Test Performance Characteristics Research Articles

Evaluating the performance characteristics of five lateral flow assays for the detection of the SARS-CoV-2 nucleocapsid antigen

In response to the COVID-19 pandemic, lateral flow assays (LFAs) for the detection of SARS-CoV-2 antigen have been proposed as a complementary option to the more costly and time consuming reverse-transcriptase polymerase chain reaction (RT-PCR). We assessed five commercially available SARS-CoV-2 antigen detecting LFAs (ASSUT EUROPE (Rome, Italy), Besthree (Taizhou, China), Encode (Zhuhai, China), Fortress (Antrim UK), and Hughes Medical (Buckinghamshire, UK), using samples collected from hospitalised individuals with COVID-19 and compared these results against established RT-PCR assays with the aim of estimating test performance characteristics. We performed a diagnostic accuracy study of the five LFAs on 110 inpatients with confirmed COVID-19 and 75 COVID-19 negative control participants. Assay evaluation was performed using a modified version of each manufacturer’s protocol allowing for parallel testing of a single sample on multiple assays. Additional variables were studied including infection acquisition, oxygenation requirements at time of swabbing, and patient outcomes. The 110 patients were 48% (53) female, with mean age 67 years (range 26–100 years), and 77% (85) cases were community onset SARS-CoV-2. Across the five assays, sensitivity ranged from 64 (95% CI 53–73) to 76% (95% CI 65–85); Fortress performed best with sensitivity of 76% (95% CI 65–85). Specificity was high across all assays with 4/5 LFAs achieving 100%. LFA sensitivity was not dependant on RT-PCR cycle thresholds. SARS-CoV-2 antigen detecting LFAs may complement RT-PCR testing to facilitate early diagnosis and provide community testing strategies for identification of patients with COVID-19, however we find suboptimal test performance characteristics across a range of commercially available manufacturers, below WHO and MHRA pre-set sensitivity performance thresholds. With such variation in sensitivity between LFAs and PCR testing and between assay brands, we advise caution in the deployment of LFAs outside of environments with clinical oversight.

The clinical and laboratory diagnosis of vaccine-induced immune thrombotic thrombocytopenia

AbstractVaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but serious adverse syndrome occurring 5 to 30 days after adenoviral vector COVID-19 vaccination. Therefore, a practical evaluation of clinical assessments and laboratory testing for VITT is needed to prevent significant adverse outcomes as the global use of adenoviral vector vaccines continues. We received the clinical information and blood samples of 156 patients in Canada with a suspected diagnosis of VITT between April and July 2021. The performance characteristics of various diagnostic laboratory tests were evaluated against the platelet factor 4 (PF4)-14C-serotonin release assay (SRA) including a commercial anti-PF4/heparin immunoglobulin G (IgG)/IgA/IgM enzyme immunoassay (EIA, PF4 Enhanced; Immucor), in-house IgG-specific anti-PF4 and anti-PF4/heparin-EIAs, the standard SRA, and the PF4/heparin-SRA. Of those, 43 (27.6%) had serologically confirmed VITT-positive based on a positive PF4-SRA result and 113 (72.4%) were VITT-negative. The commercial anti-PF4/heparin EIA, the in-house anti-PF4-EIA, and anti-PF4/heparin-EIA were positive for all 43 VITT-confirmed samples (100% sensitivity) with a few false-positive results (mean specificity, 95.6%). These immunoassays had specificities of 95.6% (95% confidence interval [CI], 90.0-98.6), 96.5% (95% CI, 91.2-99.0), and 97.4% (95% CI, 92.4-99.5), respectively. Functional tests, including the standard SRA and PF4/heparin-SRA, had high specificities (100%), but poor sensitivities for VITT (16.7% [95% CI, 7.0-31.4]; and 46.2% [95% CI, 26.6-66.6], respectively). These findings suggest EIA assays that can directly detect antibodies to PF4 or PF4/heparin have excellent performance characteristics and may be useful as a diagnostic test if the F4-SRA is unavailable.

