Point-of-care Assay Research Articles

Globally Rare BRCA2 Variants With Founder Haplotypes in the South African Population: Implications for Point-of-Care Testing Based on a Single-Institution BRCA1/2 Next-Generation Sequencing Study.

Breast cancer patients historically benefitted from population-based genetic research performed in South Africa, which led to the development of founder-based BRCA1/2 diagnostic tests. With the advent of next-generation sequencing (NGS) technologies, the clinical utility of limited, targeted genetic assays were questioned. The study focused on mining NGS data obtained from an extensive single-institution NGS series (n=763). The aims were to determine (i) the prevalence of the most common recurrent/founder variants in patients referred for NGS directly; and (ii) to explore the data for inferred haplotypes associated with previous and potential new recurrent/founder variants. The identification of additional founder variants was essential for promoting and potentially advancing to rapid founder-based BRCA1/2 point-of-care (POC) technology as a time- and cost-effective alternative. NGS revealed actionable BRCA1/2 variants in 11.1% of patients tested (BRCA1 – 4.7%; BRCA2 – 6.4%), of which 22.4% represented variants currently screened for using first-tier targeted genetic testing. A retrospective investigation into the overall mutation-positive rate for an extended cohort (n=1906), which included first-tier test results, revealed that targeted genetic testing identified 74% of all pathogenic variants. This percentage justified the use of targeted genetic testing as a first-tier assay. Inferred haplotype analysis confirmed the founder status of BRCA2 c.5771_5774del (rs80359535) and c.7934del (rs80359688) and revealed an additional African founder variant (BRCA2 c.582G>A – rs80358810). A risk-benefit analysis using a questionnaire-based survey was performed in parallel to determine genetic professionals’ views regarding POC testing. This was done to bridge the clinical implementation gap between haplotype analysis and POC testing as a first-tier screen during risk stratification of breast and ovarian cancer patients. The results reflected high acceptance (94%) of BRCA1/2 POC testing when accompanied by genetic counselling. Establishing the founder status for several recurrent BRCA2 variants across ethnic groups supports unselected use of the BRCA POC assay in all SA breast/ovarian cancer patients by recent local and international public health recommendations. Incorporating POC genotyping into the planned NGS screening algorithm of the Department of Health will ensure optimal use of the country’s recourses to adhere to the set standards for optimal care and management for all breast cancer patients.

Comparison of serum and plasma SDMA measured with point-of-care and reference laboratory analysers: implications for interpretation of SDMA in cats.

Symmetric dimethylarginine (SDMA) reflects the glomerular filtration rate (GFR) in people, dogs and cats. Initial assays used a liquid chromatography-mass spectroscopy (LC-MS) technique. A veterinary immunoassay has been developed for use in commercial laboratories and point-of-care (POC) laboratory equipment. This study sought to: determine POC and commercial laboratory (CL) SDMA assay imprecision; determine any bias of the POC assay compared with the CL assay; calculate observed total error of the POC assay and compare with analytical performance goals; and calculate dispersion and sigma metrics (σ) for POC and CL SDMA methods. Two separate studies were performed that assessed: (1) imprecision, determined by evaluation of pooled feline plasma or serum; and (2) bias, assessed by comparing pooled plasma and serum results, as well as paired analyses of clinical samples from a single venepuncture measured using both analysers. Results were assessed in relation to performance goals. Dispersion and σ were calculated for both analysers. Bias between CL and POC analysers was consistent and high numbers of clinical results were outside performance goals across both studies. Imprecision was poor for both analysers for study 1 and improved to within quality goals for the CL analyser for study 2. Dispersion was at least 40%, meaning a measured result of 14 μg/dl represents a range of possible results from 8 μg/dl to 20 μg/dl. Clinicians should be careful ascribing medical significance to small changes in SDMA concentration, as these may reflect analytical and biological variability. Analyser-specific reference intervals are likely required.

Performance of a True Point-of-Care Assay for HIV-1/2 Viral Load Measurement at Antenatal and Postpartum Services.

