Rate Of False-positive Results Research Articles

Estimating neonatal screening for congenital hypothyroidism test performance

Introduction: Newborn screening (NBS) is a system of organized search in the entire neonatal population for specific diseases. In Bosnia and Herzegovina, two diseases are included in NBS, congenital hypothyroidism (CH), and phenylketonuria. The screening for CH is based on determination of thyroid stimulating hormone (TSH) levels in blood obtained by heel prick method. The aim of this study is to evaluate the effectiveness of NBS program for CH based on TSH and establish the mean age of diagnosis of CH.Methods: TSH was measured by time-resolved fluoroimmunoassay (DELFIA Neonatal hTSH kit). The TSH cutoff value was 9 μU/mL. Neonates with TSH < 9 μU/mL had a negative NBS result. Neonates with TSH ≥ 9 μU/mL were recalled for a confirmation test and thyroid hormones were determined from venous blood to establish diagnosis of CH.Results: A total of 24,351 neonates were subjected to NBS in our institution. A total of 164 newborns with TSH ≥ 9 μU/ml were sent to additional testing (mean recall rate of 0.68%) at a mean age of 11.4 ± 0.5 days of life. In this group, diagnosis of CH was confirmed in 22 neonates (13.41%). The mean rate of false positive results of NBS was 0.59%. The incidence of CH in Sarajevo Canton ranged from 1/2477 in 2018 to 1/641 in 2020. The mean incidence of CH over a 5-year period was 1/1085, while the mean age at the time of diagnosis was 16.5 ± 1.2 days.Conclusion: The analysis of NBS on congenital hypothyroidism data showed the satisfactory recall and false positive rate and indicated well selected TSH cutoff value. The mean age at the time of diagnosis assures early treatment and good neurological outcome in neonates with CH.

Abstract TMP59: Low Value Of Inherited Thrombophilia Testing Among Patients With Stroke Or Transient Ischemic Attack: A Single-institution Study

Background/Purpose: Inherited thrombophilia testing in the acute inpatient setting is controversial and expensive, and in many cases does not change clinical management. We sought to determine the value of inpatient inherited thrombophilia testing for patients who presented with an isolated acute ischemic stroke or transient ischemic attack (TIA) without concurrent venous thromboembolism. Methods: We retrospectively analyzed a database comprising patients who were admitted for acute ischemic stroke or TIA in 2019 at Thomas Jefferson University Hospitals in Philadelphia, PA and had inherited thrombophilia testing performed during the hospital admission. Charts were reviewed to determine stroke risk factors, test results, and clinical management. Results: The study included 102 patients (median age 49.0 years, 53.9% female) who presented with acute ischemic stroke or TIA (including branch and central retinal artery occlusions) and underwent inpatient testing for factor V Leiden, prothrombin G20210A variant, hyperhomocysteinemia, PAI-1 elevation, and deficiencies of protein C and S and antithrombin. 406 tests were ordered, among which 14.0% resulted abnormal, and 41.2% of patients had at least one abnormal test. Patients without stroke risk factors were more likely to have an abnormal result (60.0% vs 35.1%, P = .028). However, 40% of abnormal tests were borderline positive antigen or activity assays that likely represented false positives. Considering only definitively positive results, there was no significant difference in the likelihood of a positive test in patients with vs without stroke risk factors (32.0% vs 26.0%, P = .557) or those under vs over age 50 years (30.2% vs 24.5%, P = .519). No patients with an abnormal result had their clinical management changed as a result. Charges for the tests totaled $182,994 USD. Conclusions: Inpatient inherited thrombophilia testing immediately following isolated acute arterial ischemic stroke or TIA was associated with high rates of false positive results and was expensive. Positive results did not change clinical management in a single case.

