduce false positive NBS results via a TPN interruption protocol. A multidisciplinary team reviewed the literature and developed a new NBS collection protocol, which was implemented in 2 periods. In period 1, TPN was interrupted for 4 hours before NBS sample collection and initiation of carnitine supplements was avoided. In period 2, TPN was interrupted for 6 hours for infants birth weight (BW) < 1000 g, carnitine supplementation continued to be avoided. The rates of false positives NBS results were compared pre- and post-interventions in periods 1 and 2. Four hundred twelve neonates were evaluated prior to implementation of this QI project (July 2013-June 2014) and 414 during period 1 intervention (July 2014-June 2016). False positive results decreased from 20.6% to 11.4% (p < 0.001) among all BW categories following the 4-hour TPN interruption. The rate of false positives was further reduced among infants < 1000 g (p = 0.035) in period 2 (n = 112), including a significant reduction in false positive results with elevated amino acid profiles (p = 0.005). The implementation of a strict NBS collection protocol reduced false positive NBS results, which potentially can improve patient care by reducing unnecessary laboratory draws, pain, and parental anxiety. Interruption of TPN for 6 hours was significant in reducing NBS false positive results in neonates < 1000 g.

Effectiveness of Neonatal Hearing Screening System: A 12-Year Single Centre Study in the Czech Republic

PurposeThe study aims to evaluate the number of examined newborns and the results of screening for twelve years (2008–2019) and to assess the effectiveness of the established system of neonatal hearing screening. Design and methodsThe study was designed as a retrospective longitudinal data analysis. The data included all the children (19,043) born in the hospital and also children (74) transferred from other healthcare facilities. A total of 19,117 children were included in the research group. ResultsIn the first three years, a higher number of children did not pass the hearing screening, which was followed by a declining trend in the following years. After the first year of screening (2008), there was an improvement in diagnosis linked with a decrease in false-positive screening results (from 9.4% to 6.4%; p = 0.002). From 2008 to 2015, the ratio of children with positive screening to those with negative screening had a steady or declining trend. ConclusionsThe results showed a reduction in false-positive results after the first year of the screening program, probably due to improved care management and a gradual increase in the skills of the nurses performing the screening. Practice implicationsThe cornerstones of neonatal hearing screening are a sufficient number of trained neonatology nurses, their mutual substitutability and the availability of a hearing screening device in the newborn ward every day. The results imply the importance of periodic evaluation of the obtained data, enabling early detection of possible deficiencies in the hearing screening system.

Second Tier Molecular Genetic Testing in Newborn Screening for Pompe Disease: Landscape and Challenges.

Pompe disease (PD) is screened by a two tier newborn screening (NBS) algorithm, the first tier of which is an enzymatic assay performed on newborn dried blood spots (DBS). As first tier enzymatic screening tests have false positive results, an immediate second tier test on the same sample is critical in resolving newborn health status. Two methodologies have been proposed for second tier testing: (a) measurement of enzymatic activities such as of Creatine/Creatinine over alpha-glucosidase ratio, and (b) DNA sequencing (a molecular genetics approach), such as targeted next generation sequencing. (tNGS). In this review, we discuss the tNGS approach, as well as the challenges in providing second tier screening and follow-up care. While tNGS can predict genotype-phenotype effects when known, these advantages may be diminished when the variants are novel, of unknown significance or not discoverable by current test methodologies. Due to the fact that criticisms of screening algorithms that utilize tNGS are based on perceived complexities, including variant detection and interpretation, we clarify the actual limitations and present the rationale that supports optimizing a molecular genetic testing approach with tNGS. Second tier tNGS can benefit clinical decision-making through the use of the initial NBS DBS punch and rapid turn-around time methodology for tNGS, that includes copy number variant analysis, variant effect prediction, and variant ‘cut-off’ tools for the reduction of false positive results. The availability of DNA sequence data will contribute to the improved understanding of genotype-phenotype associations and application of treatment. The ultimate goal of second tier testing should enable the earliest possible diagnosis for the earliest initiation of the most effective clinical interventions in infants with PD.