PM 7/40 (5) Globodera rostochiensis and Globodera pallida

PM 7/40 (5) <i>Globodera rostochiensis</i> and <i>Globodera pallida</i>

Optimization and Validation of Nanopore Based Sequencing Method for Molecular Testing of CNS Tumours

BackgroundThe World Health Organization (WHO) introduced molecular identifiers for the diagnosis and prognosis of CNS tumors including the mutational status of isocitrate dehydrogenase or IDHgenes in glial tumors. Currently used immunohistochemistry (IHC) is not capable of detecting the non‐canonical mutations, and sequencing is often required as a follow‐up. Current next‐generation sequencing (NGS) technologies used in tumor molecular marker detection introduce key challenges including high capital cost, complex infrastructure requirements, and long turnaround times. These challenges considerably limit the ability to perform NGS testing in many pathology laboratories. In this study, we aimed to use third generation nanopore sequencing technology to resolve these limitations. The Oxford Nanopore MinION, a pocket‐sized nanopore sequencing device, has minimal capital costs and infrastructural requirements, and shorter turnaround times. However, the nanopore technology has not been validated in clinical practice and has not been optimized on formalin‐fixed paraffin‐embedded (FFPE) tissue.MethodsDNA extraction of selective tumor areas was performed from the corresponding FFPE tissue blocks from a cohort of gliomas with confirmed IDH1and IDH2gene statuses (n=65). A PCR amplicon‐based approach was used to amplify hot spots of the IDH1and IDH2genes, starting with 30ng DNA material. The amplicon libraries were sequenced for 2 hours in multiplex on the MinION device and IDHSNPs were called with the Nanopolish software. ASIP Abstract Mashiat MimosaResults26 IDH mutant samples were identified: 21 IDH1R132H, 2 IDH1R132G, 2 IDH2R172G, and 1 IDH2D177H. All cases showed concordant IDHmutational status when compared to the reference methods (IHC or NGS) and both analytical sensitivity and specificity were 100%. Precision analysis of variant allele frequency (VAF) showed the coefficient of variation was less than 5% (both inter and intra runs), and the limit of detection for VAF was 3%. The range of read depth obtained was 882X to 43,000x with an average of 20,000x. This assay revealed a $50‐$100 material cost per sample, and the time taken from extracted nucleic acid to final result generation was 1‐2 business days.ConclusionThis project is the first to optimize and validate an approach to detect SNP mutations in FFPE samples using nanopore technology. It has demonstrated the feasibility and efficacy of the nanopore amplicon sequencing method in cancer FFPE tissue with excellent test performance characteristics, significantly shorter turnaround times at considerably lower costs and without any infrastructural needs. Thus, it can be used to circumvent challenges to current NGS testing platforms and can be the milestone that would make cancer NGS testing available for every laboratory.

Two-test algorithms for infectious disease diagnosis: Implications for COVID-19.

Diagnostic assays for various infectious diseases, including COVID-19, have been challenged for their utility as standalone point-of-care diagnostic tests due to suboptimal accuracy, complexity, high cost or long turnaround times for results. It is therefore critical to optimise their use to meet the needs of users. We used a simulation approach to estimate diagnostic outcomes, number of tests required and average turnaround time of using two-test algorithms compared with singular testing; the two tests were reverse transcription polymerase chain reaction (RT-PCR) and an antigen-based rapid diagnostic test (Ag-RDT). A web-based application of the model was developed to visualise and compare diagnostic outcomes for different disease prevalence and test performance characteristics (sensitivity and specificity). We tested the model using hypothetical prevalence data for COVID-19, representing low- and high-prevalence contexts and performance characteristics of RT-PCR and Ag-RDTs. The two-test algorithm when RT-PCR was applied to samples negative by Ag-RDT predicted gains in sensitivity of 27% and 7%, respectively, compared with Ag-RDT and RT-PCR alone. Similarly, when RT-PCR was applied to samples positive by Ag-RDT, specificity gains of 2.9% and 1.9%, respectively, were predicted. The algorithm using Ag-RDT followed by RT-PCR as a confirmatory test for positive patients limited the requirement of RT-PCR testing resources to 16,400 and 3,034 tests when testing a population of 100,000 with an infection prevalence of 20% and 0.05%, respectively. A two-test algorithm comprising a rapid screening test followed by confirmatory laboratory testing can reduce false positive rate, produce rapid results and conserve laboratory resources, but can lead to large number of missed cases in high prevalence setting. The web application of the model can identify the best testing strategies, tailored to specific use cases and we also present some examples how it was used as part of the Access to Covid-19 Tools (ACT) Accelerator Diagnostics Pillar.

