Comparing immunochromatography with latex antigen agglutination testing for the diagnosis of cryptococcosis in cats, dogs and koalas

2019 ◽  
Vol 58 (1) ◽  
pp. 39-46 ◽  
Author(s):  
Mark B Krockenberger ◽  
Caroline Marschner ◽  
Patricia Martin ◽  
George Reppas ◽  
Catriona Halliday ◽  
...  
Keyword(s):  
Gold Standard ◽  
Screening Test ◽  
Large Scale ◽  
Point Of Care ◽  
High Specificity ◽  
Agglutination Test ◽  
Test Results ◽  
Predictive Values ◽  
Cryptococcal Antigen ◽  
Rule Out

AbstractAlthough the point-of-care cryptococcal antigen lateral flow assay (LFA) has revolutionized the diagnosis of cryptococcosis in human patients, to date there has been no large-scale examination of this test in animals. We therefore assessed the LFA in cats, dogs and koalas suspected of having cryptococcosis. In sum, 528 serum specimens (129 from cats, 108 from dogs, 291 from koalas) were tested using the LFA and one of two commercially available latex cryptococcal antigen agglutination test (LCAT) kits. The LCAT is a proven and well-accepted method in veterinary patients and therefore taken as the “gold standard” against which the LFA was compared. The LFA achieved a sensitivity of 92%, 100%, and 98% in cats, dogs, and koalas, respectively, with corresponding negative predictive values of 94%, 100%, and 98%. The specificity of the LFA was 81%, 84%, and 62% for cats, dogs, and koalas, respectively, with corresponding positive predictive values of 76%, 48%, and 69%. These findings suggest the most appropriate role for the LFA is as a screening test to rule out a diagnosis of cryptococcosis in cats, dogs, and koalas. Point-of-care accessibility makes it equally suited for use in the field and as a cage-side test in veterinary hospitals. The suboptimal specificity of the LFA makes it less suited to definitive confirmation of cryptococcosis in animals; therefore, all LFA-positive test results should be confirmed by LCAT testing. The discrepancy between these observations and the high specificity of the LFA in humans may reflect differences in the host-pathogen interactions amongst the species.

scholarly journals 674. Evaluation of the Access Bio CareStart™ Rapid SARS-CoV-2 Antigen Test in Asymptomatic Individuals Tested at a Community Mass-testing Program in Western Massachusetts

2021 ◽  
Vol 8 (Supplement_1) ◽  
pp. S439-S439
Author(s):  
Wilfredo Matias ◽  
Sara suliman ◽  
Isabel Fulcher ◽  
Francisco Molano ◽  
Shannon Collins ◽  
...  
Keyword(s):  
Point Of Care ◽  
Quantitative Polymerase Chain Reaction ◽  
Rapid Test ◽  
High Specificity ◽  
Population Data ◽  
Performance Characteristics ◽  
Test Results ◽  
Antigen Test ◽  
Predictive Values ◽  
Cycle Threshold

Abstract Background Point-of-care antigen-detecting rapid diagnostic tests (RDTs) to detect Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) represent a scalable tool for surveillance of active SARS-CoV-2 infections in the population. Data on the performance of these tests in real-world community settings will be paramount for their implementation to combat the COVID-19 pandemic. Methods We evaluated the performance characteristics of the CareStartTM COVID-19 Antigen Test (CareStart) in a community testing site in Holyoke, Massachusetts. We compared CareStart to a SARS-CoV-2 reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) reference, both using anterior nasal swab samples. We calculated the sensitivity, specificity, and the expected positive and negative predictive values at different SARS-CoV-2 prevalence estimates. Results We performed 666 total tests on 591 unique individuals. 573 (86%) were asymptomatic. There were 52 positive tests by RT-qPCR. The sensitivity of CareStart was 49.0% (95% Confidence Interval (CI): 34.8 – 63.4) and specificity was 99.5% (95% CI: 98.5 – 99.9). Among positive RT-qPCR tests, the median cycle threshold (Ct) was significantly lower in samples that tested positive on CareStart. Using a Ct less than or equal to 30 as a benchmark for positivity increased the sensitivity of the test to 64.9% (95% CI: 47.5 – 79.8). Performance characteristics of CareStart test results benchmarked against the RT-qPCR gold standard (excluding undetermined results). Examples of images of CareStart rapid test showing variable band intensities. N2 gene RT-qPCR Cycle threshold (Ct) values corresponding to positive and negative CareStart rapid antigen test results for all RT-qPCR positive samples (n=52). Conclusion Our study shows that CareStart has a high specificity and moderate sensitivity. The utility of RDTs, such as CareStart, in mass implementation should prioritize use cases in which a higher specificity is more important, such as triage tests to rule-in active infections in community surveillance programs. Disclosures All Authors: No reported disclosures

scholarly journals Point-of-care ultrasound to diagnose appendicitis in a Canadian emergency department