Third- to Fourth-Generation HIV Testing: Reduction in False-Positive Results With the New Way of Testing, the Corporal Michael J. Crescenz Veteran Affairs Medical Center (CMCVAMC) Experience

Third- to Fourth-Generation HIV Testing: Reduction in False-Positive Results With the New Way of Testing, the Corporal Michael J. Crescenz Veteran Affairs Medical Center (CMCVAMC) Experience

Age‐adjusted D‐dimer cut‐off leads to more efficient diagnosis of venous thromboembolism in the emergency department: a comparison of four assays

Background The study compares different D-dimer assays and age-adjusted cut-offs in outpatients with suspected venous thromboembolism (VTE). The plasma concentration of this sensitive biomarker is increased by activated coagulation, but also by several conditions that are linked to an increased risk of VTE. One such condition is old age, which poses a common clinical problem where many prefer not to analyze D-dimer in elderly patients. Age-adjusted cut-offs have been validated for both deep venous thrombosis (DVT) and pulmonary embolism, aiming to increase specificity without notably decreasing sensitivity. Objectives We evaluated four common D-dimer assays in parallel, with and without applying age-adjusted cut offs for VTE. Patients/methods The prospective single-center study was conducted in 940 outpatients attending the emergency department with clinically suspected pulmonary embolism or DVT. Four automated D-dimer assays were compared (Siemens INNOVANCE® , Roche Tina-quant, Medirox MRX and STA® -Liatest® D-Di PLUS). Results All assays performed with areas under the ROC curve (AUC) > 0.9 and maintained their sensitivities after implementation of age-adjusted cut-offs. Specificities increased by 6-7% and number needed to test decreased by < 0.3. The rate of false positive results decreased by 6% overall and by 10-20% for patients ≥ 70. Conclusions Age-adjusted cut-offs resulted in maintained high sensitivity and a modest improvement in specificity and number needed to test for all evaluated D-dimer assays. There was a significant reduction in false positive results, which reflects avoidable unnecessary imaging without any compromise of clinical safety. This suggests a potential to benefit the management of VTE in elderly patients, both clinically and economically.

Lung cancer segmentation and diagnosis of lung cancer staging using MEM (modified expectation maximization) algorithm and artificial neural network fuzzy inference system (ANFIS)

Medical image processing plays a major role in advancing treatment planning, identification of disease and guiding for surgery. Lung cancer is one among the dangerous diseases that leads to death of most human beings due to uncontrolled growth in the cell. This research area is finding more importance among researchers is that because the available methods for lung cancer detection are very painful. So the automatic detection of lung nodule of computer tomography (CT) is finding more importance among researchers. Though there are a number of methods available for segmentation of lung nodules each method has its drawbacks because of the divergence that exists in lung nodule. The proposed method is the detection of lung nodules using MEM algorithm and classification is based on Artificial Neural Network Fuzzy Inference System (ANFIS) experimental results illustrate in an improvement of accuracy and reduction of false positive results. A comparative analysis is performed with FCM and FLICM algorithms to show the superior nature of MEM.

The Application of Voltammetric Analysis of Δ(9) -THC for the Reduction of False Positive Results in the Analysis of Suspected Marijuana Plant Matter.

The development of methodologies using inexpensive, fast, and reliable instrumention is desirable in illicit drug analysis. The purpose of this study was based on cyclic voltammetry technique to differentiate the electrochemical behavior of ∆(9) -THC, the psychoactive substance in marijuana, and five different extract plants to yield false positive results after analysis protocol for cannabinoids using thin-layer chromatography and Fast Blue B salt. After applying a deposition potential of -0.5 V in a glassy carbon working electrode, the results indicated an anodic peak current at 0.0 V versus Ag/AgCl after addition of ∆(9) -THC solution in the electrochemical cell, and limits of detection and quantification were 1.0 ng mL(-1) and 3.5 ng mL(-1) , respectively. Other interfering plants showed distinct amperometric responses. This methodology was useful to detect ∆(9) -THC even in the presence of the Fast Blue B salt, which avoided false positive results for all the studied extract plants.

