Comparison of SARS-COV-2 nasal antigen test to nasopharyngeal RT-PCR in mildly symptomatic patients

AbstractIntroductionCOVID 19 has been vastly spreading since December 2019 and the medical teams worldwide are doing their best to limit its spread. In the absence of a vaccine the best way to fight it is by detecting infected cases early and isolate them to prevent its spread. Therefore, a readily available, rapid, and cost-effective test with high specificity and sensitivity for early detection of COVID 19 is required. In this study, we are testing the diagnostic performance of a rapid antigen detection test in mildly symptomatic cases. (RADT).MethodsThe study included 4183 patients who were mildly symptomatic. A nasal sample for the rapid antigen test and a nasopharyngeal sample was taken from each patient. Statistical analysis was conducted to calculate the sensitivity, specificity, positive predictive value, negative predictive value and kappa coefficient of agreement.ResultsThe prevalence of COVID 19 in the study population was 17.5% (733/4183). The calculated sensitivity and specificity were 82.1% and 99.1% respectively. Kappa’s coefficient of agreement between the rapid antigen test and RT-PCR was 0.859 (p < 0.001). A stratified analysis was performed and it showed that the sensitivity of the test improved significantly with lowering the cutoff Ct value to 24.ConclusionThe results of the diagnostic assessment of nasal swabs in the RADT used in our study are promising regarding the potential benefit of using them as a screening tool in mildly symptomatic patients. The diagnostic ability was especially high in cases with high viral load. The rapid antigen test is intended to be used alongside RT-PCR and not replace it. RADT can be of benefit in reducing the use of PCR.

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Role of Covid Antigen in the Diagnosis of Covid Positive in Obstetric Patients

10.53350/pjmhs2115103356 ◽

2021 ◽

Vol 15 (10) ◽

pp. 3356-3358

Author(s):

Ambreen Fatima ◽

Nidda Yaseen ◽

Amna Fareed ◽

Kashif Ali Samin ◽

Shumaela Kanwal ◽

...

Keyword(s):

Nucleic Acid ◽

Early Detection ◽

Negative Predictive Value ◽

Predictive Value ◽

False Negative ◽

Nucleic Acid Amplification ◽

Antigen Test ◽

Rt Pcr ◽

Cross Sectional ◽

Specificity And Sensitivity

Background and Aim: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) rapid emergence postured significant challenges on the health system in recent years. The early detection of cases is thought to be critical in preventing this pandemic by coronavirus disease (COVID-19), especially important in the obstetrical population due to theirs numerous interactions with another parturient when hospitalized for delivery. Therefore, the present study aimed to assess the COVID antigen test performance in COVID-positive obstetrics patients. Materials and Methods: This cross-sectional study was conducted on 1296 Covid-19 asymptomatic women admitted to the Obstetrics and Gynaecology Department of Muhammad Teaching Hospital & Medical College, Peshawar and Fauji Foundation Hospital, Rawalpindi for the duration of six months from February 2021 to July 2021. Antigen-based test rapid diagnostic test (RDT) was used for screening out COVID-19 positive obstetrics patients or women through nasopharyngeal swabs. Women with negative rapid antigen test results were confirmed with RT-polymers chain reaction test of nucleic acid amplification tests (NAAT). Ethical approval and informed consent were taken from the hospital ethical committee and each individual respectively. All the known positive COVID-19 patients during admission were excluded. SPSS version 24 was used for data analysis. Results: The overall prevalence of rapid antigen-positive tested patients was 13.2% (171/1296). The prevalence of positive tested women through rapid antigen test, Nucleic Acid Amplification Test (NAAT), and RT-PCR were 27 (2.1%), 51 (3.9%), and 93 (7.2%) respectively. Of the total 1296 rapid antigen tests, 27 were positive, and the false-negative confirmed positive by NAAT was 144.Thus the sensitivity of the rapid antigen test was 15.8% and the negative predictive value was 93.7%. Of the total 298 Nucleic Acid Amplification Tested had sensitivity and negative predictive value of 89.6% and 99.06% respectively. RT-PCR was carried out on 972 patients, positive diagnosed cases were 36 while 15 were initially negative and were positive with the test was repeated. The sensitivity and negative predictive value was 71.45% and 95.8% respectively. Conclusion: Our study found that Ag-RDT plays a significant role in SARS-CoV-2 early detection in infected individuals, with high specificity and sensitivity to disease infectious stage, whether symptomatic or asymptomatic, and can be used as a decision supported tool. Early detection of COVID-19 status in women admitted for delivery could benefit neonatal protection care. Keywords: Covid-19; Rapid antigen test; RT-PCR test