Multi-target blood test to improve the performance of hepatocellular carcinoma surveillance programs: A modeling-based virtual trial.

405 Background: Hepatocellular carcinoma (HCC) is the fastest rising cause of cancer mortality in the United States. Although clinical guidelines recommend ultrasound (U/S), with or without the serum biomarker alpha fetoprotein (AFP) for HCC surveillance in at-risk patients, only 24% of patients adhere to surveillance and only one-third of HCCs are detected before developing symptoms. A multi-target HCC blood-based test (mt-HBT) was recently shown to have promising sensitivity for early HCC detection and may help improve surveillance adherence given its blood-based nature. Our objective was to evaluate the comparative clinical effectiveness of mt-HBT with the current standard-of-care surveillance strategy in patients with cirrhosis. Methods: We simulated a virtual trial by developing a microsimulation model of the natural history of HCC in patients with compensated (Child Pugh A) cirrhosis over a 30-year horizon. To inform model parameters, we used published data on tumor progression, competing risks of mortality, and real-world HCC surveillance adherence. Test performance characteristics were informed by a network meta-analysis. We simulated the life course of 51-year-old patients with cirrhosis and compared no surveillance with biannual surveillance using (1) AFP only, (2) U/S only, (3) U/S+AFP, (4) mt-HBT, and (5) mt-HBT with improved adherence. We assumed a blood-based test—without U/S—would improve surveillance adherence by 10% compared with current adherence (̃4% absolute improvement). Results: Per 100,000 cirrhosis patients, mt-HBT detected 6,220 more early-stage HCC than no surveillance, 2,250 (+57%) more than AFP, 1080 (+21%) more than U/S, and 200 (-3%) less than U/S+AFP. mt-HBT with improved adherence detected 210 (+3%) more early-stage HCC than U/S+AFP (Table). The remaining HCC cases were either symptomatic or the patients died per other competing causes prior to detection. The number of screening tests needed to detect one HCC were 296 for AFP, 287 for U/S, 253 for U/S+AFP, 254 for mt-HBT and 262 for mt-HBT with improved adherence. The number of diagnostic MRI/CT needed to detect one HCC were 40 for AFP, 38 for U/S, 45 for U/S+AFP, 37 for mt-HBT, and 38 for mt-HBT with improved adherence. Conclusions: mt-HBT detects more early-HCC cases than U/S and similar number of early-HCC cases with U/S+AFP. By decreasing surveillance barriers and increasing adherence, mt-HBT could improve early HCC detection and could be promising option for HCC surveillance in patients with cirrhosis. [Table: see text]

Measurable Residual Disease Assessment as a Surrogate Marker in New Drug Development in Acute Myeloid Leukemia.

Response criteria for patients treated for acute myeloid leukemia (AML) based on cytomorphology are inadequate. Many patients achieving a complete remission by such criteria will later relapse. Patients with AML in such remissions who test negative using higher sensitivity measures of residual disease burden (measurable residual disease [MRD]) have on average lower relapse rates and better survival than those testing positive. This association has raised the possibility that these technological advances in measurement of tumor burden could be used to optimize the drug development and regulatory approval processes in AML. The heterogeneous genetic etiology, diverse immunophenotypic profiles, related precursor states and polyclonal architecture however combine to make the development of standardized and validated MRD assessments for AML challenging. Current and future methods to measure residual disease in AML, performance characteristics of testing currently in use, and potential uses for optimized AML MRD tests including as a surrogate endpoint are discussed.

Point-of-Care Ultrasonography for Ankle Injuries in Children.