Timely viral load (VL) results during pregnancy and the postpartum period are crucial for HIV disease management and for preventing mother-to-child transmission. Point-of-care (POC) VL testing could reduce turnaround times and streamline patient management. We evaluated the diagnostic performance of the novel m-PIMA HIV-1/2 VL assay (Abbott, Chicago, IL) in Mozambique. The study was conducted in prenatal and postpartum consultation rooms in 2 primary health care clinics. Sample collection and testing on m-PIMA were performed by trained nurses. HIV-infected pregnant and postpartum women on antiretroviral treatment (ART) or ART naive were tested using both on-site m-PIMA POC and referral laboratory-based real-time VL assays. Linear regression analysis and Bland-Altman plots were used to calculate the agreement between both. Correlation between venous blood plasma POC and plasma laboratory-based VL was strong (r2 = 0.850, P < 0.01), with good agreement between the methods [overall bias 0.202 log copies/mL (95% CI: 0.366 to 0.772 log copies/mL)]. Using the threshold of 1000 copies/mL, which is used to determine ART failure, the sensitivity and specificity of the POC VL assay were 95.0% (95% CI: 91.6% to 97.3%) and 96.5% (95% CI: 94.2% to 98.0%), respectively. The correlation coefficient between the venous and capillary sample types was 0.983 (r2 = 0.966). On-site, nurse-performed POC VL testing is feasible and accurate in resource-limited primary health care settings. The operational challenge of plasma separation within clinics for POC testing was successfully overcome using minicentrifuges. The use of capillary blood could simplify the execution of the assay in a clinical environment.

Performance evaluation of Truenat™ Beta CoV & Truenat™ SARS-CoV-2 point-of-care assays for coronavirus disease 2019.

Background & objectives:The rapid diagnosis of coronavirus disease 2019 (COVID-19) is a significant step towards the containment of the virus. The surge of COVID-19 cases in India and across the globe necessitates a rapid and sensitive molecular assay. Rapid point-of-care (PoC) assays (Truenat Beta CoV and Truenat SARS-CoV-2 assays) for the diagnosis of COVID-19 have been developed which are expected to shorten the turnaround time of reporting of results and also can be used for field investigations of COVID-19. The objectives of the study were to validate the performance of Truenat Beta CoV and Truenat SARS-CoV-2 PoC assays for the detection of SARS-CoV-2 infected cases with reference to analytical sensitivity, precision/inter-machine variation, clinical sensitivity and clinical specificity.Methods:The rapid PoC screening and confirmatory assays were prospectively validated at the State Level Virus Research and Diagnostic Laboratory at Bangalore Medical College and Research Institute, Bengaluru, under technical supervision by the Indian Council of Medical Research-National Institute of Virology (ICMR-NIV), Pune. Real-time reverse transcription-polymerase chain reaction (rRT-PCR) was considered as the reference standard against which the rapid assays were validated for all samples tested based on analytical sensitivity, precision/inter-machine variation, clinical sensitivity and clinical specificity.Results:Truenat Beta CoV and Truenat SARS-CoV-2 assays showed concordant results when compared with the reference standard rRT-PCR. These PoC assays exhibited 100 per cent sensitivity, specificity, positive predictive value and negative predictive value.Interpretation & conclusions:Truenat Beta CoV and Truenat SARS-CoV-2 assays showed concordance with the reference standard assay and may be recommended for screening and confirmation of SARS-CoV-2 in the field settings.

Implementation and operational feasibility of SAMBA I HIV-1 semi-quantitative viral load testing at the point-of-care in rural settings in Malawi and Uganda.

We monitored a large-scale implementation of the Simple Amplification-Based Assay semi-quantitative viral load test for HIV-1 version I (SAMBA I Viral Load=SAMBA I VL) within Médecins Sans Frontières' HIV programmes in Malawi and Uganda, to assess its performance and operational feasibility. Descriptive analysis of routine programme data between August 2013 and December 2016. The dataset included samples collected for VL monitoring and tested using SAMBA I VL in five HIV clinics in Malawi (four peripheral health centres and one district hospital), and one HIV clinic in a regional referral hospital in Uganda. SAMBA I VL was used for VL testing in patients who had been receiving ART for between 6months and ten years, to determine whether plasma VL was above or below 1000 copies/mL of HIV-1, reflecting ART failure or efficacy. Randomly selected samples were quantified with commercial VL assays. SAMBA I instruments and test performance, site throughput, and delays in communicating results to clinicians and patients were monitored. Between August 2013 and December 2016 a total of 60889 patient samples were analysed with SAMBA I VL. Overall, 0.23% of initial SAMBA I VL results were invalid; this was reduced to 0.04% after repeating the test once. Global test failure, including instrument failure, was 1.34%. Concordance with reference quantitative testing of VL was 2620/2727, 96.0% (1338/1382, 96.8% in Malawi; 1282/1345, 95.3% in Uganda). For Chiradzulu peripheral health centres and Arua Hospital HIV clinic, where testing was performed on-site, same-day results were communicated to clinicians for between 91% and 97% of samples. Same-day clinical review was obtained for 84.7% across the whole set of samples tested. SAMBA I VL testing is feasible for monitoring cohorts of 1000 to 5000 ART-experienced patients. Same-day results can be used to inform rapid clinical decision-making at rural and remote health facilities, potentially reducing time available for development of resistance and conceivably helping to reduce morbidity and mortality.