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Correlation of fine needle aspiration cytology and histopathology of neck swellings

International Journal of Otorhinolaryngology and Head and Neck Surgery ◽

10.18203/issn.2454-5929.ijohns20180986 ◽

2018 ◽

Vol 4 (3) ◽

pp. 648

Author(s):

C. S. Asha ◽

B. R. Suchit Roy

Keyword(s):

Salivary Gland ◽

Lymph Node ◽

Predictive Value ◽

Age Groups ◽

Invasive Procedure ◽

High Specificity ◽

Cost Effective ◽

Needle Aspiration ◽

Predictive Values ◽

Specificity And Sensitivity

Background: Neck swellings are a common clinical finding affecting all age groups. FNAC is a minimally invasive procedure helpful in the diagnosis of various neck swellings. The purpose of this study is to determine the accuracy of FNAC in the diagnosis of neck swellings by comparing it with the histopathology which is taken as the gold standard.Methods: A prospective study which included 90 patients who attended ENT and surgery departments of Government Medical College, Trivandrum with neck swellings from July 2006-2007. FNAC of the swelling was done and the FNAC results were compared with the histopathology results. The specificity, sensitivity, positive and negative predictive values and accuracy of FNAC were calculated. Results: Of the 90 patients, thyroid swelling formed the major group followed by lymph node, salivary gland and miscellaneous swellings. Thyroid swellings had a female predominance while the other three groups namely lymph node, salivary gland and miscellaneous groups showed a male preponderance. When the neck swellings namely thyroid, salivary gland, lymph node and miscellaneous group were taken into consideration as a whole, the sensitivity of FNAC for detecting malignancy was 64.3%. The specificity, positive predictive value, negative predictive value and accuracy were 97.4%, 81.8%, 93.7% and 92% respectively.Conclusions: FNAC can be rated as a safe, simple, reliable, cost effective and rapid diagnostic tool with high specificity and sensitivity for the initial evaluation of neck swellings.

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Evaluation of a novel, rapid antigen detection test for the diagnosis of SARS-CoV-2

PLoS ONE ◽

10.1371/journal.pone.0259527 ◽

2021 ◽

Vol 16 (11) ◽

pp. e0259527

Author(s):

Rainer Thell ◽

Verena Kallab ◽

Wolfgang Weinhappel ◽

Wolfgang Mueckstein ◽

Lukas Heschl ◽

...

Keyword(s):

Emergency Departments ◽

Point Of Care ◽

Gain Control ◽

Rapid Test ◽

High Viral Load ◽

Rt Pcr ◽

Likelihood Ratios ◽

Predictive Values ◽

Rapid Antigen Detection Test ◽

Sensitivity Specificity

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) is currently finally determined in laboratory settings by real-time reverse-transcription polymerase-chain-reaction (rt-PCR). However, simple testing with immediately available results are crucial to gain control over COVID-19. The aim was to evaluate such a point-of-care antigen rapid test (AG-rt) device in its performance compared to laboratory-based rt-PCR testing in COVID-19 suspected, symptomatic patients. Methods For this prospective study, two specimens each of 541 symptomatic female (54.7%) and male (45.3%) patients aged between 18 and 95 years tested at five emergency departments (ED, n = 296) and four primary healthcare centres (PHC, n = 245), were compared, using AG-rt (positive/negative/invalid) and rt-PCR (positive/negative and cycle threshold, Ct) to diagnose SARS-CoV-2. Diagnostic accuracy, sensitivity, specificity, positive predictive values (PPV), negative predictive value (NPV), and likelihood ratios (LR+/-) of the AG-rt were assessed. Results Differences between ED and PHC were detected regarding gender, age, symptoms, disease prevalence, and diagnostic performance. Overall, 174 (32.2%) were tested positive on AG-rt and 213 (39.4%) on rt-PCR. AG correctly classified 91.7% of all rt-PCR positive cases with a sensitivity of 80.3%, specificity of 99.1%, PPV of 98.3, NPV of 88.6%, LR(+) of 87.8, and LR(-) of 0.20. The highest sensitivities and specificities of AG-rt were detected in PHC (sensitivity: 84.4%, specificity: 100.0%), when using Ct of 30 as cut-off (sensitivity: 92.5%, specificity: 97.8%), and when symptom onset was within the first three days (sensitivity: 82.9%, specificity: 99.6%). Conclusions The highest sensitivity was detected with a high viral load. Our findings suggest that AG-rt are comparable to rt-PCR to diagnose SARS-CoV-2 in COVID-19 suspected symptomatic patients presenting both at emergency departments and primary health care centres.

