scholarly journals 427. Variation in SARS-CoV-2 molecular diagnostic test performance in symptomatic versus asymptomatic populations

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S280-S280
Author(s):  
Sanjat Kanjilal ◽  
Meghan Baker ◽  
Ann E Woolley ◽  
Chanu Rhee ◽  
Athena K Petrides ◽  
...  
Keyword(s):  
Test Performance ◽  
Molecular Diagnostic ◽  
Indirect Measure ◽  
Viral Loads ◽  
Ct Value ◽  
Asymptomatic Patients ◽  
Diagnostic Test Performance ◽  
Asymptomatic Individuals ◽  
Molecular Diagnostic Test ◽  
The Impact

Abstract Background Growing recognition of the importance of asymptomatic and pre-symptomatic transmission for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has led to a substantial expansion of testing from symptomatic to asymptomatic patients, and particularly those with risk factors for infection. Viral burden in asymptomatic individuals can differ from symptomatic patients, which can impact test performance. We therefore evaluated the impact of expanded testing indications upon the sensitivity and specificity of molecular diagnostic assays for SARS-CoV-2. Methods We performed a retrospective review of laboratory results from 5,122 emergency room patients and inpatients tested for SARS-CoV-2 between 05/03/2020 and 06/13/2020 using the Hologic Panther Fusion and the Cepheid Xpert assays at the Brigham & Women’s Hospital in Boston, MA. Descriptive analyses were performed for trends in testing volume, rates of positivity and cycle thresholds (Cts) over time based on symptom status. We calculated the proportion of new diagnoses made on a patient’s first test as an indirect measure of sensitivity. We calculated the proportion of first tests that are positive with a Ct value < 35 as an indirect measure of specificity. Results The overall rate of positivity over the study period was 8.7% (599/7,510 tests; 440/4,795 people) and declined by 1.8% (95% CI -2.2% - -1.4%, P< 0.0001) each week. Relative to tests in symptomatic people, the asymptomatic population had a higher mean Ct value (35.1 vs 32.3; P < 0.0001). Ct values increased by 0.7 (95% CI -0.1 - +1.4, P=0.07) and 0.8 (95% CI +0.3 - +1.4; p=0.01), sensitivity declined by 4% (95% CI -9% - +1%, P=0.08) and 12% (95% CI -20% - -5%, P-0.01) and specificity declined by 8% (95% CI -3% to 20%; P=0.13) and 9% (95% CI 7% - 11%; P=0.0002), over the time period of the study for asymptomatic and symptomatic patients, respectively. Figure 1: Trends in Ct values by symptoms Figure 2: Trends in diagnosis by first versus second test by symptoms Figure 3: Trends in proportion of people with their first test having Ct < 35 by symptoms Conclusion We show that the proportion of patients with low SARS-CoV-2 viral loads has increased as testing has expanded to the asymptomatic population and as transmission wanes in the community. This negatively impacts the performance of molecular assays by increasing the risk of false negatives and the detection of non-viable virus. Decision algorithms based on molecular assay results may need re-evaluation in light of these dynamics. Disclosures All Authors: No reported disclosures

scholarly journals Differential Kinetics of Cycle Threshold Values during Admission by Symptoms among Patients with Mild COVID-19: A Prospective Cohort Study

2021 ◽  
Vol 18 (15) ◽  
pp. 8181
Author(s):  
Teppei Sakano ◽  
Mitsuyoshi Urashima ◽  
Hiroyuki Takao ◽  
Kohei Takeshita ◽  
Hiroe Kobashi ◽  
...  
Keyword(s):  
Cohort Study ◽  
Viral Load ◽  
Prospective Cohort Study ◽  
Prospective Cohort ◽  
Polymerase Chain Reaction Test ◽  
Cycle Threshold ◽  
Viral Loads ◽  
Asymptomatic Patients ◽  
Asymptomatic Individuals ◽  
Chain Reaction Test

In the coronavirus disease 2019 (COVID-19) pandemic, more than half of the cases of transmission may occur via asymptomatic individuals, which makes it difficult to contain. However, whether viral load in the throat during admission is different between asymptomatic and symptomatic patients is not well known. By conducting a prospective cohort study of patients with asymptomatic or mild COVID-19, cycle threshold (Ct) values of the polymerase chain reaction test for COVID-19 were examined every other day during admission. The Ct values during admission increased more steadily in symptomatic patients and febrile patients than in asymptomatic patients, with significance (p = 0.01 and p = 0.004, respectively), although the Ct values as a whole were not significantly different between the two groups. Moreover, the Ct values as a whole were higher in patients with dysosmia/dysgeusia than in those without it (p = 0.02), whereas they were lower in patients with a headache than those without (p = 0.01). Patients who were IgG-positive at discharge maintained higher Ct values, e.g., more than 35, during admission than those with IgG-negative (p = 0.03). Assuming that viral load and Ct values are negatively associated, the viral loads as a whole and their changes by time may be different by symptoms and immune reaction, i.e., IgG-positive at discharge.