Is the Urine Cannabinoid Level Measured via a Commercial Point-of-Care Semiquantitative Immunoassay a Cannabis Withdrawal Syndrome Severity Predictor?

Background: For cannabis-dependent subjects, the relationship between cannabis withdrawal syndrome (CWS) severity and the urine cannabinoid concentrations are unclear; we investigated this using a commercial point-of-care (POC) enzyme immunoassay detecting 11-nor-9-carboxy-Delta-9-tetrahydrocannabinol (THC-COOH).Methods: Observational study of 78 adult chronic cannabis-dependent subjects assessed over a 24-day inpatient detoxification treatment, with 13 serial measurement days. Repeated Measures Correlation and Multilevel Linear Models were employed.Results: Absolute urinary THC-COOH levels significantly correlated with Marijuana Withdrawal Checklist (MWC) scores across the entire study duration (r = 0.248; p < 0.001). Correlation between serial creatinine-adjusted THC-COOH ratios and serial MWC scores emerged as significant only in the sample with higher MWC scores (>11 points) at admission (n = 21; r = 0.247; p = 0.002). The aforementioned significant relationships have persisted when replacing the absolute THC-COOH-levels with the (relative) day-to-day change in urinary THC-COOH levels. MWC scores were significantly correlated with the Clinical Global Impression-Severity (CGI-S; r = 0.812; p < 0.001). Females showed a significantly slower decline in urine THC-COOH levels and prolonged CWS course characterized by substantial illness severity (per CGI-S), occurring in nearly 30% of cases.Conclusion: Urine cannabinoid levels (THC-COOH) determined by POC assay significantly predicted CWS severity (moderate correlation), guiding detoxification treatment duration. In patients with MWC > 11 points upon admission, creatinine-adjusted THC-COOH ratios also significantly predicted CWS severity—again with moderate effect size. Females showed prolonged urinary THC-COOH elimination and cannabis withdrawal.

Biotin Interference in Point of Care HIV Immunoassay.

The use of high concentrations of biotin as a dietary supplement to improve hair, skin, and nail quality has increased in the United States over the past few years. High concentrations of biotin have been shown to interfere with some diagnostic assays that use streptavidin–biotin interactions as one of the steps in the assay. The objective of this report is to evaluate potential biotin interference on the analytical and clinical sensitivity of a point of care (POC) antigen–antibody combo HIV-1 assay. We spiked biotin at concentrations ranging from 12.5 to 400 ng/mL into serum and plasma containing HIV-1 subtype B p24 antigen derived from culture supernatant. The p24 antigen was present in the matrices at 30 pg/mL. Fifty microliters of each sample was applied to Alere Determine HIV-1/2 Ag/Ab combo assay strips in duplicate and results were read by eye after 20 to 30 min. Biotin interfered with detection of HIV-1 p24 in serum and plasma. HIV-1 p24 was not detected at 30 pg/mL p24 when biotin was present at 200 ng/mL concentration. Our study demonstrated that elevated levels of biotin in samples may interfere with POC assays. It is important to consider biotin supplements as potential sources of falsely increased or decreased test results, especially in cases wherein supplementation cannot be ruled out.

Point-of-Care Assays Could Be Useful for Therapeutic Drug Monitoring of IBD Patients in a Proactive Strategy with Adalimumab.