The aim of the study was to determine whether point-of-care ultrasound (US) can decrease x-rays in children with ankle injuries. Secondary objectives were to determine the test performance characteristics for ankle US, analyze diagnostic errors, and compare US with the Ottawa Ankle Rules (OAR). This was a prospective study of children younger than 21 years presenting to an emergency department with an ankle injury requiring x-rays. Pediatric emergency medicine physicians received a 1-hour training session, performed ankle US with a standardized scanning protocol of the distal tibia and fibula, and described the US as positive, negative, or equivocal for fracture. Ankle x-ray interpretation by a radiologist was the reference standard for fracture. One hundred twenty patients with a mean age of 13.5 (±4.0) years were enrolled. Nine patients (7.5%) had an ankle fracture on x-ray, and 56 patients (47%) had open physes. Ankle US would reduce x-rays by 81 (67.5%), missing 2 intra-articular, nondisplaced, tibial fractures in patients with open physes. Ankle US had a sensitivity of 78% (95% confidence interval [CI], 40%-97%), specificity of 71% (95% CI, 62%-79%), likelihood ratio for a positive test of 2.7 (95% CI, 1.7-4.3), and likelihood ratio for a negative test of 0.31 (95% CI, 0.09-1.07). The OAR would reduce x-rays by 21 (17.5%), missing one fracture. Ultrasound with OAR would reduce x-rays by 20 (17%) with no missed fractures. Point-of-care US has the potential to reduce x-rays for children with ankle injuries; however, nondisplaced, intra-articular tibial fractures may be missed. Ultrasound with OAR may reduce radiographs without missed fractures in this population.

SARS-CoV-2 and Variant Diagnostic Testing Approaches in the United States.

Purpose of Review Given the rapid development of diagnostic approaches to test for and diagnose infection with SARS-CoV-2 and its associated variants including Omicron (B.1.1.529), many options are available to diagnose infection. Multiple established diagnostic companies are now providing testing platforms whereas initially, testing was being performed with simple PCR-based tests using standard laboratory reagents. Recent Findings Additional testing platforms continue to be developed, including those to detect specific variants, but challenges with testing, including obtaining testing reagents and other related supplies, are frequently encountered. With time, the testing supply chain has improved, and more established companies are providing materials to support these testing efforts. In the United States (U.S.), the need for rapid assay development and subsequent approval through the attainment of emergency use authorization (EUA) has superseded the traditional arduous diagnostic testing approval workflow mandated by the FDA. Through these efforts, the U.S. has been able to continue to significantly increase its testing capabilities to address this pandemic; however, challenges still remain due to the diversity of the performance characteristics of tests being utilized and newly discovered viral variants. Summary This review provides an overview of the current diagnostic testing landscape, with pertinent information related to SARS-CoV-2 virology, variants and antibody responses that are available to diagnose infection in the U.S.

Evaluation of Abbott ID NOW COVID-19 POC test performance characteristics and integration in the regional health network workflows to improve health care delivery

With the recent global surge of SARS-CoV-2 Delta variant, there continues to be high demand for COVID-19 diagnostic testing. Abbott ID NOW is a rapid, CLIA-waived, COVID-19 diagnostic test ideally suited for use in urgent care settings or where access to diagnostic testing is limited. In this study we describe the results of rigorous validation of ID NOW and post-implementation study of POC test utilization patterns within community hospitals and clinics. Performance of ID NOW was validated by comparison of the results from 207 consecutive, paired, specimens tested on the ID NOW and on the m2000/Alinity m platforms. Once validated, ID NOW devices were placed for clinical use at four regional hospitals and clinics.We found that the ID NOW and m2000/Alinity m positive and negative percent agreement were 94.5% (95% CI, 85.1% to 98.1%) and 99.3% (95% CI, 96.4% to 99.9%), respectively. As of August 2021, a total of 2,301 tests were performed by ID NOW at individual regional network sites. The population tested consisted of 55.5% White and 42.9% Black patients, with Black patients presenting predominantly in the hospitals, while White patients were more evenly distributed between hospital and clinic sites. Disease prevalence observed among patients tested by ID NOW (12.3%) was aligned with overall prevalence seen at regional sites (11.3%).In summary, the ID NOW test can provide rapid and accurate results in a variety of near-to-patient and POC settings. If used correctly, it could serve as a valuable diagnostic tool to enable equal access to care and improve healthcare delivery within large health network systems.

Pediatric Clostridioides difficile Infection: Diagnosis and Diagnostic Stewardship.