scholarly journals Comparison of Quidel Sofia SARS FIA Test to Hologic Aptima SARS-CoV-2 TMA Test for Diagnosis of COVID-19 in Symptomatic Outpatients

2020 ◽  
Author(s):  
Eric T. Beck ◽  
Wendy Paar ◽  
Lara Fojut ◽  
Jordan Serwe ◽  
Renee R. Jahnke
Keyword(s):  
Symptom Onset ◽  
Care Center ◽  
Urgent Care ◽  
Molecular Diagnostic ◽  
Nasopharyngeal Swab ◽  
Urgent Care Center ◽  
Ct Value ◽  
High Prevalence ◽  
Nasal Swabs ◽  
Molecular Diagnostic Test

The Quidel Sofia SARS FIA test (SOFIA) is a rapid antigen immunoassay for detection of SARS-CoV-2 viral proteins from nasal or nasopharyngeal swab specimens. The purpose of this study was to compare the results of the SOFIA test to the Hologic Aptima SARS-CoV-2 TMA test (APTIMA TMA), a high-throughput molecular diagnostic test that uses transcription mediated amplification for detection of SARS-CoV-2 nucleic acid from upper respiratory specimens. Three hundred and 40-seven symptomatic patients, from an urgent care center in an area with a high prevalence of SARS-CoV-2 infections, were tested in parallel using nasal swabs on the SOFIA test and nasopharyngeal swabs on the APTIMA TMA test. The SOFIA test demonstrated an 82.0% positive percent agreement (PPA) compared to the APTIMA TMA test for symptomatic patients tested ≤ 5 days from symptom onset and a 54.5% PPA for symptomatic patients > 5 days from symptom onset. The Cepheid Xpert Xpress SARS-CoV-2 RT-PCR test was used to determine the cycle threshold (Ct) value from any specimens that were discrepant between the SOFIA and APTIMA TMA tests. Using a Ct value of ≤ 35 as a surrogate for SARS-CoV-2 culture positivity, we estimate that the SOFIA test detected 87.2% of symptomatic patients tested ≤ 5 days from symptom onset that were likely to be culture positive.

scholarly journals Major impact of left auricular cardiopathy when associated to supraventricular ectopy?

2021 ◽  
Vol 10 (Supplement_1) ◽  
Author(s):  
C Marques Pires ◽  
AR Silva ◽  
P Medeiros ◽  
I Campos ◽  
C Oliveira ◽  
...  
Keyword(s):  
Diagnostic Test ◽  
Test Performance ◽  
Left Atrial ◽  
Cox Regression ◽  
Composite Endpoint ◽  
Embolic Stroke ◽  
P Wave ◽  
Stroke Recurrence ◽  
Diagnostic Test Performance ◽  
The Impact

Abstract Funding Acknowledgements Type of funding sources: None. INTRODUCTION Left atrial cardiopathy (LAC) is an independent predictor of atrial fibrillation (FA) and embolic stroke. It is more frequent in patients with embolic stroke of undetermined source (ESUS) than in non-embolic strokes. The current definition doesn’t include supraventricular ectopy. AIM The aim of this work was to describe the importance of LAC in ESUS and to study the impact of adding the number of atrial premature complexes per hour (APC/h) to LAC criteria. METHODS Retrospective analysis of 123 ESUS patients (pts) admitted to Neurology service from 2014 to 2019. LAC was defined according to two criteria (LAC2: severe left atrial enlargement or p-wave terminal force in lead V1 [PTFV1] >5000 µV*ms) or 3 criteria (LAC3: additionally, >30 APC/h). Survival analysis for the occurrence of AF, stroke recurrence and death according to LAC2 and LAC3. Diagnostic test performance analysis for each criterion with ROC curves. RESULTS 43 (35%) of the ESUS pts had LAC2. Pts with LAC2 (35.0%) were older (p = 0.007), more frequently had hypertension (p = 0.004) and lower total cholesterol levels (p = 0.044) than patients without LAC2. The incidence of AF (median follow-up 21 months, IQR = 9-35) was higher both in LAC2 (p = 0.038) and LAC3 (p = 0.001). There were no differences in stroke recurrence or death between patients with or without LAC2 or 3. Among the 3 atrial dysfunction criteria included in LAC3 definition, the number of APC/h was associated with a higher area under the curve for the occurrence of AF (AUC = 0.822). Cox regression revealed that PTFV1 > 5000 µV·ms (HR = 5.12, IC95%=1.28-20.56, p = 0.021) and >30 APC/h (HR = 13.02, IC95%=3.57-47.56) were independent predictors of AF. In addition, the single predictor of the composite endpoint (occurrence of AF, stroke recurrence and death) was >30 APC/h (HR = 5.2, p < 0,001). CONCLUSION In ESUS pts, the subgroup with LAC2 had different clinical characteristics and a higher AF incidence. APC/h were also independently associated with AF incidence and had better diagnostic test performance than the other criteria. In sum, APC/h inclusion as a diagnostic criterion for LAC should be considered and may help in a better therapeutic approach.