The objective of the study was to evaluate whether Point-of-Care (POC) assays are equivalent to ELISAs for measuring residual trough levels of adalimumab (ADA) in a cohort of Inflammatory Bowel Disease (IBD) patients. ADA trough levels obtained by POC assays were used to optimize patients in daily clinical practice. Different assays (three ELISAs (Enzyme-Linked ImmunoSorbent Assay) from two different suppliers and two POC assays) were compared to measure ADA trough levels in a first cohort of 31 IBD patients. All assays revealed a high correlation within the assays, ranging from 0.86 to 0.99. Cut-off values were always higher with ELISAs than with POC assays. Then, a small prospective clinical study with a second cohort of 37 IBD patients was performed to compare POC assays and ELISAs for their ability to optimize patients on the basis of the measured ADA trough levels. The use of a POC assay to monitor ADA trough levels did not improve the follow-up of patients with loss of response, as they were always optimized whatever their ADA residual rate. For patients in clinical remission, a POC assay can be useful in some clinical situations to maintain or de-escalate ADA doses according to the measured trough levels. In conclusion, different assays for ADA monitoring are quite equivalent. A POC assay could be only useful for a proactive strategy for asymptomatic patients with a sub-therapeutic dose of ADA, but new therapeutic thresholds need to be identified.

Whole-Blood Validation of a New Point-of-care Equine Serum Amyloid A Assay

Serum amyloid A (SAA) is considered a major acute phase protein (APP) in horses. Serum amyloid A stall-side assays are commercially available to assess the inflammatory response of patients with various infectious and noninfectious conditions. The objective of this study was to determine the analytical performance of a new point-of-care (POC) assay for the measurement of SAA in whole blood and plasma of horses. One hundred and sixty blood samples were collected from 60 horses at various time points after immunization with an equine core vaccine. Analytical validation of the SAA POC assay included the measurement of SAA in whole blood and plasma, assessment of linearity and precision, and comparison of the SAA POC results with those obtained with a validated turbidimetric immunoassay (TIA). The SAA POC assay yielded similar results in whole blood and plasma (P > .05), and the results were positively correlated with the TIA (R2 = 0.964). The assay displayed solid linearity throughout the detection range of ≤ 20 to 3,000 μg/mL (R2 = 0.984) with inter-assay and intra-assay coefficients of variation ranging from 7.8% to 13.3% and 5.7% to 12.0%, respectively. The new SAA POC assay was able to reliably measure SAA in both whole blood and plasma. Similar to previously validated assays, the new SAA POC assay is a valuable tool to investigate the inflammatory response in various clinical diseases of horses.

Current diagnostic tools for coronaviruses-From laboratory diagnosis to POC diagnosis for COVID-19.

The Coronavirus‐2019 (COVID‐19) pandemic has put tremendous strain on healthcare systems worldwide. It is challenging for clinicians to differentiate COVID‐19 from other acute respiratory tract infections via clinical symptoms because those who are infected display a wide range of symptoms. An effective, point‐of‐care (POC) diagnostic tool could mitigate healthcare system strain, protect healthcare professionals, and support quarantine efforts. We believe that a POC tool can be developed that would be rapid, easy to use, and inexpensive. It could be used in the home, in resource‐limited areas, and even in clinical settings. In this article, we summarize the current state of COVID‐19 diagnostic methods and make a case for an all‐in‐one, highly sensitive POC assay that integrates antibody detection, protein detection, and serum cytokine detection to diagnose COVID‐19 infection. We believe this article will provide insights into the current state of diagnostics for COVID‐19, and promote additional research and tool development that could be exceptionally impactful.

Establishment and Characterization of an Empirical Biomarker SS/PV-ROC Plot Using Results of the UBC® Rapid Test in Bladder Cancer.

Background: This investigation included both a study of potential non-invasive diagnostic approaches for the bladder cancer biomarker UBC® Rapid Test and a study including comparative methods about sensitivity–specificity characteristic (SS-ROC) and predictive receiver operating characteristic (PV-ROC) curves that used bladder cancer as a useful example. Methods: The study included 289 urine samples from patients with tumors of the urinary bladder, patients with non-evidence of disease (NED) and healthy controls. The UBC® Rapid Test is a qualitative point of care assay. Using a photometric reader, quantitative data can also be obtained. Data for pairs of sensitivity/specificity as well as positive/negative predictive values were created by variation of threshold values for the whole patient cohort, as well as for the tumor-free control group. Based on these data, sensitivity–specificity and predictive value threshold distribution curves were constructed and transformed into SS-ROC and PV-ROC curves, which were included in a single SS/PV-ROC plot. Results: The curves revealed TPP-asymmetric improper curves which cross the diagonal from above. Evaluation of the PV-ROC curve showed that two or more distinct positive predictive values (PPV) can correspond to the same value of a negative predictive value (NPV) and vice versa, indicating a complexity in PV-ROC curves which did not exist in SS-ROC curves. In contrast to the SS-ROC curve, the PV-ROC curve had neither an area under the curve (AUC) nor a range from 0% to 100%. Sensitivity of the qualitative assay was 58.5% and specificity 88.2%, PPV was 75.6% and NPV 77.3%, at a threshold value of approximately 12.5 µg/L. Conclusions: The SS/PV-ROC plot is a new diagnostic approach which can be used for direct judgement of gain and loss of predictive values, sensitivity and specificity according to varied threshold value changes, enabling characterization, comparison and evaluation of qualitative and quantitative bioassays.