Although the pathogenesis of Clostridioides difficile infection (CDI) is complex and incompletely understood, it is believed that the elaboration of C. difficile toxins is necessary for disease. There are a variety of tests available for the detection of both the C. difficile organism and its toxins; however, each has limitations and the best application of these tests to the diagnosis of CDI in children remains uncertain. Nucleic acid amplification tests are unable to reliably discriminate between CDI and C. difficile colonization, while commercially available enzyme immunoassays for toxin detection lack sensitivity. An understanding of preanalytic factors, relevant patient features, and test performance characteristics is essential to the accurate diagnosis of CDI in children. Specific diagnostic stewardship strategies can also increase the likelihood that positive tests reflect disease rather than colonization. Ultimately, CDI remains a clinical diagnosis and clinical judgment is essential when interpreting test results, regardless of the methods used.

Rapid Review: Diagnostic Accuracy of Pooled Testing versus Individual Testing Using RT-PCR for SARS-CoV-2 for Screening and Surveillance of Individuals with Suspected COVID-19

Background. Pooled testing has been implemented on a limited scale, mainly for screening and surveillance in populations with a low prevalence of COVID-19 to save on limited resources.&#x0D; Objective. To determine the diagnostic accuracy of pooled compared with individual RT-PCR testing for SARS-CoV-2 in individuals suspected of COVID-19.&#x0D; Methods. We searched websites of living CPGs on COVID-19 (Australian COVID-19, COVID NMA, CEBM Oxford), Philippine DOH HTA, databases (PubMed, CENTRAL, medRXIV/bioRXIV), and Clinicaltrials.gov for studies that used pooled testing on individuals suspected of COVID-19. When appropriate, we pooled data for sensitivity and specificity and obtained the range and median of other data, such as positive predictive value and resource savings. We did a priori subgroup analysis for pool size, presence or absence of symptoms and use case, type of specimen, cutoff for positivity, type of kit, and post hoc subgroup analysis for method of pooling and timing of processing.&#x0D; Results. We included 21 studies: 6 diagnostic accuracy studies, and 15 clinical validation studies. Studies had varying populations, index test kit and performance characteristics, positivity rate (0.02 to 15%), and pool size (5 to 16). There was moderate pooled sensitivity, 81% (95% CI 72, 88; I2=73.6%; 6 studies, 776 pools) and high pooled specificity, 99% (95% CI, 98 to 100; I2=1.84%; 5 studies, 666 pools). Positive predictive value based on 21 studies ranged from 67% to 100%. Resource savings in the number of test kits used ranged from 49 to 89%. Identified harms of pooled testing were delayed turnaround time for positive samples and laboratory errors.&#x0D; Conclusion. There is moderate sensitivity and high specificity with pooled testing for the screening of individuals with suspected COVID-19. We recommend further studies to validate the utility based on community prevalence and other test variables.

Performance characteristics of chimerism testing by next generation sequencing

Chimerism testing provides informative clinical data regarding the status of a biological sample mixture. For years, this testing was achieved by measuring the peaks of informative short tandem repeat (STR) loci using capillary electrophoresis (CE). With the advent of next generation sequencing (NGS) technology, the quantification of the percentage of donor/recipient mixtures is more easily done using sequence reads in large batches of samples run on a single flow cell. In this study, we present data on using a FORENSIC NGS chimerism platform to accurately measure the percentage of donor/recipient mixtures. We were able to detect chimerism to a limit threshold of 1% using both STR and single nucleotide polymorphism (SNP) informative loci. Importantly, a significant correlation was observed between NGS and CE chimerism methods when compared at donor detection ranges from 1% to 10%. Furthermore, 100% accuracy was achieved through proficiency testing over six surveys. Its usefulness was expanded beyond this to help identify suitable donors for solid organ transplant patients using ancestry SNP profiles. In summary, the NGS method provides a sensitive and reliable alternative to traditional CE for chimerism testing of clinical samples.