CJEM ◽  
2018 ◽  
Vol 20 (5) ◽  
pp. 732-735 ◽  
Author(s):  
Sameer Sharif ◽  
Steven Skitch ◽  
Dean Vlahaki ◽  
Andrew Healey
Keyword(s):  
Gold Standard ◽  
Point Of Care ◽  
High Specificity ◽  
Point Of Care Ultrasound ◽  
Likelihood Ratios ◽  
Test Characteristics ◽  
Patient Morbidity ◽  
Additional Imaging ◽  
Sensitivity Specificity ◽  
Diagnostic Delays

ABSTRACTObjectivesAppendicitis is a common surgical condition that frequently requires diagnostic imaging. Abdominal computed tomography (CT) is the gold standard for diagnosing appendicitis. Ultrasound offers a radiation-free modality; however, its availability outside business hours is limited in many emergency departments (EDs). The purpose of this study is to evaluate the test characteristics of emergency physician-performed point-of-care ultrasound (POCUS) to diagnose appendicitis in a Canadian ED.MethodsA health records review was performed on all ED patients who underwent POCUS to diagnose appendicitis from December 1, 2010 to December 4, 2015. The sensitivity, specificity, and likelihood ratios were calculated. The gold standard used for diagnosis was pathology, laparoscopy, CT scans, and a radiologist-performed ultrasound.ResultsNinety patients were included in the study, and 24 were diagnosed with appendicitis on POCUS. Ultimately, 18 were confirmed to have appendicitis through radiologist-performed imaging, laparoscopy, and pathology. The sensitivity and specificity of POCUS to diagnose appendicitis were 69.2% (95% CI, 48.1%-84.9%) and 90.6% (95% CI, 80.0%-96.1%), respectively.ConclusionPOCUS has a high specificity for diagnosing acute appendicitis and has very similar characteristics to those of a radiologist-performed ultrasound. These findings are consistent with the current literature and have the potential to decrease patient morbidity, diagnostic delays, ED length of stay, and need for additional imaging.

A new likelihood approach to inference about predictive values of diagnostic tests in paired designs

2016 ◽  
Vol 27 (2) ◽  
pp. 541-548 ◽  
Author(s):  
Tsung-Shan Tsou
Keyword(s):  
Diagnostic Tests ◽  
Screening Test ◽  
Score Test ◽  
Real Data ◽  
Test Results ◽  
Multinomial Model ◽  
Test Statistic ◽  
Predictive Values ◽  
Minimum Number ◽  
Likelihood Approach

Intuitively, one only needs patients with two positive screening test results for positive predictive values comparison, and those with two negative screening test results for contrasting negative predictive values. Nevertheless, current existing methods rely on the multinomial model that includes superfluous parameters unnecessary for specific comparisons. This practice results in complex statistics formulas. We introduce a novel likelihood approach that fits the intuition by including a minimum number of parameters of interest in paired designs. It is demonstrated that our robust score test statistic is identical to a newly proposed weighted generalized score test statistic. Simulations and real data analysis are used for illustration.

scholarly journals ASSESSMENT OF PERFORMANCE AND IMPLEMENTATION CHARACTERISTICS OF RAPID POINT OF CARE SARS-CoV-2 ANTIGEN TESTING IN KENYA

2021 ◽  
Author(s):  
Jesse Gitaka ◽  
Eva Muthamia ◽  
Samuel Mbugua ◽  
Mary Mungai ◽  
Gama Bandawe ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Test Performance ◽  
Gold Standard ◽  
Point Of Care ◽  
Turnaround Time ◽  
Ease Of Use ◽  
Control Measures ◽  
Antigen Test ◽  
Rt Pcr ◽  
Predictive Values