CdSe/CdS/ZnS nanocrystals decorated with Fe3O4 nanoparticles for point-of-care optomagnetic detection of cancer biomarker in serum

Early diagnosis of a progressive cancer disease is currently limited due to lack of adequate point-of-care (PoC) diagnostic tools. PoC diagnosis enables detecting early signs of a disease and pave way to disease prevention. Here, we developed an immuno-optomagnetic quantum dots based PoC assay for early detection of a cancer biomarker, human epidermal growth factor receptor-2 (hErbB2) protein in serum. This assay utilizes immuno-optomagnetic quantum dots (MQDs-Ab2) nanoarchitectures with unique orientation comprised of core CdSe/CdS/ZnS QD nanocrystals surrounded by layers of magnetic Fe3O4 nanoparticles (MNPs) and a bioactivated borofloat PoC-chip (Ab1). The MQDs-Ab2 and the PoC-chips were designed to bind same hErbB2 analyte, but both bind with distinct epitopes. First, free hErbB2 protein from serum was captured by MQDs-Ab2 forming immuno-optomagnetic MQDs-Ab2-hErbB2 complex, which was isolated and presented to bioactivated PoC-chips. The immuno-optomagnetic signal from chips was directly visualized by naked-eye after exposing chips with a UV-torch and the signal was directly measured within 30 min by computing RGB intensities using a smartphone camera and a colorimeter-app. The immuno-optomagnetic QDs based PoC-chip exhibited the detection range of 620 pg mL−1 ∼5 ng mL−1 hErbB2 protein in serum. The MQDs-Ab2 rendered biospecificty, magnetic and optical functionality to PoC detection and provided advantages of speed, sensitivity, portability and low-cost, which is most desired in resource limited settings. The developed PoC chip assay provided an accurate quantitative cancer biomarker detection with high sensitivity and specificity that required no laboratory equipment and is also potentially applicable to the detection of many other biomarkers.

Analytical performance and user-friendliness of five novel point-of-care D-dimer assays

D-dimer testing combined with a clinical assessment has become a standard pathway for ruling-out venous thromboembolism (VTE). Recently, novel Point-of-Care (POC) D-dimer assays have been introduced, enabling low-volume blood sampling for rapid exclusion of VTE in a one-step procedure. We assessed the analytical validity and user-friendliness of a set of these novel POC D-dimer assays, and compared the results with a standard laboratory assay. Plasma samples were run on our reference assay (STA-Liatest D-di PLUS®) and five POC assays: Nano-Checker 710®, AFIAS-1®; iChroma-II®; Standard F200® and Hipro AFS/1®). After evaluating imprecision, Pearson Product-Moment correlation coefficients were calculated, Passing Bablok regression was performed and Bland-Altman plots were generated. User-friendliness was evaluated using the System Usability Scale (SUS). A set of 238 plasma samples of patients clinically suspected of VTE in general practice was available for analysis. Only one POC D-dimer assay (Nano-Checker 710) demonstrated an insufficient degree of imprecision. Pearson correlation coefficients and mean biases ranged from 0.68 to 0.93 and −165 to −53 μg/L respectively, and concordance with our reference assay varied from 71.8% to 89.5% using a 500 μg/L cut-off point. While we found considerable variation in overall user-friendliness, most devices were judged easy to use. In view of our findings regarding analytical performance and user-friendliness, we consider most of the novel POC D-dimer assays can be used in settings outside of the laboratory such as general practice, combining the possibility of multi-testing with low-volume capillary blood sampling and processing times of less than 15 min.