The prediction of different phenotypes of preeclampsia in the first trimester of pregnancy (two-center retrospective study)

AIM: The aim of this study was to determine the effectiveness of predicting the development of placental or maternal preeclampsia (PE) by clinical and anamnestic risk factors and results of the combined screening in first trimester of pregnancy.
 MATERIALS AND METHODS: This two-center retrospective case-control study included the data analysis of somatic status, the obstetric and gynecologic anamnesis, and the results of the combined screening of 373 women in the first trimester of pregnancy. The control group consisted of 200 women with physiological course of pregnancy and labor. The main group comprised 173 patients whose pregnancy was complicated by early-onset (n = 44, 25%) or severe late-onset (n = 129, 75%) PE. We analyzed more than 100 clinical and anamnestic risk factors for PE implementation and evaluated the risk of developing PE at 11.0-13.6 weeks of gestation using the Fetal Medicine Foundation calculator.
 RESULTS: Maternal risk factors for PE development are identical for clinical phenotypes, except for the family anamnesis of arterial vascular accidents in first-line relatives under 45 years of age, which are significantly interfaced to risk of placental PE development (OR 6.38, 95% CI 2.002.28; p = 0.0017). A comprehensive assessment of clinical and anamnestic data at 11.0-13.6 weeks of gestation allows for predicting the implementation of maternal severe PE in 36.7% of cases and placental PE in 29.6% of cases with an identical false positive rate of 10.5%. Carrying out the combined screening in the first trimester allows for determining the risk of PE development up to 37 weeks without differentiation by clinical phenotypes, with a test sensitivity of 53.9% at a false positive rate of 34.7%.
 CONCLUSIONS: The prediction of placental or maternal PE development in the first trimester of pregnancy is possible only by maternal, clinical and anamnestic risk factors with a low predictive value of the test. Carrying out the combined screening with the inclusion of maternal risk factors, uterine artery pulsation index and pregnancy-associated plasma protein-A level increases the predictive value of the test for PE development up to 37 weeks from 37.6% to 53.6% at a high rate of false positive results. Validation of medical technologies for predicting clinical PE phenotypes in the population of women, taking into account a territorial origin and risk factors, will allow for defining the shortcomings of the model and improving its predictive value.

Can Any Drug Be Repurposed for Cancer Treatment? A Systematic Assessment of the Scientific Literature.

Simple SummaryDrug repurposing strategies utilize drugs, already approved by regulatory authorities, to test their efficacy against different diseases. While this approach is increasingly used, according to the literature, there are few systematic assessments of these efforts so far. In this work, we tried to answer the question: How many approved drugs show anti-cancer effects according to the literature? We found that the majority (69%) of the approved drugs we analyzed did show anti-cancer effects in preclinical studies. The assessment of the methodological quality of the reports, namely, the reporting quality and usage of bias-reducing methods, showed that the methodological quality of the articles was by and large moderate, while many items of the quality assessment were lacking in most reports (for example, blinding, preregistration, power calculations, and detailed information on lab animals). We hypothesize that the current reward systems favor positive results over high methodological quality, probably leading to many false-positive results.Drug repurposing is a complementary pathway for introducing new drugs against cancer. Broad systematic assessments of ongoing repurposing efforts in oncology are lacking, but may be helpful to critically appraise current and future efforts. Hence, we conducted a systematic PubMed search encompassing 100 frequently prescribed and 100 randomly selected drugs, and assessed the published preclinical anti-cancer effects. Furthermore, we evaluated all the identified original articles for methodological quality. We found reports indicating anti-cancer effects for 138/200 drugs, especially among frequently prescribed drugs (81/100). Most were reports suggesting single-agent activity of the drugs (61%). Basic information, such as the cell line used or control treatments utilized, were reported consistently, while more detailed information (e.g., excluded data) was mostly missing. The majority (56%) of in vivo studies reported randomizing animals, while only few articles stated that the experiments were conducted in a blinded fashion. In conclusion, we found promising reports of anti-cancer effects for the majority of the assessed drugs, but speculate that many of them are false-positive findings. Reward systems should be adjusted to encourage the widespread usage of high reporting quality and bias-reducing methodologies, aiming to decrease the rate of false-positive results, and thereby increasing the trust in the findings.