scholarly journals Impact of Pool Testing in Detection of Asymptomatic Patients with COVID-19

2020 ◽  
Vol 52 (1) ◽  
pp. e15-e16 ◽  
Author(s):  
David L Smalley ◽  
Patricia M Cisarik ◽  
James Grantham ◽  
William Cloud ◽  
R Brock Neil ◽  
...  
Keyword(s):  
Single Patient ◽  
Rt Pcr ◽  
Detection Capability ◽  
Chain Reaction ◽  
Asymptomatic Patients ◽  
Alternative Approaches ◽  
Polymerase Chain ◽  
Asymptomatic Individuals ◽  
Low Prevalence ◽  
The Impact

Abstract Objective During the current pandemic, COVID-19 has been detected in patients using real-time reverse transcriptase-polymerase chain reaction (RT-PCR) that confirms the presence of SARS-CoV-2 RNA. The demand for increased testing, particularly for asymptomatic individuals required alternative approaches to single-patient RT-PCR testing, such as pooling. Methods This study explored the impact of dilution on the detectability of SARS-CoV-2 in asymptomatic patients using RT-PCR and demonstrated that pooling can be effective in low prevalence populations. Results The RT-PCR results for the 3:1, 5:1, and 7:1 aliquot samples showed little differences in CT values, confirming detection capability at these dilutions. Conclusion Based on the results of the present study, a pooled approach with up to 5:1 sample aliquots and using the current RT-PCR methodology likely will detect SARS CoV2 RNA among asymptomatic patients.

The Impact of Patient Characteristics on Diagnostic Test Performance

Small Methods ◽  
2022 ◽  
pp. 2101233
Author(s):  
Hannah N. Kozlowski ◽  
Shrey Sindhwani ◽  
Warren C. W. Chan
Keyword(s):  
Diagnostic Test ◽  
Test Performance ◽  
Patient Characteristics ◽  
Diagnostic Test Performance ◽  
The Impact

scholarly journals An Extended Laboratory Validation Study and Comparative Performance Evaluation of the Abbott ID NOW™ COVID-19 Assay in a Coastal California Tertiary Care Medical Center

2020 ◽  
Author(s):  
Stewart Comer ◽  
David Fisk
Keyword(s):  
Test Performance ◽  
Medical Center ◽  
Point Of Care ◽  
Tertiary Care ◽  
Molecular Diagnostic ◽  
Patient Classification ◽  
Optimal Test ◽  
Comparative Performance ◽  
Tertiary Care Medical Center ◽  
Molecular Diagnostic Test

AbstractThe Abbott ID NOW™ COVID-19 assay is a rapid molecular diagnostic test particularly designed for on-site, rapid turnaround point of care (POC) testing. The utilization of rapid diagnostic tests is integral to optimizing workflow within the hospital and/or procedural-based clinics. The capability to provide both rapid disposition and correct patient classification during this COVID-19 pandemic is critically important with broad infection control implications for both patients and healthcare staff. A tightly controlled, extended laboratory validation was performed at our medical center to determine the negative test agreement of the Abbott ID NOW™ compared with the BD MAX™ analyzer, a laboratory-based, two target, molecular analyzer with a sensitive cycle threshold (Ct) positive cutoff value of ≤ 42. There was strict adoption of the procedures listed in the Abbott ID NOW™ Instruction for Use (IFU)1 insert delineating preferred practices for “optimal test performance.” Under these conditions, our institution demonstrated a significant negative percent agreement with 116 out of 117 patients correlating, which equates to a 99.1% concordance similar to a recently reported correlation study2.

scholarly journals Limited Sensitivity of a Rapid SARS-CoV-2 Antigen Detection Assay for Surveillance of Asymptomatic Individuals in Thailand