Evaluation of the Performance of a Point-of-Care Test for Chlamydia and Gonorrhea

Rates of chlamydial and gonococcal infection continue to increase in the United States, as do the associated costs of untreated infections. Improved diagnostic technologies that support testing and treating in 1 clinical visit are critical to advancing efforts to control the rates of chlamydial and gonococcal infection. To evaluate the clinical performance of a point-of-care (POC) molecular diagnostic assay for the detection of chlamydia and gonorrhea. A noninterventional, cross-sectional clinical study was conducted from September 18, 2018, through March 13, 2019, at sexually transmitted infection (STI), HIV, family planning, and obstetrics and gynecology clinics where STI screening is routine, using a convenience sample and comparing commercially available assays with a new 30-minute POC assay. Patients included were those eligible for STI screening or diagnostic testing who had not taken antibiotics effective against chlamydia or gonorrhea within the previous 28 days. Four vaginal swab samples were collected from women and a first-catch urine sample was obtained from men. A composite infection status was used to classify participants as infected if 2 or more comparator results were positive, as not infected if 2 or more comparator samples were negative, and as unevaluable if 1 result was invalid and the other 2 results did not agree with each other. Swab samples from 1523 women (median age, 27 years [interquartile range, 17-37 years]), 817 (53.6%) of whom presented with symptoms, and 922 men (median age, 29 years [interquartile range, 17-41 years]), 308 (33.4%) of whom were symptomatic, were tested. For chlamydia, sensitivity of the new POC assay was 96.1% (95% CI, 91.2%-98.3%) for women and 92.5% (95% CI, 86.4%-96.0%) for men. For gonorrhea, sensitivity estimates were 100.0% (95% CI, 92.1%-100.0%) for women and 97.3% (95% CI, 90.7%-99.3%) for men. For chlamydia, specificity of the new POC assay was 99.1% (95% CI, 98.4%-99.5%) for women and 99.3% (95% CI, 98.4%-99.7%) for men. For gonorrhea, specificity estimates were 99.9% (95% CI, 99.5%-100%) for women and 100% (95% CI, 95.5%-100%) for men. Non-laboratory-trained personnel performed 94.8% of all tests (2318 of 2445) during the study. This study suggests that self-obtained vaginal swab samples were associated with performance equivalent to laboratory-based molecular diagnostics, which can support use of this POC assay in many settings. The availability of an easy-to-use, rapid (30-minute) molecular test for accurate detection of chlamydia and gonorrhea has the power to facilitate testing and treatment in a single patient visit for these STIs.

The Use of Active Melioidosis Detect TM in Early Diagnosis of Melioidosis in Hospital Tengku Ampuan Afzan and Hospital Sultanah Nur Zahirah

Introduction: Melioidosis is endemic in Malaysia and an important cause of sepsis. Current gold standard for diagnosis is by culture method,but its long procedure will delay the treatment leading to hospital-related mortality.Thus,a good rapid test is needed to reduce its mortality burden. Recently, Active Melioidosis Detect (AMD) have been shown to be useful. Objectives: (1)To measure the sensitivity and specificity of AMD. (2)To study the sensitivity and specificity of early morning urine AMD compared to spot urine AMD. Materials and method: A prospective crosssectional study of clinically suspected melioidosis patients in HTAA and HSNZ from April until December 2018. Blood and urine samples were tested with AMD. Test results were analysed for sensitivity, specificity,positive predictive value and negative predictive value. Results: A total of 89 patients were included in this study.The mean age is 52 years old, and 56.3% were male gender.64% of patients have diabetes mellitus.11 patients have positive blood culture for Bukholderia pseudomallei, 4 of them were tested positive for AMD.3 of them presented with septic shock (3.4%), however none died.The sensitivity of the AMD was 36.4% ([95% CI 12.4 to 68.4]) and the specificity was 66.7% ( [95% CI 46.0 to 82.8]) in all samples, with positive predictive value of 30.7% and negative predictive value of 72%.Blood samples have lower sensitivity of 9.1% ([95% CI 4.8 to 42.9]) with high specificity of 100% ([95% CI 84.5 to 100]). Urine spot samples have higher sensitivity compared to serum and morning urine, with 36.4% ([95%CI 12.4 to 68.4]) and specificity of 88.9% ([95% CI 69.7 to 97.1]). Conclusion: From this pilot study, this test requires further evaluation before incorporating as point of care assay.

LFRET, a novel rapid assay for anti-tissue transglutaminase antibody detection.