NeoSeq: a new method of genomic sequencing for newborn screening

ObjectiveTo explore the clinical application of NeoSeq in newborn screening.MethodsBased on the results obtained from traditional newborn screening (NBS) with tandem mass spectrometry (TMS), three cohorts were recruited into the present study: 36 true positive cases (TPC), 60 false-positive cases (FPC), and 100 negative cases. The dried blood spots of the infants were analyzed with NeoSeq, which is based on multiplex PCR amplicon sequencing.ResultsOverall, the sensitivity of NeoSeq was 55.6% (20/36) in the detection of TPC. NeoSeq detected disease-related genes in 20 of 36 TPC infants, while it could not identify these genes in eight children. Five cases (3.1%) with disease risk were additionally found in the FPC and NC cohorts. There was a significant difference in the diagnostic time between the two methods—10 days for NeoSeq vs. 43 days for traditional NBS.ConclusionsNeoSeq is an economic genomic screening test for newborn screening. It can detect most inborn errors of metabolism, reduce the rate of false positive results, shorten the porting cycles, and reduce the screening cost. However, it is still necessary to further optimize the panel design and add more clinically relevant genomic variants to increase its sensitivity.

Diagnostic performance of a novel digital immunoassay (RapidTesta SARS-CoV-2): A prospective observational study with nasopharyngeal samples

IntroductionDigital immunoassays are generally regarded as superior tests for the detection of infectious disease pathogens, but there have been insufficient data concerning SARS-CoV-2 immunoassays. MethodsWe prospectively evaluated a novel digital immunoassay (RapidTesta SARS-CoV-2). Two nasopharyngeal samples were simultaneously collected for antigen tests and Real-time RT-PCR. ResultsDuring the study period, 1127 nasopharyngeal samples (symptomatic patients: 802, asymptomatic patients: 325) were evaluated. For digital immunoassay antigen tests, the sensitivity was 78.3% (95% CI: 67.3%–87.1%) and the specificity was 97.6% (95% CI: 96.5%–98.5%). When technicians visually analyzed the antigen test results, the sensitivity was 71.6% (95% CI: 59.9%–81.5%) and the specificity was 99.2% (95% CI: 98.5%–99.7%). Among symptomatic patients, the sensitivity was 89.4% (95% CI; 76.9%–96.5%) with digital immunoassay antigen tests, and 85.1% (95% CI; 71.7%–93.8%) with visually analyzed the antigen test, respectively. ConclusionsThe sensitivity of digital immunoassay antigen tests was superior to that of visually analyzed antigen tests, but the rate of false-positive results increased with the introduction of a digital immunoassay device.

Cardiac Scintigraphy and Screening for Transthyretin Cardiac Amyloidosis: Caveat Emptor.

Cardiac Scintigraphy and Screening for Transthyretin Cardiac Amyloidosis: Caveat Emptor.

Venous capacitance and venous return in young adults with typical vasovagal syncope: a cross-sectional study

Vasovagal syncope (VVS) has a high prevalence in the general population and is associated with potential complications. There is limited information on the possible association between venous capacitance (VC) and...

SARS-CoV-2 detection by reverse transcriptase polymerase chain reaction testing: Analysis of false positive results and recommendations for quality control measures

Testing for SARS-CoV-2 has become a critical component for the management of the COVID-19 pandemic. Reverse transcriptase polymerase chain reaction (RT-PCR) assays are currently the predominate method for testing. Quality control (QC) measures utilize known positive and known negative controls to ensure the adequacy of extraction and RT-PCR steps but do not evaluate all components of testing. We have conducted a quality assurance review of our RT-PCR testing for COVID-19 to determine the rate of false positive results in asymptomatic patients and causes for these errors. DesignWe have developed a quality control procedure in which all specimens from asymptomatic unexposed persons with SARS-CoV-2 positive tests were retested. When a second test was “non-detected” a third test was performed and a root cause analysis of the erroneous result undertaken. ResultsIn the study period, 24,717 samples were tested and 6251 were from asymptomatic patients. Of the 288 initial positive tests, 20 (6.9%) were negative on retesting. Review of cycle threshold curves, technologists’ records, location of specimen on testing plates and relationships with high viral load specimens was undertaken. Analysis revealed technologists’ errors (misplacement of specimen in testing plate or contamination) and cross contamination from high viral load specimens in adjacent wells of testing plates were common causes for false positive results. DiscussionSARS-CoV-2 RT-PCR testing is associated with a small number of false positive results, most easily recognized in asymptomatic non-exposed patients. Implementation of a limited retesting protocol identifies clinically significant testing errors and allows review and improvement of laboratory procedures.

