Sensitivity Of Point-of-care Test Research Articles

Performance of a Point-of-Care Test for the Rapid Detection of SARS-CoV-2 Antigen.

The rapid detection of infections caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is necessary in the ongoing pandemic. Antigen-specific point-of-care tests (POCT) may be useful for this purpose. Here, such a POCT (SARS-CoV-2 NADAL® COVID-19 Ag) was compared to a laboratory-developed triplex real-time polymerase chain reaction (RT-PCR) designed for the detection of viral nucleoprotein gene and two control targets. This RT-PCR served as a reference to investigate POCT sensitivity by re-testing upper respiratory tract (URT) samples (n = 124) exhibiting different SARS-CoV-2 loads in terms of RT-PCR threshold cycle (Ct) values. The optical intensities of the antigen bands were compared to the Ct values of the RT-PCR. The infectivity of various virus loads was estimated by inoculating Vero cells with URT samples (n = 64, Ct 17-34). POCT sensitivity varied from 100% (Ct < 25) to 73.1% (Ct ≤ 30); higher SARS-CoV-2 loads correlated with higher band intensities. All samples with a Ct > 30 were negative; among SARS-CoV-2 free samples (n = 10) no false-positives were detected. A head-to-head comparison with another POCT (Abbott, Panbio™ COVID-19 Ag Rapid Test) yielded similar results. Isolation of SARS-CoV-2 in cell-culture was successful up to a Ct value of 29. The POCT reliably detects high SARS-CoV-2 loads and rapidly identifies infectious individuals.

Comparison of Four Commercially Available Point-of-Care Tests to Detect Antibodies against Canine Parvovirus in Dogs.

Measuring antibodies to evaluate dogs’ immunity against canine parvovirus (CPV) is useful to avoid unnecessary re-vaccinations. The study aimed to evaluate the quality and practicability of four point-of-care (POC) tests for detection of anti-CPV antibodies. The sera of 198 client-owned and 43 specific pathogen-free (SPF) dogs were included; virus neutralization was the reference method. Specificity, sensitivity, positive and negative predictive value (PPV and NPV), and overall accuracy (OA) were calculated. Specificity was considered to be the most important indicator for POC test performance. Differences between specificity and sensitivity of POC tests in the sera of all dogs were determined by McNemar, agreement by Cohen’s kappa. Prevalence of anti-CPV antibodies in all dogs was 80% (192/241); in the subgroup of client-owned dogs, it was 97% (192/198); and in the subgroup of SPF dogs, it was 0% (0/43). FASTest® and CanTiCheck® were easiest to perform. Specificity was highest in the CanTiCheck® (overall dogs, 98%; client-owned dogs, 83%; SPF dogs, 100%) and the TiterCHEK® (overall dogs, 96%; client-owned dogs, 67%; SPF dogs, 100%); no significant differences in specificity were observed between the ImmunoComb®, the TiterCHEK®, and the CanTiCheck®. Sensitivity was highest in the FASTest® (overall dogs, 95%; client-owned dogs, 95%) and the CanTiCheck® (overall dogs, 80%; client-owned dogs, 80%); sensitivity of the FASTest® was significantly higher compared to the one of the other three tests (McNemars p-value in each comparison: <0.001). CanTiCheck® would be the POC test of choice when considering specificity and practicability. However, differences in the number of false positive results between CanTiCheck®, TiterCHEK®, and ImmunoComb® were minimal.

Point-of-Care diagnostic of SARS-CoV-2: knowledge, attitudes, and perceptions (KAP) of medical workforce in Italy.