The diagnosis of celiac disease (CD) is currently based on serology and intestinal biopsy, with detection of anti-tissue transglutaminase (tTG) IgA antibodies recommended as the first-line test. Emphasizing the increasing importance of serological testing, new guidelines and evidence suggest basing the diagnosis solely on serology without confirmatory biopsy. Enzyme immunoassays (EIAs) are the established approach for anti-tTG antibody detection, with the existing point-of-care (POC) tests lacking sensitivity and/or specificity. Improved POC methods could help reduce the underdiagnosis and diagnostic delay of CD. We have previously developed rapid homogenous immunoassays based on time-resolved Förster resonance energy transfer (TR-FRET), and demonstrated their suitability in serodiagnostics with hanta- and Zika virus infections as models. In this study, we set out to establish a protein L -based TR-FRET assay (LFRET) for the detection of anti-tTG antibodies. We studied 74 patients with biopsy-confirmed CD and 70 healthy controls, with 1) the new tTG-LFRET assay, and for reference 2) a well-established EIA and 3) an existing commercial POC test. IgG depletion was employed to differentiate between anti-tTG IgA and IgG positivity. The sensitivity and specificity of the first-generation tTG-LFRET POC assay in detection of CD were 87.8% and 94.3%, respectively, in line with those of the reference POC test. The sensitivity and specificity of EIA were 95.9% and 91.9%, respectively. This study demonstrates the applicability of LFRET to serological diagnosis of autoimmune diseases in general and of CD in particular.

Analytical evaluation and clinical application of insulin and C-peptide by a whole blood, lateral flow, point of care (POC) assay system

The analytical performance and clinical application of measuring insulin and connecting peptide (C-peptide) by point of care (POC) assay were evaluated. A POC assay system (SelexOn, Osang Healthcare Inc., Anyang-si, Korea) was evaluated for precision, linearity, limit of blank (LOB), and limit of detection (LOD). Method comparison was performed with the Cobas Elecsys insulin and C-peptide assay (Roche Diagnostics GmbH, Mannheim, Germany) using 215 and 201 patient specimens for insulin and C-peptide, respectively. For clinical application, insulin resistance indices were studied. Homeostasis model assessment (HOMA) 1 and 2, Quantitative insulin sensitivity check index (QUIKI), fasting insulin resistance index (FIRI), and other indices were evaluated. The coefficient of variation (CV) of imprecision for low, medium, and high concentrations was 10.8%1, 15.99%, and 12.05%, respectively, for insulin and 9.21%, 13.51%, and 13.77%, respectively, for C-peptide. The linearity was validated to 839.78 pmol/L for insulin and to 17.30 nmol/L for C-peptide. LOB and LOD were 8.05 and 9.72 pmol/L for insulin and 0.05 and 0.08 nmol/L for C-peptide, respectively. For the method comparison, the regression equation was y = 1.259x − 8.818 (r = 0.957) for insulin and y = 1.163x – 0.088 (r = 0.985) for C-peptide. The ROC value and overall accuracy were as follows: HOMA2 (C-peptide), 0.809, 79.7%; TyG, 0.788, 73.6%; CPR, 0.775, 74.8%; HOMA1, 0.725, 70.3%; QUIKI, 0.720, 70.3%; FIRI, 0.715, 70.1%; McAuley, 0.658, 65.1%; HOMA2 (Insulin), 0.645, 64.7%; Raynaud, 0.611, 61.4%, respectively. The POC assay system for insulin and C-peptide provided reliable results through a rapid and simple test that could be applied to clinical settings.

Analytical performances of the BD Veritor™ System for the detection of respiratory syncytial virus and influenzaviruses A and B when used at bedside in the pediatric emergency department

This study aims to evaluate the analytical performance of the BD Veritor™ rapid diagnostic assays (RDTs) for respiratory syncytial virus (RSV) and influenzaviruses when performed 24/7 at bedside by nurses in the pediatric emergency department (PED). The study was performed between 14/10/2015 and 19/03/2016 on nasopharyngeal aspirates (NPAs) collected from children consulting at the PED of the University Hospital of Saint-Etienne for bronchiolitis (RSV detection) or flu-like syndrome (influenzaviruses A/B detection). NPAs were tested 24/7 at the PED with the RDT and then sent to the Infectious Agents Department for routine analyses, first by immunofluorescence assay (IFA), then by nucleic acid amplification test (NAAT) considered as the gold standard in case of discrepancy between RDT and IFA results. For RSV detection, 205 NPAs was analyzed; the overall concordance between RDT and routine assays was of 97.6% (200/205). The sensitivity (Se), specificity (Sp), negative predictive value (NPV) and positive predictive value (PPV) were of 97.6% (160/164), 97.6% (40/41), 90.9% (40/44) and 99.4% (160/161), respectively. A total of 419 NPA was tested for influenzaviruses. For influenzavirus A, the overall concordance was of 98.8% (414/419); Se, Sp, NPV and PPV were of 100% (41/41), 98.7% (373/378), 100% (373/373) and 89.1% (41/46), respectively. For influenzavirus B, the overall concordance was of 97.9% (410/419); Se, Sp, NPV and PPV were of 96.6% (172/178), 98.8% (238/241), 97.5% (238/244) and 98.3% (172/175), respectively. Due to their excellent performances and their easy handle by non-laboratory personnel, these RDTs can be warmly recommended as point of care assays at the PED.