Implementing lateral flow devices in long-term care facilities: experiences from the Liverpool COVID-19 community testing pilot in care homes\u2014 a qualitative study

IntroductionAntigen-based lateral flow devices (LFDs) offer the potential of widespread rapid testing. The scientific literature has primarily focused on mathematical modelling of their use and test performance characteristics. For these tests to be implemented successfully, an understanding of the real-world contextual factors that allow them to be integrated into the workplace is vital. To address this gap in knowledge, we aimed to explore staff’s experiences of integrating LFDs into routine practice for visitors and staff testing with a view to understand implementation facilitators and barriers.MethodsSemi-structured interviews and thematic analysis.ResultsWe identified two main themes and five subthemes. The main themes included: visitor-related testing factors and staff-related testing factors. Subthemes included: restoring a sense of normality, visitor-related testing challenges, staff-related testing challenges, and pre-pilot antecedent factors.ConclusionOur study demonstrates that the real-world implementation of LFDs to test visitors and staff faces significant challenges as a result of several contextual factors negatively affecting the work practice and environment. More comprehensive studies are needed to identify and inform effective implementation strategies to ensure that LFDs can be adopted in an agile way that better supports an already exhausted and morally depleted workforce.

Clinical and Molecular facets of Dengue Virus infection from Bengaluru, South India.

BackgroundDengue virus (DENV) continues to be an epidemic with high mortality rates. The clinical features, especially in the early phase of infection, are nonspecific and there is no single marker that can be reliably deployed for diagnostics. Further, serotype and genotype diversity is not clearly understood. This study was conceived to understand the performance characteristics of various diagnostic markers; serotype and genotype distribution is thus a vital requirement.MethodsA subset of blood samples was obtained for all the clinically suspected Dengue cases during the period January to December 2017. The samples were tested for IgM and IgG antibodies and NS1 antigen by both ELISA and rapid tests. Real-time PCR, Conventional PCR and sequencing was performed based on the serology results. Correlation of the data with demographic and clinical details was used to analyze the performance characteristics of various tests.ResultsClinical signs and symptoms could not predict dengue positivity due to lack of specific symptoms. The performance of IgM rapid test was found to be lower than the ELISA method (53.5% agreement). The NS1 rapid and NS1 ELISA tests were comparable (89.2% agreement). Majority of the infections were caused due to DEN-2 serotype and phylogenetic analysis revealed all the sequenced DEN-2 serotypes belong to Genotype IV. Three sequences were deposited into NCBI GenBank (GenBank accession number MW583116, MW579054 and MW579053).ConclusionOur comprehensive data suggests that NS1 ELISA and PCR are best used in the early phase of dengue infection (< 5 days post-onset of fever), whereas IgM antibody detection is reliable only in the late phase. We also highlight the unreliable performance of rapid tests.

Precision of Serologic Testing from Dried Blood Spots Using a Multiplex Bead Assay.

Multiplex bead assays (MBAs) for serologic testing have become more prevalent in public health surveys, but few studies have assessed their test performance. As part of a trachoma study conducted in a rural part of Ethiopia in 2016, dried blood spots (DBS) were collected from a random sample of 393 children aged 0 to 9 years, with at least two separate 6-mm DBS collected on a filter card. Samples eluted from DBS were processed using an MBA on the Luminex platform for antibodies against 13 antigens of nine infectious organisms: Chlamydia trachomatis, Vibrio cholera, enterotoxigenic Escherichia coli, Cryptosporidium parvum, Entamoeba histolytica, Camplyobacter jejuni, Salmonella typhimurium Group B, Salmonella enteritidis Group D, and Giardia lamblia. Two separate DBS from each child were processed. The first DBS was run a single time, with the MBA set to read 100 beads per well. The second DBS was run twice, first at 100 beads per well and then at 50 beads per well. Results were expressed as the median fluorescence intensity minus background (MFI-BG), and classified as seropositive or seronegative according to external standards. Agreement between the three runs was high, with intraclass correlation coefficients of > 0.85 for the two Salmonella antibody responses and > 0.95 for the other 11 antibody responses. Agreement was also high for the dichotomous seropositivity indicators, with Cohen's kappa statistics exceeding 0.87 for each antibody assay. These results suggest that serologic testing on the Luminex platform had strong test performance characteristics for analyzing antibodies using DBS.

Screening for anxiety disorders in third trimester pregnancy: a comparison of four brief measures.