Reduction in newborn screening metabolic false-positive results following a new collection protocol

Newborn screening includes testing for many metabolic diseases. False-positive results are higher among neonatal intensive care unit infants, resulting in increased confirmatory testing and family stress. Amino acid administration as a component of total parenteral nutrition is commonly used in the neonatal intensive care unit and suggested as a factor increasing false-positive results. The purpose of this study was to investigate the impact of a new sample collection protocol on false-positive results. This was a 2-year retrospective cohort study. Infants were grouped by birth year into pre- and postprotocol implementation and stratified by birth weight category. In 2010, newborn screening samples were collected from all infants regardless of total parenteral nutrition administration. In 2011, the protocol was changed, and total parenteral nutrition was replaced with 10% dextrose in water (D10W) for 3 h before sample collection. Data from 539 neonatal intensive care unit admissions were reviewed. The new protocol reduced false-positive results for each birth weight group by at least 50% and overall by 74% (P = 0.008). The odds of having a false-positive result preintervention were 3.87 times higher than postintervention. The protocol reduced estimated costs by >80%. A protocol interrupting total parenteral nutrition for 3 h before newborn screening collection resulted in a 74% reduction in false-positive results in a neonatal intensive care unit.

The reconstructed skin micronucleus assay in EpiDerm™: Reduction of false-positive results – a mechanistic study with epigallocatechin gallate

The high rate of false-positive or misleading results in in vitro mammalian genotoxicity testing is a hurdle in the development of valuable chemicals, especially those used in cosmetics, for which in vivo testing is banned in the European Union. The reconstructed skin micronucleus (RSMN) assay in EpiDerm™ (MatTek Corporation, USA) has shown promise as a follow-up for positive in vitro mammalian genotoxicity tests. However, few studies have explored its better predictive performance compared with existing in vitro assays. In the present study, we followed the protocol of the RSMN assay and used eight chemicals to compare micronucleus (MN) induction with EpiDerm™ with that in normal human epidermal keratinocytes (NHEKs), both derived from human skin. The assessments of EpiDerm™ conformed to those of in vivo MN assay, whereas those of NHEKs did not. The effect of cell differentiation status on MN induction was further addressed using a model compound, epigallocatechin gallate (EGCG), which is a major component of green tea extract that shows positive results in in vitro mammalian genotoxicity assays via oxidative stress and negative results in in vivo MN studies. RSMN assay in an underdeveloped epidermal model, EpiDerm-201™ (MatTek Corporation), showed a negative result identical to that in EpiDerm™, indicating that the barrier function of keratinocytes has limited impact. Analysis of the gene expression profile of both EpiDerm™ and NHEKs after EGCG treatment for 12h revealed that the expression of genes related to genotoxic response was significantly induced only in NHEKs. Conversely, antioxidative enzyme activities (catalase and glutathione peroxidase) in EpiDerm™ were higher than those in NHEKs. These results indicate that EpiDerm™ has antioxidant properties similar to those of a living body and is capable of eliminating oxidative stress that may be caused by EGCG under in vitro experimental conditions.

FUT2 and FUT3 genotype determines CA19-9 cut-off values for detection of cholangiocarcinoma in patients with primary sclerosing cholangitis

Allelic variants of fucosyltransferases 2 and 3 (FUT2/3) influence serum levels of CA19-9, a screening parameter commonly used for detection of biliary malignancy in PSC. We aimed at improving diagnostic accuracy of CA19-9 by determining the impact of FUT2/3 genotypes. CA19-9 levels were measured in 433 PSC patients, 41 of whom had biliary malignancy. Genotypes for FUT3 and FUT2 were used to assign patients to one of three groups: A, no FUT3 activity regardless of FUT2 activity; B, both FUT2 and FUT3 activity and C, no FUT2 activity without loss of FUT3 activity. Group-specific cut-off values were determined by Youden's index. The median CA19-9 values of cancer-free patients were significantly different (p<0.001) in Groups A (2.0U/ml), B (17.0U/ml), and C (37.0U/ml). Biliary malignancy patients in Groups B and C had significantly higher CA19-9 values than cancer-free patients (p<0.001). The optimal cut-off, as determined by ROC analysis, for all patients was 88.5U/ml. Optimal cut-off values in Groups A, B, and C were 4.0U/ml, 74.5U/ml, and 106.8U/ml, respectively. Use of these values improved sensitivity of CA19-9 in Groups B and C. Further, use of group-dependent cut-off values with 90% sensitivity resulted in a 42.9% reduction of false positive results. Use of FUT2/3 genotype-dependent cut-off values for CA19-9 improved sensitivity and reduced the number of false positive results.