Validity of the "Structured Inventory of Malingered Symptomatology" [SIMS] in the Assessment of Healthy Individuals and Patients with Psychiatric Disorders Outside the Forensic Context

Assessment of the rate of false-positive results of the Structured Inventory of Malingered Symptomatology (SIMS) in healthy controls and authentic patients outside the forensic or rehabilitative context. Beyond the SIMS scores, further variables (PANSS, Hamilton scale, MMSE) were obtained. SIMS scores of healthy individuals were compared with the SIMS scores of the different groups of patients. Additionally, correlations between the SIMS scores and other variables were investigated. Patients with psychotic disorders (n=30) or depressive episodes (n=32) more frequently achieved SIMS scores >16 as compared to healthy controls. In comparison, patients with amnestic disorders (n=15) had inconspicuous SIMS scores. Depressed patients with positive SIMS results were significantly more likely to be diagnosed with another psychiatric disorder and the scores of these patients on the Hamilton scale were correlated with positive results on 2 subscales of the SIMS (NI, AF). If this instrument is to applied in clinical practice in the future, further validation of the SIMS is necessary. The specificity of the SIMS seems to be context-related.

Clinical Evaluation of an Improved Metagenomic Next-Generation Sequencing Test for the Diagnosis of Bloodstream Infections.

Metagenomic next-generation sequencing (mNGS) of plasma cell-free DNA has emerged as a promising diagnostic technology for bloodstream infections. However, a major limitation of current mNGS assays is the high rate of false-positive results due to contamination. We made novel use of 3 control groups-external negative controls under long-term surveillance, blood samples with a negative result in conventional tests, and a group of healthy people-that were combined and dedicated to distinguishing contaminants arising from specimen collection, sample processing, and human normal flora. We also proposed novel markers to filter out false-positive interspecies calls. This workflow was applied retrospectively to 209 clinical plasma samples from patients with suspected bloodstream infections. Every pathogen identified by the mNGS test was reviewed to assess the diagnostic performance of the workflow. Our mNGS workflow showed clinical sensitivity of 87.1%, clinical specificity of 80.2%, positive predictive value of 77.9%, and negative predictive value of 88.6% compared with the composite reference standard. Notably, mNGS showed great improvement in clinical specificity compared with the current test while keeping clinical sensitivity at a high level. The mNGS workflow with multiple control groups dedicated to distinguishing nonpathogen microbes from real causal pathogens has reducing false-positive results. This contribution, with its optimization of workflow and careful use of controls, can help mNGS become a powerful tool for identifying the pathogens responsible for bloodstream infections.

New alignment-based sequence extraction software (ALiBaSeq) and its utility for deep level phylogenetics.

Despite many bioinformatic solutions for analyzing sequencing data, few options exist for targeted sequence retrieval from whole genomic sequencing (WGS) data with the ultimate goal of generating a phylogeny. Available tools especially struggle at deep phylogenetic levels and necessitate amino-acid space searches, which may increase rates of false positive results. Many tools are also difficult to install and may lack adequate user resources. Here, we describe a program that uses freely available similarity search tools to find homologs in assembled WGS data with unparalleled freedom to modify parameters. We evaluate its performance compared to other commonly used bioinformatics tools on two divergent insect species (>200 My) for which annotated genomes exist, and on one large set each of highly conserved and more variable loci. Our software is capable of retrieving orthologs from well-curated or unannotated, low or high depth shotgun, and target capture assemblies as well or better than other software as assessed by recovering the most genes with maximal coverage and with a low rate of false positives throughout all datasets. When assessing this combination of criteria, ALiBaSeq is frequently the best evaluated tool for gathering the most comprehensive and accurate phylogenetic alignments on all types of data tested. The software (implemented in Python), tutorials, and manual are freely available at https://github.com/AlexKnyshov/alibaseq.