Evidence regarding the accuracy of existing anxiety screeners used in pregnancy is limited. This study compares the psychometric characteristics of the Generalized Anxiety Disorder 2- and 7-item Scales (GAD-2 and GAD-7), the anxiety subscale of the Edinburgh Postnatal Depression Scale (EPDS-3A) and the two anxiety items of the Antenatal Risk Questionnaire (ANRQ-2A). Nine hundred fifty-four women completed the screening measures and anxiety modules of a diagnostic reference standard (SAGE-SR) in the third trimester. Test performance characteristics of each measure was assessed using Receiver Operator Characteristic (ROC) analysis. We applied four previously recommended criteria to ascertain the value of each measure for widespread clinical use: area under the curve (AUC ≥ 0.8, Youden's index ≥ 0.5, negative predictive value (NPV) ≥ 0.8 and positive likelihood ratio (LR +) ≥ 4.0). Prevalence for any SAGE-SR anxiety disorder was 3%. All measures yielded an acceptable AUC of ≥ 0.8, Youden's index of ≥ 0.5 and NPV of ≥ 0.8. Only the EPDS-3A, at a cut-point ≥ 5, also achieved a LR + of ≥ 4.0 (4.35) but at this cut-point sensitivity was less than 0.75. The ANRQ-2A, at its optimal cut-point of ≥ 6, was the only measure to additionally attain both a sensitivity and specificity of ≥ .75. This study expands the evidence base for brief anxiety screening measures in the maternity setting and provides empirical support for the use of the EPDS-3A and ANRQ-2A in routine screening programmes. Studies assessing the performance of these measures in samples with higher disease prevalence and broader socio-economic status are warranted.

PPV and Detection Rate of mt-sDNA Testing, FIT, and CT Colonography for Advanced Neoplasia: A Hierarchic Bayesian Meta-Analysis of the Noninvasive Colorectal Screening Tests.

BACKGROUND. Noninvasive tests for colorectal cancer (CRC) screening and prevention limit the need for invasive colonoscopy to follow up positive test results. However, the relative performance characteristics of available noninvasive tests have not yet been adequately compared. OBJECTIVE. We performed a systematic review and meta-analysis to compare the diagnostic performance of the available noninvasive CRC screening tests, including multitarget stool DNA (mt-sDNA) testing, fecal immunochemical testing (FIT), and CT colonography (CTC), with an emphasis on comparison of PPV and detection rate (DR) for advanced neoplasia (AN; encompassing cases of advanced adenomas and CRC). EVIDENCE ACQUISITION. After systematic searches of MEDLINE and Google Scholar databases, 10 mt-sDNA, 27 CTC, and 88 FIT published screening studies involving 25,132, 33,493, and 2,355,958 asymptomatic adults, respectively, were included. Meta-analysis with hierarchic Bayesian modeling was conducted in accordance with Cochrane Collaboration and PRISMA guidelines to determine test positivity rates (TPRs) leading to optical colonoscopy, as well as PPVs and DRs for both AN and CRC. Different positivity thresholds were considered for FIT and CTC. EVIDENCE SYNTHESIS. Point estimates (with 95% credible intervals) from pooled Bayesian meta-analysis combining all thresholds for FIT and stratifying CTC results by a polyp size threshold of 6 mm or larger (CTC6) and 10 mm or larger (CTC10) were calculated. TPR was 13.5% (10.9-16.6%) for mt-sDNA testing, 6.4% (5.8-7.2%) for FIT, 13.4% (11.4-15.6%) for CTC6, and 6.6% (5.2-7.7%) for CTC10. AN PPV was 26.9% (95% credible interval, 21.8-33.2%) for mt-sDNA testing, 31.8% (29.3-34.5%) for FIT, 34.4% (27.2-41.0%) for CTC6, and 61.0% (54.0-70.0%) for CTC10. CRC PPV was 2.4% (1.5-3.9%) for mt-sDNA testing, 4.9% (4.3-5.3%) for FIT, 3.5% (2.5-4.8%) for CTC6, and 6.0% (4.3-8.0%) for CTC10. The DR for AN was 3.4% (95% credible interval, 2.5-4.8%) for mt-SDNA, 2.0% (1.8-2.3%) for FIT, 4.8% (4.0-6.5%) for CTC6, and 4.0% (3.0-4.6%) for CTC10. When FIT is restricted to a lower threshold (< 10 μg Hb/g feces), its performance profile is similar to that of mt-sDNA testing, although available data are limited. AN PPV odds ratios (relative to CTC10 as the reference) were 0.24 (95% credible interval, 0.17-0.33) for mt-sDNA testing, 0.30 (0.24-0.45) for FIT, and 0.33 (0.25-0.47) for CTC6. CONCLUSION. Among noninvasive CRC screening tests, CTC with a polyp size threshold of 10 mm or larger most effectively targets AN, preserving detection while also decreasing unnecessary colonoscopies compared with mt-sDNA testing and FIT. CLINICAL IMPACT. CTC performed with a polyp size threshold for colonoscopy referral set at 10 mm or larger represents the most effective and efficient noninvasive screening test for CRC prevention and detection.