Abstract Background: The COVID-19 pandemic has resulted in a need for rapid identification of infectious cases. Testing barriers have prohibited adequate screening for SARS COV2, resulting in significant delays in treatment provision and commencement of outbreak control measures. This study aimed to generate evidence on the performance and implementation characteristics of the BD Veritor rapid antigen test as compared to the gold standard test for diagnosis of SARS COV2 in Kenya. Methods: This was a field test performance evaluation in symptomatic and asymptomatic adults undergoing testing for SARS COV2. Recruited participants were classified as SARS-CoV2-positive based on the locally implemented gold standard reverse transcription polymerase chain reaction (RT-PCR) test performed on nasopharyngeal swabs. 272 antigen tests were performed with simultaneous gold standard testing, allowing us to estimate sensitivity, specificity, positive and negative predictive values for the BD Veritor rapid antigen test platform. Implementation characteristics were assessed using the Consolidated Framework for Implementation Research for feasibility, acceptability, turn-around time, and ease-of-use metrics. Results and Discussion: We enrolled 97 PCR negative symptomatic and 128 PCR negative asymptomatic, and 28 PCR positive symptomatic and 19 PCR positive asymptomatic participants. Compared to the gold standard, the sensitivity of the BD Veritor antigen test was 94% (95% confidence interval [CI] 86.6 to 100.0) while the specificity was 98% (95% confidence interval [CI] 96 to 100). The sensitivity of BD Veritor antigen test was higher among symptomatic (100%) compared to asymptomatic (84%) participants, although this difference was not statistically significant. There was also a lack of association between cycle threshold value and sensitivity of BD Veritor test. The BD Veritor test had quick turnaround time and minimal resource requirements, and laboratory personnel conducting testing felt that it was easier to use than the gold standard RT-PCR. Conclusion: The BD Veritor rapid antigen test exhibited excellent sensitivity and specificity when used to detect SARS-CoV-2 infection among both symptomatic and asymptomatic individuals in varied population settings in Kenya. It was feasible to implement and easy to use, with rapid turnaround time.

scholarly journals Diagnostic performance and clinical implications of rapid SARS-CoV-2 antigen testing in Mexico using real-world nationwide COVID-19 registry data

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256447
Author(s):  
Omar Yaxmehen Bello-Chavolla ◽  
Neftali Eduardo Antonio-Villa ◽  
Luisa Fernández-Chirino ◽  
Enrique C. Guerra ◽  
Carlos A. Fermín-Martínez ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Diagnostic Performance ◽  
Large Scale ◽  
Characteristic Curve ◽  
False Negative ◽  
High Specificity ◽  
Adverse Outcomes ◽  
Clinical Implications ◽  
Predictive Values ◽  
Qrt Pcr

Background SARS-CoV-2 testing capacity is important to monitor epidemic dynamics and as a mitigation strategy. Given difficulties of large-scale quantitative reverse transcription polymerase chain reaction (qRT-PCR) implementation, rapid antigen tests (Rapid Ag-T) have been proposed as alternatives in settings like Mexico. Here, we evaluated diagnostic performance of Rapid Ag-T for SARS-CoV-2 infection and its associated clinical implications compared to qRT-PCR testing in Mexico. Methods We analyzed data from the COVID-19 registry of the Mexican General Directorate of Epidemiology up to April 30th, 2021 (n = 6,632,938) and cases with both qRT-PCR and Rapid Ag-T (n = 216,388). We evaluated diagnostic performance using accuracy measures and assessed time-dependent changes in the Area Under the Receiver Operating Characteristic curve (AUROC). We also explored test discordances as predictors of hospitalization, intubation, severe COVID-19 and mortality. Results Rapid Ag-T is primarily used in Mexico City. Rapid Ag-T have low sensitivity 37.6% (95%CI 36.6–38.7), high specificity 95.5% (95%CI 95.1–95.8) and acceptable positive 86.1% (95%CI 85.0–86.6) and negative predictive values 67.2% (95%CI 66.2–69.2). Rapid Ag-T has optimal diagnostic performance up to days 3 after symptom onset, and its performance is modified by testing location, comorbidity, and age. qRT-PCR (-) / Rapid Ag-T (+) cases had higher risk of adverse COVID-19 outcomes (HR 1.54 95% CI 1.41–1.68) and were older, qRT-PCR (+)/ Rapid Ag-T(-) cases had slightly higher risk or adverse outcomes and ≥7 days from symptom onset (HR 1.53 95% CI 1.48–1.59). Cases detected with rapid Ag-T were younger, without comorbidities, and milder COVID-19 course. Conclusions Rapid Ag-T could be used as an alternative to qRT-PCR for large scale SARS-CoV-2 testing in Mexico. Interpretation of Rapid Ag-T results should be done with caution to minimize the risk associated with false negative results.