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Evaluation of RNA Extraction-Free Method for Detection of SARS-CoV-2 in Salivary Samples for Mass Screening for COVID-19

BioMed Research International ◽

10.1155/2021/5568350 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

Sally A. Mahmoud ◽

Subhashini Ganesan ◽

Esra Ibrahim ◽

Bhagyashree Thakre ◽

Juliet G. Teddy ◽

...

Keyword(s):

Predictive Value ◽

Rna Extraction ◽

Screening Method ◽

High Sensitivity ◽

High Specificity ◽

Cost Effective ◽

Kappa Coefficient ◽

Nasopharyngeal Swab ◽

Rt Pcr ◽

Good Agreement

In this COVID-19 pandemic, there is a dire need for cost-effective and less time-consuming alternatives for SARS-CoV-2 testing. The RNA extraction-free method for detecting SARS-CoV-2 in saliva is a promising option. This study found that it has high sensitivity (85.34%), specificity (95.04%), and was comparable to the gold standard nasopharyngeal swab (NPS) sample tests. The method showed good agreement between salivary and NPS samples, with a kappa coefficient of 0.797. However, there are variations in the sensitivity and specificity based on the RT-PCR kit used. The Thermo Fisher Applied Biosystems showed high sensitivity, positive predictive value (PPV), and negative predictive value (NPV) but also showed a higher percentage of invalid reports. On the other hand, the BGI kit showed high specificity, better agreement (kappa coefficient) between the results of saliva and NPS samples, and higher correlation between the Ct values of saliva and NPS samples. Thus, the RNA extraction-free method for salivary sample serves as an effective alternative screening method for COVID-19.

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Predictive Evaluation on Cytological Sample of Metastatic Melanoma: The Role of BRAF Immunocytochemistry in the Molecular Era

Diagnostics ◽

10.3390/diagnostics11061110 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1110

Author(s):

Andrea Ronchi ◽

Marco Montella ◽

Federica Zito Marino ◽

Michele Caraglia ◽

Anna Grimaldi ◽

...

Keyword(s):

Metastatic Melanoma ◽

Molecular Analysis ◽

Predictive Value ◽

Diagnostic Performance ◽

Cost Effective ◽

Needle Aspiration ◽

Braf V600e ◽

Mutational Status ◽

Needle Aspiration Cytology ◽

Sensitivity Specificity

Background: Cutaneous malignant melanoma is an aggressive neoplasm. In advanced cases, the therapeutic choice depends on the mutational status of BRAF. Fine needle aspiration cytology (FNA) is often applied to the management of patients affected by melanoma, mainly for the diagnosis of metastases. The evaluation of BRAF mutational status by sequencing technique on cytological samples may be inconvenient, as it is a time and biomaterial-consuming technique. Recently, BRAF immunocytochemistry (ICC) was applied for the evaluation of BRAF V600E mutational status. Although it may be useful mainly in cytological samples, data about BRAF ICC on cytological samples are missing. Methods: We performed BRAF ICC on a series of 50 FNA samples of metastatic melanoma. BRAF molecular analysis was performed on the same cytological samples or on the corresponding histological samples. Molecular analysis was considered the gold standard. Results: BRAF ICC results were adequate in 49 out of 50 (98%) cases, positive in 15 out of 50 (30%) cases and negative in 34 out of 50 (68%) of cases. Overall, BRAF ICC sensitivity, specificity, positive predictive value and negative predictive value results were 88.2%, 100%, 100% and 94.1%, respectively. The diagnostic performance of BRAF ICC results was perfect when molecular evaluation was performed on the same cytological samples. Hyperpigmentation represents the main limitation of the technique. Conclusions: BRAF ICC is a rapid, cost-effective method for detecting BRAF V600E mutation in melanoma metastases, applicable with high diagnostic performance to cytological samples. It could represent the first step to evaluate BRAF mutational status in cytological samples, mainly in poorly cellular cases.