2021 ◽  
Author(s):  
Anek Mungomklang ◽  
Nichapa Trichaisri ◽  
Jittima Jirachewee ◽  
Jaravee Sukprasert ◽  
Warut Tulalamba ◽  
...  
Keyword(s):  
Test Performance ◽  
National Level ◽  
Rapid Test ◽  
Control Program ◽  
Threshold Value ◽  
Antigen Test ◽  
Viral Loads ◽  
Global Pandemic ◽  
Detection Assay ◽  
Asymptomatic Individuals

COVID-19 is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is a global pandemic. Therefore, rapid and accurate tests for SARS-CoV-2 screening are urgently needed to expedite disease prevention and control especially in community transmission. Since late December 2020, Thailand has faced a new wave of COVID-19 outbreaks. The Thai National Disease Control program at the Ministry of Public Health has identified suitable measure for mass screening. A SARS-CoV-2 antigen-based assay is a surveillance option for active cases. Here, we evaluated the feasibility and test performance of a rapid SARS-CoV-2 antigen test during our field activities in 1,100 asymptomatic individuals in Samut Sakhon, Thailand, during the second wave COVID-19 outbreak (December 26–30, 2020). The results showed that the rapid antigen test had a sensitivity of 47.97% (95% CI: 36.10–59.96%) and a specificity of 99.71% (95% CI: 99.15–99.94%) versus standard reverse-transcriptase polymerase chain reaction. The rapid test performed better in cases with higher viral loads determined by the cycle threshold value. In real-world setting, the test performance can be compromised by several factors including viral loads, logistic chains, temperature, technical expertise of the operators, validity, and accuracy of the testing itself. Our study highlights a prerequisite for reevaluation of any given testing before implementing it at the national level.

scholarly journals 458. Molecular SARS-CoV-2 Testing During the COVID-19 Outbreak: Experiences of a Hospital in Southeast Michigan, USA

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S296-S297
Author(s):  
Trini A Mathew ◽  
Jonathan Hopkins ◽  
Diane Kamerer ◽  
Shagufta N Ali ◽  
Daniel Ortiz ◽  
...  
Keyword(s):  
Clinical Features ◽  
Diagnostic Testing ◽  
Beaumont Hospital ◽  
High Capacity ◽  
Turnaround Time ◽  
Molecular Diagnostic ◽  
The Novel ◽  
Repeat Testing ◽  
Asymptomatic Patients ◽  
Novel Coronavirus

Abstract Background The novel Coronavirus SARS CoV-2 (COVID-19) outbreak was complicated by the lack of diagnostic testing kits. In early March 2020, leadership at Beaumont Hospital, Royal Oak Michigan (Beaumont) identified the need to develop high capacity testing modalities with appropriate sensitivity and specificity and rapid turnaround time. We describe the molecular diagnostic testing experience since initial rollout on March 16, 2020 at Beaumont, and results of repeat testing during the peak of the COVID-19 pandemic in MI. Methods Beaumont is an 1100 bed hospital in Southeast MI. In March, testing was initially performed with the EUA Luminex NxTAG CoV Extended Panel until March 28, 2020 when testing was converted to the EUA Cepheid Xpert Xpress SARS-CoV-2 for quicker turnaround times. Each assay was validated with a combination of patient samples and contrived specimens. Results During the initial week of testing there was > 20 % specimen positivity. As the prevalence grew the positivity rate reached 68% by the end of March (Figure 1). Many state and hospital initiatives were implemented during the outbreak, including social distancing and screening of asymptomatic patients to increase case-finding and prevent transmission. We also adopted a process for clinical review of symptomatic patients who initially tested negative for SARS-CoV-2 by a group of infectious disease physicians (Figure 2). This process was expanded to include other trained clinicians who were redeployed from other departments in the hospital. Repeat testing was performed to allow consideration of discontinuation of isolation precautions. During the surge of community cases from March 16 to April 30, 2020, we identified patients with negative PCR tests who subsequently had repeat testing based on clinical evaluation, with 7.1% (39/551) returning positive for SARS- CoV2. Of the patients who expired due to COVID-19 during this period, 4.3% (9/206) initially tested negative before ultimately testing positive. Figure 1 BH RO testing Epicurve Figure 2: Screening tool for repeat COVID19 testing and precautions Conclusion Many state and hospital initiatives helped us flatten the curve for COVID-19. Our hospital testing experience indicate that repeat testing may be warranted for those patients with clinical features suggestive of COVID-19. We will further analyze these cases and clinical features that prompted repeat testing. Disclosures All Authors: No reported disclosures

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