Diagnostic value of DWI-MRI for the detection of acute plaques in the relapse phase of multiple sclerosis

Background. The 2010 revision of the McDonald criteria, widely used for the diagnosis of multiple sclerosis (MS), has established that dissemination in time (DIT) can be demonstrated by the simultaneous presence of asymptomatic gadolinium-enhancing and non-enhancing plaques on a single magnetic resonance imaging (MRI). When the use of gadolinium contrast agents is contraindicated, diffusion-weighted imaging (DWI) is utilized to confirm diffusion alterations in active inflammatory plaques. This study intended to examine whether DWI can be a viable alternative to contrast-enhanced T1-weighted imaging for demonstrating DIT in MS. Material and methods.We assessed 30 previously diagnosed MS patients during acute relapse (based on the 2010 McDonald criteria) and evaluated their brain MRI via DWI‚ contrast-enhanced T1-weighted imaging, and FLAIR sequences. Asymptomatic plaques were defined as either hyperintense or non-hyperintense in DWI and enhancing or non-enhancing in T1GAD-MRI. Statistical indices for the prediction of plaque enhancement in T1 GAD-MRI via DWI-MRI were calculated and compared. Results. The 30 participants in our study had a total of 925 demyelinating plaques that were larger than 3mm in size and presented to be hyperintense in FLAIR-MRI. Diffusion hyperintensity and plaque enhancement were significantly correlated. The sensitivity‚ specificity, positive predictive value‚ negative predictive value, and accuracy of DWI were calculated to be 69.66%‚ 99.76%‚ 96.88%‚ 96.86%, and 96.86%, respectively. Conclusions. Hyperintense DWI findings do not necessarily overlap with contrast enhancements in T1 GAD-MRI. DWI was shown to produce a higher rate of false-positive results. Our study concludes that although T1 GAD-MRI should not be replaced by DWI to determine DIT due to its lower specificity, DWI’s continued use as a surrogate screening imaging sequence whenever the use of T1GAD-MRI is of concern is not without its merits.

Adoption of a non-invasive prenatal test (NIPT) in prenatal screening in Moscow: first results

The objective — To assess the effectiveness of including NIPT in the structure of prenatal diagnostics in Moscow. Material and Methods — Totally 5,181 pregnancies undergoing screening for fetal trisomy using NIPT during the period from 01.04.2020 to 30.09.2020 in Russia. According to the results of biochemical blood test, the patients were divided into two groups: group of high risk (cut-off ≥1:100) (n=208) and group of intermediate risk (cut-off 1:101 – 1:2500) (n=4,973). Patients at high-risk cell-free DNA (cfDNA) were offered an invasive procedure, followed by genetic analysis (cytogenetic or molecular karyotyping). Results — Among the analysed samples, 117 (2.3%) had a high risk of the following common fetal chromosome abnormalities by NIPT: trisomy 21 in 50 cases, trisomy 18 in 17 cases, trisomy 13 in 5 cases, and sex chromosome aneuploidy (SCA) in 22 cases. Additionally, rare autosomal trisomies and/or subchromosomal arrangements were revealed in 23 cases. We found associations between cfDNA concentration and high risk of aneuploidies (particularly trisomy 21) and fetal sex and between low fetal fraction (FF) and body mass index (BMI) as well as maternal weight. Additionally, a high risk of trisomy 21 was associated with the term gestation. Conclusion — The effectiveness of technological resources that are based on cfDNA testing for detecting abnormal fetal chromosome numbers and other chromosomal anomalies is high and reduce rates of false positive results. Therefore, NIPT should be more widely used as a first-line screening method.