Introduction.The present study aims to characterize knowledge, attitudes and beliefs in a sample of medical professionals towards point-of-care (POC) rapid tests for SARS-CoV-2 in Italy (April 2020).Material and Methods.A total of 561 professionals (42.6% males, 26.9% ≥ 50-year-old) compiled a specifically designed web questionnaire on characteristics of POC rapid tests. They were asked whether they would change their daily practice and make clinical decisions according to POC tests. Multivariate odds ratios (aOR) for predictors of propensity towards the aforementioned behavioral outcomes were calculated through regression analysis.Results.Overall, only 51.9% knew the official recommendations of the Italian Health Authorities for POC tests, while 26.0% of respondents considered POC tests for COVID-19 highly reliable. Still, 40.3% of respondents would change their daily practice because of such tests, and 38.5% would make clinical decisions based on their results. Knowledge of POC tests’s sensitivity and specificity was not associated with the assessed behavioral outcomes: main positive effectors were: perceived reliability and usefulness of rapid tests, acknowledging the existence of official recommendations, understanding the limited clinical implications of POC tests, and working as occupational physicians were characterized as negative effectors.Conclusions.Propensity of sampled professionals towards POC tests for COVID-19 was diffusely unsatisfying. While actual understanding of accuracy of such tests was not a main effector of propensity, previous experiences with other POC tests in daily practice, particularly among occupational physicians may have impaired overall acceptance of such instruments. (www.actabiomedica.it)

Diagnostic Accuracy of a Point-of-Care Test for Celiac Disease Antibody Screening among Infertile Patients

Background: Screening for celiac disease among infertile patients has been suggested. Several rapid point-of-care (POC) tests aimed at detecting celiac disease antibodies have been developed. It has been suggested that these POC tests can be implemented as a replacement for standard laboratory tests. Objective: To evaluatethe diagnostic accuracy of a POC test (Simtomax®) that detects celiac disease antibodies compared with standard laboratory tests when screening for celiac disease among patients referred for fertility treatment in 2 Danish fertility clinics. Methods: Serum samples were analyzed for IgA anti-tissue transglutaminase (TGA) as the reference standard test with a cutoff of ≥7 kU/L and by the index POC test based on IgA and IgG antibodies against deamidated gliadin peptides (DGP). In IgA deficiency, the reference standard test was IgG DGP with a cutoff of ≥7 kU/L. Participants answered a questionnaire on gluten intake, symptoms, and risk factors. Diagnostic confirmation was made by duodenal biopsies. IgA TGA/IgG DGP were used as the reference standard to calculate positive and negative predictive values. Results: A total of 622 men and women (51.6%) were enrolled during 2015. The reference standard IgA TGA/IgG DGP was positive in 7 participants (1.1% [95% CI 0.5–2.3]) and the POC test was positive in 84 participants (13.5% [95% CI 10.9–16.4]), 3 of whom also had positive reference standard tests. This yields a sensitivity of the index POC test of 42.9% (95% CI 9.9–81.6) and a specificity of 86.8% (95% CI 83.9–89.4). Positive and negative predictive values were 3.57% (95% CI 0.7–10.1) and 99.3% (95% CI 98.1–99.8). Conclusion: The sensitivity of the POC test was low; however, the specificity was moderately good. The POC test had a high negative predictive value in this low prevalent population but missed 1 patient with biopsy-confirmed celiac disease. However, because of many false-positive tests, it cannot be recommended as replacement for standard laboratory tests but rather as a triage test to decide if the standard serology tests should be performed.

Case-finding in primary care for coeliac disease: Accuracy and cost-effectiveness of a rapid point-of-care test.