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The slipping slipper sign: a simple test with high specificity and positive predictive value for peripheral neuropathy among diabetic patients

Clinics and Practice ◽

10.4081/cp.2012.e51 ◽

2012 ◽

Vol 2 (2) ◽

pp. 51 ◽

Cited By ~ 2

Author(s):

Krystal A.T. Gayle ◽

Marshall K. Tulloch-Reid ◽

Rainford J. Wilks ◽

Trevor S. Ferguson

Keyword(s):

Peripheral Neuropathy ◽

Positive Predictive Value ◽

Diabetic Neuropathy ◽

Predictive Value ◽

High Specificity ◽

Diabetic Patients ◽

Simple Test ◽

Diabetes Clinic ◽

Sensitivity Specificity ◽

Single Question

This study evaluated the ability of the slipping slipper sign (defined as unknowingly losing a slipper while walking) to identify diabetic neuropathy in Jamaican patients. A single question was used to ascertain the presence of the slipping slipper sign (SSS) among 69 patients attending a diabetes clinic. Nurses assessed pain, vibration and pressure perception among the same patients in order to detect diabetic neuropathy. The sensitivity, specificity and positive predictive value for the SSS were calculated. Eight participants (men=5, women=3) reported positive SSS. The SSS had a sensitivity of 28.6%, specificity of 100% and positive predictive value (PPV) 100% for neuropathy on at least one of the three tests. These findings indicate that the SSS has high specificity and PPV for diabetic neuropathy but the sensitivity is low. The sign may be a useful adjuvant to conventional methods of screening for severe neuropathy

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Field evaluation of a rapid antigen test (Panbio™ COVID-19 Ag Rapid Test Device) for the diagnosis of COVID-19 in primary healthcare centers

10.1101/2020.10.16.20213850 ◽

2020 ◽

Cited By ~ 5

Author(s):

Eliseo Albert ◽

Ignacio Torres ◽

Felipe Bueno ◽

Dixie Huntley ◽

Estefanía Molla ◽

...

Keyword(s):

Primary Healthcare ◽

Rapid Test ◽

Field Evaluation ◽

Antigen Test ◽

Rt Pcr ◽

Test Device ◽

Specificity And Sensitivity ◽

Primary Healthcare Centers

AbstractWe evaluated the Panbio™ COVID-19 AG Rapid Test Device (RAD) for the diagnosis of COVID-19 in symptomatic patients attended in primary healthcare centers (n=412). Overall specificity and sensitivity of RAD was 100% and 79.6%, respectively, taking RT-PCR as the reference. SARS-CoV-2 could not be cultured from specimens yielding RT-PCR+/RAD- results.

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Respiratory Tularemia: Francisella Tularensis and Microarray Probe Designing

The Open Microbiology Journal ◽

10.2174/1874285801610010176 ◽

2016 ◽

Vol 10 (1) ◽

pp. 176-182 ◽

Cited By ~ 8

Author(s):

Reza Ranjbar ◽

Payam Behzadi ◽

Caterina Mammina

Keyword(s):

Dna Microarray ◽

Francisella Tularensis ◽

High Specificity ◽

Cost Effective ◽

High Rate ◽

Molecular Diagnostic ◽

Microarray Technology ◽

Microarray Probe ◽

Specificity And Sensitivity ◽

Oligo Microarray

Background:Francisella tularensis(F. tularensis) is the etiological microorganism for tularemia. There are different forms of tularemia such as respiratory tularemia. Respiratory tularemia is the most severe form of tularemia with a high rate of mortality; if not treated. Therefore, traditional microbiological tools and Polymerase Chain Reaction (PCR) are not useful for a rapid, reliable, accurate, sensitive and specific diagnosis. But, DNA microarray technology does. DNA microarray technology needs to appropriate microarray probe designing.Objective:The main goal of this original article was to design suitable long oligo microarray probes for detection and identification ofF. tularensis.Method:For performing this research, the complete genomes ofF. tularensissubsp.tularensisFSC198,F. tularensissubsp.holarcticaLVS,F. tularensissubsp.mediasiatica,F. tularensissubsp.novicida(F. novicidaU112), andF. philomiragiasubsp.philomiragiaATCC 25017 were studiedviaNCBI BLAST tool, GView and PanSeq Servers and finally the microarray probes were produced and processedviaAlleleID 7.7 software and Oligoanalyzer tool, respectively.Results:In thisin silicoinvestigation, a number of long oligo microarray probes were designed for detecting and identifyingF. tularensis. Among these probes, 15 probes were recognized as the best candidates for microarray chip designing.Conclusion:Calibrated microarray probes reduce the biasis of DNA microarray technology as an advanced, rapid, accurate and cost-effective molecular diagnostic tool with high specificity and sensitivity. Professional microarray probe designing provides us with much more facility and flexibility regarding preparation of a microarray diagnostic chip.