Assessment of Campylobacter fetus subsp. venerealis molecular diagnosis using clinical samples of bulls

BackgroundCampylobacter fetus subsp. venerealis (Cfv) is the pathogen responsible for Bovine Genital Campylobacteriosis (BGC), a venereal disease of cattle associated with impaired reproductive performance. Although several PCR assays were developed to identify this pathogen, most of them are still poorly evaluated in clinical samples. This study evaluated real-time PCR assays for Cfv detection in preputial samples of bulls (n = 308).ResultsThe detection at the subspecies level (Cfv) compared four assays: two targeting ISCfe1 and two targeting parA gene. The detection at the species level (C. fetus) considered an assay targeting the nahE gene and a commercial kit for C. fetus identification. At the subspecies level, assays directed either to different targets (parA and ISCfe1), or to the same target (ISCfe1 or parA), showed a high percentage of disagreeing results. All samples positive at the subspecies level (n = 169) were negative in C. fetus detection assays, which strongly suggests the horizontal gene transfer of ISCfe1 and parA to other bacterial species. This was confirmed by microbiological isolation of three Campylobacter portucalensis strains responsible for false positive results. Sequences with a high level of identity with ISCfe1 and parA gene of Cfv were identified in C. portucalensis genome.ConclusionsOverall, this study reveals that PCR assays solely directed to a subspecies target originate a high rate of false positive results, due to the presence of parA and ISCfe1 homologous sequences in other bacterial species, namely of the genus Campylobacter. Although the specificity of these methods may be higher if applied to bulls from herds with clinical features of BGC or in other geographical regions, current PCR diagnosis should couple subspecies and species targets, and further research must be envisaged to identify Cfv specific molecular targets.

Microplastics identification by infrared spectroscopy – Evaluation of identification criteria and uncertainty by the Bootstrap method

The assessment of microplastic contamination in an environmental compartment involves identifying and counting microplastics in a representative fraction of the compartment. Microplastics can be identified by μFTIR spectroscopy where spectra are manually examined for characteristic polymer bands or by an automatic comparison of particle spectrum with reference spectra of polymers. The automatic spectra comparison can involve calculating a correlation coefficient, CC, between particle and reference spectra where a minimum correlation above which identification is adequately reliable should be defined. Correlation can be calculated from original or transformed signals, such as taking the first derivative, and by using unweighted or weighted CC. Weighted CC can highlight the spectral features more relevant to distinguish polymers. This work describes a methodology for setting the minimum CC, P5»P, associated with a true positive result rate, TP, of 95% and for checking if this threshold allows identifications with a false positive result rate, FP, not greater than 5%. This methodology was successfully applied to the use of various CC determined from original or transformed spectra for the identification of polyethylene, PE, and polypropylene, PP, microplastics in river sediments by μFTIR. The analytical portions of sediments were digested with H2O2 and microplastics separated from the remaining particles by density using a saturated NaCl solution. Pearson’s, Spearman’s and Alternative unweighted and weighted correlation coefficients were studied. The P5»P was estimated by the Bootstrap method that resamples spectra CC between a reference material and microparticle of the same polymer collected from the environment. This resampling allows simulating CC distribution required to estimate its 5th percentile (i.e. P5»P). The FP was estimated from the probability of a particle not from the same polymer type of the reference material producing a CC greater than P5»P. Some unweighted and weighted CC determined from original or transformed spectra were successfully used to identify PE or PP particles in river sediments. More particle spectra need to be collected to ensure performance is assessed from a representative diversity of aged polymers with different additives. The spreadsheets used for CC calculations and Bootstrap simulations are made available and can be used for the validation of the identification of other polymer types by μFTIR or ATR-FTIR spectroscopy.

MCCS: a novel recognition pattern-based method for fast track discovery of anti-SARS-CoV-2 drugs.

Given the scale and rapid spread of the coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, or 2019-nCoV), there is an urgent need to identify therapeutics that are effective against COVID-19 before vaccines are available. Since the current rate of SARS-CoV-2 knowledge acquisition via traditional research methods is not sufficient to match the rapid spread of the virus, novel strategies of drug discovery for SARS-CoV-2 infection are required. Structure-based virtual screening for example relies primarily on docking scores and does not take the importance of key residues into consideration, which may lead to a significantly higher incidence rate of false-positive results. Our novel in silico approach, which overcomes these limitations, can be utilized to quickly evaluate FDA-approved drugs for repurposing and combination, as well as designing new chemical agents with therapeutic potential for COVID-19. As a result, anti-HIV or antiviral drugs (lopinavir, tenofovir disoproxil, fosamprenavir and ganciclovir), antiflu drugs (peramivir and zanamivir) and an anti-HCV drug (sofosbuvir) are predicted to bind to 3CLPro in SARS-CoV-2 with therapeutic potential for COVID-19 infection by our new protocol. In addition, we also propose three antidiabetic drugs (acarbose, glyburide and tolazamide) for the potential treatment of COVID-19. Finally, we apply our new virus chemogenomics knowledgebase platform with the integrated machine-learning computing algorithms to identify the potential drug combinations (e.g. remdesivir+chloroquine), which are congruent with ongoing clinical trials. In addition, another 10 compounds from CAS COVID-19 antiviral candidate compounds dataset are also suggested by Molecular Complex Characterizing System with potential treatment for COVID-19. Our work provides a novel strategy for the repurposing and combinations of drugs in the market and for prediction of chemical candidates with anti-COVID-19 potential.