BackgroundAn on-site, rapid, fingertip, whole-blood point-of-care test (POCT) is attractive for active case-finding of coeliac disease (CD) in primary care because of its simplicity.AimThe aim of this article is to assess the usefulness and cost-effectiveness of adult case-finding using a POCT based on deamidated gliadin peptide antibodies (IgA/IgG-DGP) in primary care for CD diagnosis.MethodsA case-finding study for CD was conducted by using an easy-to-use, on-site, whole-blood for IgA/IgG-DGP-based fingertip POCT compared with tTG2 in 350 individuals. Sample size was calculated based on 0.28% prevalence in the reference population. Duodenal biopsies for histology, intraepithelial lymphocytes and in situ deposition of tTG2 were obtained if tTG2 and/or POCT were positive. Accuracy and cost-effectiveness of strategies using serology or POCT were calculated.ResultsPrevalence of CD was 1.14% (95% CI, 0.3–3.4), almost double what was previously observed. Four patients were diagnosed with CD. tTG2 was positive in three (0.85%) and POCT in 29 (8.2%). Sensitivity of POCT for CD was 100%, specificity 93%, PPV 14%, and NPV 100%. POCT followed by duodenal biopsy was the most cost-effective approach in our setting (standard diagnosis: €13,033/case; POCT + duodenal biopsy: €7360/case).ConclusionsA negative POCT allows ruling out CD in primary care, making it suitable for case-finding. POCT strategy was the most cost effective.

P09.13 Impact and cost-effectiveness of point-of-care testing for chlamydia: accounting for geographic variation in infection burden and testing rates, health service configuration, and implementation strategy

Introduction Point-of-care tests (PoCTs) for Chlamydia trachomatis potentially improve control by reducing transmission through reduced treatment delay, reduced loss to follow up, and greater convenience for patients leading to increased testing. However, with ~3–5 fold variation in rates of Chlamydia testing and diagnosis across geographic settings in England, in assessing cost-effectiveness the epidemiological context needs to be considered. Methods We developed a transmission-dynamic model to capture geographic variation in rates of testing and diagnosis using current technology to allow assessment of the impact of implementing PoCTs in different clinical services in different localities. The model incorporates heterogeneity in sexual partner change rates and is stratified by age and sex. It uses behavioural and prevalence data from the Natsal national survey, and Public Health England surveillance data on testing and diagnosis rates. Uncertainty in natural history and behavioural parameters is captured by Monte Carlo methods. Health service reconfiguration using PoCT is considered, including rates of PoCT introduction and reduction in presumptive treatment. Results The model captures observed geographic variation in rates of testing and diagnosis in females and males, which affects the impact and cost-effectiveness of PoCT introduction. In general, whilst PoCTs may reduce incidence by increasing diagnosis and treatment, if sensitivity is lower than conventional testing then there is potentially increased transmission from false-negative patients. The net effect depends upon characteristics of the particular PoCT. Conclusion PoCT sensitivity and specificity are key determinants of whether replacing conventional testing is likely to reduce or increase the incidence of infection. Importantly, if the convenience of PoCT increases testing rates then diagnoses might initially increase even though incidence falls; interpretation of surveillance data needs to account for this. This work is the foundation of a user-friendly web-based tool assessing the (cost-) effectiveness of introducing PoCTs in different local settings. Disclosure of interest statement CED, ESS, NG, EHE, RHJ, YC, CML, and PJW thank Innovate UK for funding. PJW thanks the UK Medical Research Council for Centre funding (grant MR/K010174/1), and also thanks the UK National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Modelling Methodology at Imperial College London in partnership with Public Health England (PHE) for funding (grant HPRU-2012–10080). The funding sources had no involvement in the study design or conduct; the collection, analysis and interpretation of data; the preparation, review or approval of the manuscript; or the decision to submit the manuscript for publication. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR, the Department of Health, or Public Health England. CED was employed for part of the project by the National Chlamydia Screening Programme. The other authors declare no competing interests.

Fatigue and tiredness are common sequelae after TBE at long-term follow-up: A self-reported case-control study in Western Gotaland, Sweden

Fatigue and tiredness are common sequelae after TBE at long-term follow-up: A self-reported case-control study in Western Gotaland, Sweden

P55 Evaluation of NAAT and POCT for detecting Trichomonas vaginalis infection in women at a London sexual health clinic

BackgroundTV is a common infection in our clinic, but the true prevalence is likely to be higher since microscopy-the current diagnostic test has a low sensitivity. Nucleic Acid Amplification (NAAT)...