scholarly journals A Study Utilizing Mobile E-Health and Self-Acquired Cervical Screening in Health Clinics

2018 ◽  
Vol 4 (Supplement 2) ◽  
pp. 213s-213s
Author(s):  
Y.L. Woo ◽  
N.H. Nasir ◽  
J. Kanapathy ◽  
Z. Mohd Said
Keyword(s):  
Mobile Technology ◽  
Screening Test ◽  
Point Of Care ◽  
Cervical Screening ◽  
Pilot Project ◽  
Message Delivery ◽  
Test Results ◽  
Cross Sectional ◽  
Hpv Test ◽  
Hpv Screening

Background: Malaysia continues to have a high incidence of cervical cancer with a relatively high mortality rate due to late presentation. Pilot Project R.O.S.E was a cross-sectional study to assess acceptability, feasibility and reach of a cervical screening strategy that utilizes self-collected, point-of-care HPV testing in primary care settings. Within this study, mobile SMS technology was used to register patients into a cervical screening registry and to deliver the HPV test results. Aim: To assess the feasibility, acceptability, advantages and limitations of the use of mobile SMS technology to deliver HPV screening test results. Methods: Invitation for cervical screening was offered to women aged 30 to 65 years who are presenting to these clinics for care, or accompanying another individual. Upon agreeing to do the test, the nurse registered the woman's details and mobile number. A mobile phone verification SMS is triggered at this point. HPV results were delivered to women via mobile SMS within 3 working days. Phone-based surveys were conducted on randomly selected screened positives and screened negative women to ascertain acceptability of the screening and the usage of mobile technology. Results: Ninety percent of participants received their SMS results without any hitches. Ten percent of participants experienced problems with receiving their results SMS. Further investigations revealed that there were various reasons for message delivery failure. Posttest surveys revealed that majority of participants were satisfied with the use of mobile technology to receive HPV screening test results. Conclusion: This study suggests that the use of mobile SMS technology for delivery of HPV screening test results is feasible and acceptable. However, measures should be taken to overcome technology related failures. The findings of this implementation research may help to inform the design of future mobile SMS technology usage within health settings in Malaysia.

Diagnostic value of culture results from aqueous tap versus vitreous tap in cases of bacterial endophthalmitis

2021 ◽  
pp. bjophthalmol-2021-318916
Author(s):  
Abdulrahman F AlBloushi ◽  
Sofia Ajamil-Rodanes ◽  
Ilaria Testi ◽  
Catherine Wagland ◽  
Nadine Grant-McKenzie ◽  
...  
Keyword(s):  
Gold Standard ◽  
Late Onset ◽  
Cohort Analysis ◽  
Positive Culture ◽  
High Specificity ◽  
Coagulase Negative Staphylococcus ◽  
Aqueous Sample ◽  
Aqueous Samples ◽  
Predictive Values ◽  
Bacterial Endophthalmitis

ObjectiveTo investigate the concordance between aqueous and vitreous tap culture results among different types of bacterial endophthalmitis.Methods and analysisThis retrospective cohort analysis included all cases diagnosed with endophthalmitis at Moorfields Eye Hospital between January 2008 and March 2020. Aqueous and vitreous samples obtained simultaneously at presentation. Samples were evaluated for sensitivity, specificity, negative and positive predictive values.ResultsA total of 217 patients (217 eyes) were included in the study. Postsurgical endophthalmitis was the most common type of endophthalmitis and diagnosed in 35.9% of the cases. The rate of positive culture results was 32.2% from vitreous tap and 21.7% from aqueous tap. The culture yield through vitreous sampling was 15.7% when aqueous culture results were negative, and in 5.1%, the aqueous sample was positive when the vitreous tap results were negative. Considering the vitreous tap as the gold standard, aqueous sample culture results showed a statistically significant high specificity and positive predictive values in cases of postsurgical endophthalmitis, late-onset endophthalmitis associated with glaucoma procedures, postintravitreal injection and endophthalmitis associated with bacterial keratitis. Coagulase Negative Staphylococcus was the most common organism isolated from vitreous and aqueous samples.ConclusionsEven though the sensitivity and specificity of aqueous tap are low, our results show that in a few cases it identified important organisms, otherwise missed by vitreous sampling alone. Culture of vitreous sample remains the gold standard for isolation of pathogen in bacterial endophthalmitis, but aqueous samples should also be obtained as an adjunct for the diagnosis.