Data Evaluation for Cassiterite and Coltan Fingerprinting

Within due diligence concepts for raw material supply chains, the traceability of a shipment is a major aspect that has to be taken into account. Cassiterite and coltan are two so-called conflict minerals for which traceability systems have been established. To provide additional credibility to document-based traceability systems the German Federal Institute for Geosciences and Natural Resources (BGR) has developed the analytical fingerprint (AFP) for the minerals coltan, cassiterite, and wolframite. AFP is based on the analysis of a sample from a shipment with a declared origin and evaluates whether the declared origin is plausible or not. This is done by comparison to reference samples previously taken at the declared mine site. In addition to the generation of the analytical data, the data evaluation step, with the aim to state whether the declared origin is plausible or not, is of special importance. Two data evaluation approaches named “Kolmogorov–Smirnov distance (KS-D) approach” and “areas ratio approach” are applied to coltan and cassiterite and result in very low rates of false negative results, which is desired for AFP. The areas ratio approach based on hypothesis testing and a more sophisticated evaluation of the multivariate data structure has some advantages in terms of producing lower rates of false positive results compared to the KS-D approach.

Are biopsies always necessary in upper and lower gastrointestinal endoscopy in children? A retrospective 10-year analysis.

Little attention has been given to the efficiency and validity of performing routine endoscopic biopsies in normal areas in children. This study aimed to investigate the need to perform routine biopsies in upper gastrointestinal endoscopy (UDE) and colonoscopy in normal areas by comparing macroscopy and histology. It was a 10-year retrospective analysis with the inclusion of 761 UDEs and 177 colonoscopies. Considering all segments, UDEs showed false-positive result rates of 73.11% and false-negative result rates of 14.34%. The histological results modified the initial management in 53.95% of patients. Considering all segments, colonoscopies showed false-positive result rates of 63.64% and false-negative result rates of 30.97%. The histological results modified the initial management in 34.45% of patients.Conclusion: If biopsies were obtained only in abnormal areas, the diagnosis would be lost in 53.95% of the patients in upper endoscopies and 85.7% of the colonoscopies, which justifies routine maintenance of biopsies in macroscopically normal areas in children. What is Known: • Little attention has been given to the efficiency and validity of endoscopic biopsies of normal areas during pediatric exams. • Only a few pediatric studies have correlated macroscopic and histological findings from endoscopic biopsies, and low sensitivity and specificity, as well as poor agreement, were reported. What is New: • Our study confirms the evidence that routine biopsies from macroscopically normal areas during upper and lower digestive endoscopies can lead to histopathological diagnoses and different medical management. • This is the first research on this topic in a Latin population, from a developing country, reassuring the results obtained in previous papers from other countries.

Broken Effects? How to Reduce False Positives in Panel Regressions

Monte Carlo simulations in this paper indicate that often-used regression estimators can easily lead to spurious results. Examples are random effects (RE), logit, and Poisson regressions. These methods were designed for statistical efficiency, but the simulations here demonstrate that they can lead to elevated rates of false positive results in practically plausible situations. More than half of panel regressions in recent SMJ papers still employ estimators that can yield too many false positives. The results of this study suggest that researchers should prioritize conservative estimators over efficient ones, for instance by using clustered standard errors, fixed effects (instead of RE), and linear regressions (instead of, for instance, logit or Poisson).