Evaluation of 20 clinical chemistry and 12 immunoassay analytes in terms of total analytical error and measurement uncertainty

In analytical quality management, target setting models that are selected by the purpose together with the error models that are applied correctly have critical importance. In our study, we aimed to compare the analytical performance characteristics of routine clinical chemistry and immunoassay tests with different target-setting models proposed by various organizations. Our study was performed with internal and external quality control data obtained using Beckman Coulter AU680 for clinical chemistry analytes and Roche Cobas 8000 autoanalyzer for immunoassay analytes. The total analytical error (TAE) was calculated by the formula TAH%=1.65×(CV%)+Bias%. Measurement uncertainty (MU) has been calculated adhering to the Nordtest guideline. Results were compared with BVEFLM, CLIA, RCPA, PRDEQA%, pUEQAS%, and permissible MU (pU%) data to investigate analytical performance qualities. When we compare the results of TAE and MU, MU was found to be higher than TAE for all analytes. ALT, AST, glucose, K, and triglycerides met all target values, showing the best performance. Taken together, our results show that CLIA for total analytical error and PRDEQA% and pUEQAS% for measurement uncertainty can match better than BVEFLM, RCPA and pU%. These test results should be evaluated with measurement uncertainty to avoid misdiagnosis. Appropriate specification limits should be defined for the examination of test methods that meet the objectives for fitness for clinical purposes.

The PATHFINDER Study: Assessment of the Implementation of an Investigational Multi-Cancer Early Detection Test into Clinical Practice.

Simple SummaryPATHFINDER is an interventional study that will examine how well a multi-cancer early detection test can be integrated into clinical practice. This test looks at DNA methylation patterns in patient blood samples to detect cancer and also predict cancer origin. The PATHFINDER study will include ~6200 study participants from 31 sites in the United States. The study will return tests results to participants and their health care providers and will evaluate how test results affect the clinical pathway to confirm or rule out a cancer diagnosis. Results of this study could help determine how a blood-based multi-cancer early detection test will fit into clinical practice.To examine the extent of the evaluation required to achieve diagnostic resolution and the test performance characteristics of a targeted methylation cell-free DNA (cfDNA)-based multi-cancer early detection (MCED) test, ~6200 participants ≥50 years with (cohort A) or without (cohort B) ≥1 of 3 additional specific cancer risk factors will be enrolled in PATHFINDER (NCT04241796), a prospective, longitudinal, interventional, multi-center study. Plasma cfDNA from blood samples will be analyzed to detect abnormally methylated DNA associated with cancer (i.e., cancer “signal”) and a cancer signal origin (i.e., tissue of origin). Participants with a “signal detected” will undergo further diagnostic evaluation per guiding physician discretion; those with a “signal not detected” will be advised to continue guideline-recommended screening. The primary objective will be to assess the number and types of subsequent diagnostic tests needed for diagnostic resolution. Based on microsimulations (using estimates of cancer incidence and dwell times) of the typical risk profiles of anticipated participants, the median (95% CI) number of participants with a “signal detected” result is expected to be 106 (87–128). Subsequent diagnostic evaluation is expected to detect 52 (39–67) cancers. The positive predictive value of the MCED test is expected to be 49% (39–58%). PATHFINDER will evaluate the integration of a cfDNA-based MCED test into existing clinical cancer diagnostic pathways. The study design of PATHFINDER is described here.