Methionine/galactose ratio on newborn blood spots useful for reduction of false positives for homocystinuria and galactosemia by high-performance anion-exchange chromatography with pulsed amperometric detection

BackgroundMethionine (Met) in blood and urine is a useful diagnostic marker for homocystinuria (HCU). However, galactosemia could be misdiagnosed as HCU when Met is used as the sole marker, since elevated excretion of Met presents in both galactosemia and HCU. Use of a more specific diagnostic marker in addition to Met is therefore necessary for reduction of false positive results for HCU as well as confirmative diagnosis of HCU. MethodsChromatographic separation was performed using an anion-exchange column. The levels of Met and galactose (Gal) on blood were measured and Met/Gal ratios were calculated from blood spot samples from 300 normal volunteers, eight galactosemia patients, and three HCU patients. ResultsThe Met/Gal ratio ranged 0–4.95 for normal blood spots (n=300), 0–0.22 for galactosemia samples (n=8), and >1250 for HCU patient samples. ConclusionsSeparation, extraction, and deproteinization procedures were established for Met and Gal in blood spots. And Met/Gal ratio allowed HCU to clearly distinguish from galactosemia. As a way of second tier confirmative analysis, the ratio is the best way to reduce false positives. The assay is most appropriate to reduce false positives in labs that do not screen for galactosemia.

Reduction in False-Positive Results after Introduction of Digital Mammography: Analysis from Four Population-based Breast Cancer Screening Programs in Spain

To evaluate the effect of the introduction of digital mammography on the recall rate, detection rate, false-positive rate, and rates of invasive procedures in a cohort of women from four population-based breast cancer screening programs in Spain. The study was approved by the ethics committee; informed consent was not required. A total of 242,838 mammograms (171,191 screen film [screen-film mammography group] and 71,647 digital [digital mammography group]) obtained in 103,613 women aged 45-69 years were included. False-positive results for any additional procedure and for invasive procedures, the breast cancer rate, and the positive predictive value in each group were compared by using Pearson χ(2) test. The effect of the mammographic technology used (screen-film or digital) on the false-positive results and cancer detection risk was evaluated with multivariate logistic regression models, adjusted according to women's and the screening program's characteristics and time trends. The false-positive rate was higher for screen-film than for digital mammography (7.6% and 5.7%, respectively; P < .001). False-positive results after an invasive procedure were significantly higher for screen-film than for digital mammography (1.9% and 0.7%, respectively; P < .001). No significant differences were observed in the overall cancer detection rate between the two groups (0.45% and 0.43% in the screen-film and digital mammography groups, respectively; P = .59). The adjusted risk of a false-positive result was higher for screen-film than for digital mammography (odds ratio = 1.32). The adjusted risk was also lower for the digital mammography group when time trends were taken into account. The lower false-positive risk with use of digital mammography should be taken into account when balancing the risks and benefits of breast cancer screening.

The additional value of an oblique image plane for MRI of the anterior and posterior distal tibiofibular syndesmosis