Clinical effect and cost-effectiveness of incorporation of point-of-care assays into early infant HIV diagnosis programmes in Zimbabwe: a modelling study

New point-of-care (POC) assays for early infant HIV diagnosis are costlier than conventional total nucleic acid assays, but could increase access to testing, shorten time to results, and expedite initiation of antiretroviral therapy. We aimed to assess the clinical benefits and cost-effectiveness of incorporating these POC assays into early infant diagnosis programmes in Zimbabwe. We used the Cost Effectiveness of Preventing AIDS Complications (CEPAC)-Pediatric model to examine the clinical benefits, costs, and cost-effectiveness of replacing conventional assays for early infant HIV diagnosis with POC assays at age 6 weeks in Zimbabwe. We simulated two strategies for early infant HIV diagnosis: conventional and POC. Modelled assays differed in sensitivity; specificity; time to, and probability of, return of results; and cost. Model outcomes included survival, life expectancy, and mean lifetime per-person treatment cost, which were reported separately for all HIV-exposed infants and all infants with HIV. We calculated incremental cost-effectiveness ratios with discounted (3% per year) costs and life expectancy from a health-care system perspective for all HIV-exposed infants. We judged incremental cost-effectiveness ratios of $1010 (Zimbabwe's annual gross domestic product per person) or less per year of life saved to be cost-effective. When conventional assays were used for early infant diagnosis, projected undiscounted life expectancy was 22·7 years for infants with HIV and 62·5 years for all HIV-exposed infants, at a cost of $610 per HIV-exposed infant. Use of POC assays for early infant HIV diagnosis improved projected undiscounted life expectancy to 25·5 years among infants with HIV and 62·6 years among HIV-exposed infants at a cost of $690 per HIV-exposed infant. At age 12 weeks, survival among all infants with HIV was 76·1% with the conventional testing strategy and 83·5% with the POC testing strategy. The incremental cost-effectiveness ratio of POC assays versus conventional assays for early infant diagnosis was $680 per year of life saved. When conventional assay characteristics remained constant, this ratio remained under the cost-effectiveness threshold as long as the specificity and sensitivity of the POC assay were greater than 92% and 65%, respectively. Our results were robust to plausible variations in POC assay cost, the probability of ART initiation, and probability of return of the results of POC testing. Compared with conventional assays, POC assays for early infant HIV diagnosis in Zimbabwe will improve survival, extend life expectancy, and be cost-effective for HIV-exposed infants. Elizabeth Glaser Pediatric AIDS Foundation, US National Institute of Allergy and Infectious Diseases, Eunice Kennedy Shriver National Institute of Child Health and Human Development, and Unitaid.

An aptamer based thermofluorimetric assay for ethanolamine

There is a great need for fast, simple and precise diagnostic assays capable of direct quantification of biomarkers in complex biological matrices. Yet, the commonly used techniques such as ELISA/Immunoassays are tedious and involve various steps e.g. blocking, washing and signal development. Moreover, most of these assays have very limited ability of detecting small molecules and have hardly any multiplexing capabilities. The gold standard and alternative, mass-spectrometry, however, depends upon expensive hardware and is incompatible with point of care (POC) diagnostics. As opposed to POC assays for proteins or larger targets where variable formats are readily available.Here, we present a simple, versatile and fast one-step assay for detecting a small molecule, ethanolamine as example. The assay makes use of commonly available qPCR machines to detect target-concentration dependent shifts in the melting temperatures of aptamer beacons. The method allows detection of ethanolamine in the low nM range without requiring tedious elaboration of assay conditions as required for molecular beacons at room temperature. If generalizable, it may change the situation of small molecule assays significantly.