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Clinical Performance of the Spot Vision Photo Screener before and after Induction of Cycloplegia in Children

Journal of Ophthalmology ◽

10.1155/2019/5329121 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Konuralp Yakar

Keyword(s):

Positive Predictive Value ◽

Negative Predictive Value ◽

Predictive Value ◽

Clinical Performance ◽

High Specificity ◽

Screening Criteria ◽

Predictive Values ◽

Before And After ◽

Sensitivity Specificity ◽

Vision Screener

Aim. To compare the clinical performance of the Spot Vision Screener used to detect amblyopia risk factors (ARFs) in children before and after induction of cycloplegia; the children were referred because they met the screening criteria of the American Association for Pediatric Ophthalmology and Strabismus (AAPOS). Methods. The Spot Vision Screener and a standard autorefractometer were used to examine 200 eyes of 100 children aged 3–10 years, before and after cycloplegia induction, in terms of ARFs. Sensitivity, specificity, and positive and negative predictive values for the detection of significant refractive errors were measured using the AAPOS referral criteria. It was explored that Spot Screener data were affected by cycloplegia. The extent of agreement between cycloplegic/noncycloplegic photoscreening data and cycloplegic autorefraction measurements was assessed using Wilcoxon and Spearman correlation analyses. Results. The Spot’s sensitivity was improved from 60.9% to 85.3% and specificity from 94.9% to 87.4% with cycloplegia compared to cycloplegic standard autorefractometer results. The positive predictive value of Spot was 75.7%, and the negative predictive value was 90.4% without cycloplegia. With cycloplegia, the positive predictive value of Spot was 63.6% and the negative predictive value was 95.8%. Conclusions. The Spot Screener afforded moderate sensitivity and high specificity prior to cycloplegia. The sensitivity and negative predictive value improved after induction of cycloplegia. Examiners should be aware of the effects of cycloplegia on their findings.

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Bolus Residue Scale: An Easy-to-Use and Reliable Videofluoroscopic Analysis Tool to Score Bolus Residue in Patients with Dysphagia

International Journal of Otolaryngology ◽

10.1155/2015/780197 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 11

Author(s):

Nathalie Rommel ◽

Charlotte Borgers ◽

Dirk Van Beckevoort ◽

Ann Goeleven ◽

Eddy Dejaeger ◽

...

Keyword(s):

Rating Scale ◽

Intraclass Correlation ◽

Correlation Coefficients ◽

Posterior Pharyngeal Wall ◽

High Specificity ◽

Analysis Tool ◽

Pharyngeal Wall ◽

Specificity And Sensitivity ◽

Low Sensitivity ◽

Sensitivity Specificity

Background. We aimed to validate an easy-to-use videofluoroscopic analysis tool, the bolus residue scale (BRS), for detection and classification of pharyngeal retention in the valleculae, piriform sinuses, and/or the posterior pharyngeal wall.Methods. 50 randomly selected videofluoroscopic images of 10 mL swallows (recorded in 18 dysphagia patients and 8 controls) were analyzed by 4 experts and 6 nonexpert observers. A score from 1 to 6 was assigned according to the number of structures affected by residue. Inter- and intrarater reliabilities were assessed by calculation of intraclass correlation coefficients (ICCs) for expert and nonexpert observers. Sensitivity, specificity, and interrater agreement were analyzed for different BRS levels.Results. Intrarater reproducibility was almost perfect for experts (mean ICC 0.972) and ranged from substantial to almost perfect for nonexperts (mean ICC 0.835). Interjudge agreement of the experts ranged from substantial to almost perfect (mean ICC 0.780), but interrater reliability of nonexperts ranged from substantial to good (mean 0.719). BRS shows for experts a high specificity and sensitivity and for nonexperts a low sensitivity and high specificity.Conclusions. The BRS is a simple, easy-to-carry-out, and accessible rating scale to locate pharyngeal retention on videofluoroscopic images with a good specificity and reproducibility for observers of different expertise levels.

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