ObjectiveThe optimal MRI scan planes of collateral ligaments of the ankle have been described extensively, with the exception of the syndesmotic ligaments. We assessed the optimal scan plane for depicting the distal tibiofibular syndesmosis.Materials and MethodsIn order to determine the optimal oblique caudal-cranial and lateral-medial MRI scan plane, two fresh frozen cadaveric ankles were used. The angle of the scan plane that demonstrated the anterior and posterior distal tibiofibular ligament uninterrupted in their full length was determined. In a prospective study this oblique scan plane was then used in addition to the axial and coronal planes, for MRI scans of both ankles in 21 healthy volunteers. Two observers independently evaluated the anterior tibiofibular ligament (ATIFL) and posterior tibiofibular ligament (PTIFL) regarding the continuity of the individual fascicles, thickness and wavy contour of the ligaments in both the axial and the oblique plane. Kappa was calculated to determine the interobserver agreement. McNemar’s test was used to statistically quantify the significance of the two scan planes.ResultsIn the axial plane the ATIFL was in 31% (13/42) partly and in 69% (29/42) completely discontinuous; in the oblique plane the ATIFL was continuous in 88% (37/42) and partly discontinuous in 12% (5/42). Compared with the axial plane, the oblique plane demonstrated significantly less discontinuity (p < 0.001), but not significantly less thickening (p = 1.00) or less wavy contour (p = 0.06) of the ATIFL. In the axial scan plane the PTIFL was continuous in 76% (32/42), partially discontinuous in 19% (8/42) and completely discontinuous in 5% (2/42); in the oblique plane the PTIFL was continuous in 100% (42/42). Compared with the axial plane, the oblique plane demonstrated significantly less discontinuity (p = 0.002), but not significantly less thickening (p = 1.00) or less wavy contour (p = 0.50) of the PTIFL. The interobserver agreement score and kappa (κ) regarding the continuity for the ATIFL in the axial and oblique planes was 91% (κ = 0.79) and 91% (κ = 0.55) respectively; for the PTIFL it was 86% (κ = 0.65) and 100% (κ = not defined).ConclusionThe ATIFL and PTIFL are routinuely scanned in the orthogonal planes. The advantage of MRI scanning in an oblique image plane of about 45 degrees permits a better evaluation of the ligaments compared with the axial plane, particularly a better interpretation of ligament continuity, thickening and wavy contour. This may lead to a reduction in false-positive results, especially regarding partial or complete ligament ruptures. This can be of considerable aid in therapeutic management.Electronic supplementary materialThe online version of this article (doi:10.1007/s00256-010-0938-9) contains supplementary material, which is available to authorized users

The improved specificity of bovine brucellosis testing in Great Britain

The brucellosis surveillance scheme in Great Britain includes the serological testing of approximately 1 million bovine samples per year. These are screened by iELISA, positives going forward for confirmatory testing by CFT and SAT. Samples positive by confirmatory testing prompt substantial field investigations and interventions, but the animals involved are usually uninfected. Described below are a series of modifications to the screening method, which have resulted in a 10-fold reduction in false positive results whilst maintaining sensitivity. The key modifications include the introduction of blocking agents, a change in serum test dilution and the introduction of a control that directly defines the positive/negative cut-off. These simple modifications have had a large impact in reducing the cost of the surveillance programme due to reductions in confirmatory test requirements and a knock on effect of reducing costly field intervention.

93 Utility of NT-BNP as a screening tool for cardiac dysfunction in patients with long-standing diabetes mellitus

Background: Cardiac dysflmction (CD) is common in patients with long-standing diabetes mellitus and can lead to heart failure or sudden death. N-Terminal pro-Brain Natriuretic Peptide (NT-proBNP) may provide a screening method for the early detection and treatment of patients with CD but is confounded by renal dysfunction. Aim: To assess the utility of NT-proBNP for detecting CD in patients over 50 years of age with long-standing (> 10 years) diabetes. Method: A standard clinical history, current medications, height and weight were recorded for all patients. They underwent a blood test for NT-proBNP, routine haematology and biochemistry, lung function tests, 12-lead ECG and echocardiography. Results were compared with 100 normal subjects. Results: We invited 144 consecutive patients attending a long-term follow-up clinic for diabetes. 109 consented to participate. 37 patients had known IHD, 9 had LVEF 30, 46 had moderate or severe LVH, 5 had moderate or severe valve disease and 5 had a glomemlar filtration rate (GFR) of 330pg/ml, the 95th centile of the control group. An NT-proBNP cut-off value of 135 pg/ml provided a test specificity (SP) of 62% at a sensitivity (SN) of 100% (AUC 0.888) for the detection of LVEF<40%. Correction of NTproBNP for GFR and age improved test performance (SP = 68%, SN = 100%, AUC = 0.895) with a cut off value of 152 pg/ml. However, a better test performance was obtained using piecewise decision rules (see Table 1) for NT-proBNP and GFR (SP - 78%, SN = 100%). For a population of 1000, this would give a 42.7% reduction in false positive results from 349 (based on NT-proBNP only) to 149, with no increase in the number of false negatives. Table 1. Optimal Decision Rules for Detection of LVEF < 40% Decision rule Test result