Evaluation of the clinical usefulness of a chemiluminometric method for measuring creatine kinase MB

1990 ◽  
Vol 36 (10) ◽  
pp. 1809-1811 ◽  
Author(s):  
J R Pearson ◽  
F Carrea
Keyword(s):  
Creatine Kinase ◽  
Predictive Value ◽  
Characteristic Curve ◽  
High Sensitivity ◽  
High Specificity ◽  
Receiver Operator Characteristic Curve ◽  
Diagnostic Efficiency ◽  
Predictive Values ◽  
Creatine Kinase Mb ◽  
Rule Out

Abstract The use of creatine kinase isoenzymes (CK-MB) in the diagnosis of acute myocardial infarction (AMI) is well established. We evaluated the use of a new chemiluminometric method (CK-Ciba) for measuring CK-MB by calculating its sensitivity, specificity, positive and negative predictive values, and diagnostic efficiency for diagnosing AMI. We tested 633 samples from 229 patients within 4 h of receipt. The patients were divided into four groups: (1) patients who had an AMI, (2) patients who had AMI ruled out, (3) patients who had CK-MB measured for reasons other than to rule out AMI, and (4) patients who had only one sample drawn. Only patients in Groups 1 and 2 were used in the study. AMI was diagnosed by a cardiologist. The prevalence of AMI in our population was 0.18. A receiver-operator characteristic curve was used to establish optimal values for identifying AMI with the CK-Ciba results: CK-MB greater than or equal to 10 micrograms/L and a CK-MB index of greater than or equal to 3.0 (micrograms of CK-MB per U of CK x 100). Using these values, we calculated a sensitivity of 1.00, specificity of 0.97, positive predictive value of 0.87, negative predictive value of 1.00, and a diagnostic efficiency of 0.97. We conclude that the CK-Ciba method has high sensitivity, high specificity, and good predictive values for CK-MB and is appropriate to use to rule out AMI.

scholarly journals Evaluation of the Access Bio CareStartTM rapid SARS-CoV-2 antigen test in asymptomatic individuals tested at a community mass-testing program in Western Massachusetts

2021 ◽  
Author(s):  
Sara Suliman ◽  
Wilfredo R. Matias ◽  
Isabel R Fulcher ◽  
Francisco J. Molano ◽  
Shannon Collins ◽  
...  
Keyword(s):  
Point Of Care ◽  
Quantitative Polymerase Chain Reaction ◽  
High Specificity ◽  
Antigen Test ◽  
Predictive Values ◽  
Prevalence Estimates ◽  
Moderate Sensitivity ◽  
Testing Site ◽  
Asymptomatic Individuals ◽  
Sensitivity Specificity

Background: Point-of-care antigen-detecting rapid diagnostic tests (RDTs) for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) represent a scalable tool for SARS-CoV-2 infections surveillance. Data on their performance in real-world community settings is paramount for their implementation. Method: We evaluated the accuracy of CareStartTM COVID-19 Antigen test (CareStart) in a testing site in Holyoke, Massachusetts. We compared CareStart to a SARS-CoV-2 reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) reference, using anterior nasal swab samples. We calculated the sensitivity, specificity, and expected positive and negative predictive values at different SARS-CoV-2 prevalence estimates. Results: We performed 666 tests on 591 unique individuals. 573 (86%) were asymptomatic. There were 52 positive tests by RT-qPCR. The sensitivity of CareStart was 49.0% (95% Confidence Interval (CI): 34.8 - 63.4) and specificity was 99.5% (95% CI: 98.5 - 99.9). Among positive RT-qPCR tests, the median cycle threshold (Ct) was significantly lower in samples that tested positive on CareStart. Using a Ct ≤ 30 as a benchmark for positivity increased the sensitivity to 64.9% (95% CI: 47.5 - 79.8). Conclusions: CareStart has a high specificity and moderate sensitivity. The utility of RDTs, such as CareStart, in mass implementation should prioritize use cases in which a higher specificity is more important.

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