scholarly journals Cohen’s kappa statistics as a convenient means to identify accurate SARS-CoV-2 rapid antibody tests

Author(s):  
Harukazu Iseki

AbstractThere are many available rapid antibody tests, but the performance of such tests remains unclear. Moreover, it is difficult to compare among the various devices regarding their sensitivity & specificity.In order to compare the performance of such devices, we used Cohen’ kappa statistics to assess the level of agreement between RT-PCR and rapid antibody tests. In doing this study, we considered the term of validity after symptom-onset to compare two tests. It takes more than a week to produce antibodies in the body, and RT-PCR thus gives negative result in the convalescent period. On ELISA data from the literature kappa statistics was calculated as 1.0 beyond 10 days after symptom-onset. By taking these factors into consideration, we evaluated agreement with samples collected beyond 10 days of symptom-onset during the active period.We calculated the data from 9 devices, and the kappa statistics for English data were calculated as 0.64 on average. The same finding was 0.75 for Chinese data. These results corresponded with the values from sensitivity & specificity of their reports. Both reports had no details about the collection procedures. Kappa statistics might become even more accurate, if samples could be restricted to ones collected beyond 10 days. Regarding the data from our hospital’, the kappa statistics was 0.97 when restricted to samples collected beyond 10 days, which thus showed excellent agreement.By using kappa statistics, the performances of rapid antibody tests can be shown as one figure, so that their comparison becomes easy to carry out.Highlights▪Using kappa statistics, agreement between PCR and ELISA was perfect from the data beyond 10 days of symptom-onset.▪The results of kappa statistics corresponded with the values from sensitivity & specificity of the English and the Chinese literatures.▪Kappa statistics was calculated as 0.97 from the data beyond 10 days of symptom-onset, and sensitivity & specificity were 95.2% and 100% in our hospital.▪Kappa statistics is a convenient means to identify accurate rapid antibody tests.

2020 ◽  
Author(s):  
Rama Vancheeswaran ◽  
Merlin L Willcox ◽  
Beth Stuart ◽  
Matthew Knight ◽  
Hala Kandil ◽  
...  

AbstractObjectivesTo assess the real-world diagnostic accuracy of the Livzon point-of-care rapid test for antibodies to SARS-COV-2DesignProspective cohort studySettingDistrict general hospital in EnglandParticipants173 Patients and 224 hospital staff with a history of COVID-19 symptoms, and who underwent PCR and/or reference antibody testing for COVID-19.InterventionsThe Livzon point-of-care (POC) lateral flow immunoassay rapid antibody test (IgM and IgG) was conducted at least 7 days after onset of symptoms and compared to the composite reference standard of PCR for SARS-COV-2 plus reference laboratory testing for antibodies to SARS-COV-2. The SARS-CoV-2 RT-PCR was tested using the available molecular technology during the study time (PHE laboratories, GeneXpert® system Xpert, Xpress SARS-CoV-2 and Source bioscience laboratory). All molecular platforms/assays were PHE/NHSE approved. The reference antibody test was the Elecsys Anti-SARS-CoV-2 assay (Roche diagnostics GmBH).Main outcome measuresSensitivity and specificity of the rapid antibody testResultsThe reference antibody test was positive in 190/268 (70.9%) of participants with a history of symptoms suggestive of COVID-19; in the majority (n=312) the POC test was taken 35 days or more after onset of symptoms. The POC antibody test had an overall sensitivity of 90.1% (292/328, 95% CI 86.3 – 93.1) and specificity of 100% (68/68, 95% CI 94.7 - 100) for confirming prior SARS-CoV-2 infection when compared to the composite reference standard. Sensitivity was 97.8% (89/92, 95% CI 92.3% to 99.7%) in participants who had been admitted to hospital and 84.4% (124/147, 95% CI 77.5% to 89.8%) in those with milder illness who had never been seen in hospital.ConclusionsThe Livzon point-of-care antibody test had comparable sensitivity and specificity to the reference laboratory antibody test, so could be used in clinical settings to support decision-making about patients presenting with more than 10 days of symptoms of COVID-19.What is already known on this topic-Presence of IgG and IgM antibodies to SARS-COV-2 indicates that the person was infected at least 7 days previously and is usually no longer infectious.-Rapid point-of-care tests for antibodies to SARS-COV-2 are widely available, cheap and easy to use-Preliminary evaluations suggested that rapid antibody tests may have insufficient accuracy to be useful for testing individual patients.What this study adds-The rapid point-of-care test for antibodies to SARS-COV-2 was 90.1% sensitive and 100% specific compared to reference standards for prior infection with COVID-19.-This is comparable to reference antibody tests-The point-of-care test evaluated in this study could be used to support clinical decision-making in real time, for patients presenting with symptoms of possible COVID-19 with at least 10 days of symptoms.


PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258970
Author(s):  
Amanda Caplan ◽  
Kelly W. Bates ◽  
Carla Brioni ◽  
Aileen Santos ◽  
Linda M. Sabatini ◽  
...  

Background Studies of outpatients with mild or moderate COVID-19 are uncommon. We studied: 1) association of symptoms with reverse transcriptase polymerase chain reaction (RT-PCR) test results; and 2) association of initial RT-PCR cycle threshold (Ct) in relation to duration of RT-PCR positivity in outpatients with mild or moderate COVID-19. Methods This was a cohort study of outpatients with confirmed COVID-19 and at least one symptom. Participants had repeat nasopharyngeal swabs and symptom checklists every 3–5 days until two consecutive RT-PCR tests were negative. RT-PCR tests were used to assess viral load. Antibody tests for COVID-19 were performed at 2 weeks, 4 weeks, and 8 weeks after symptom onset. Results Twenty-five patients (nine females) were enrolled, ranging in age from 19–58 (median age 28 years). All patients reported at least one symptom, with a median of six symptoms per patient. Symptoms persisted for 6–67 days (median duration 18 days). In all 25 patients, blood samples collected a median of 13 days after symptom onset were positive for SARS-CoV-2 antibodies in 15 (60%). After a median of 28 days following symptom onset, 23/23 patients with available samples tested positive for antibodies. The longest duration of positive RT-PCR test was 49 days from first positive PCR test (Mean = 27.4, SD = 12.5, Median = 24). Initial Ct was significantly associated with longer duration (β = -1.3, SE = 0.3, p<0.01 per 1 cycle higher) of RT-PCR positivity. Conclusions In mildly or moderately ill COVID-19 outpatients, RT-PCT tests remained positive for as long as 49 days and test positivity and symptom duration correlated with initial viral load.


2020 ◽  
Vol 6 (Khusus) ◽  
pp. 47
Author(s):  
Anita Suswanti Agustina ◽  
Rizana Fajrunni'mah

COVID-19 is caused by SARS-CoV-2, which can spread rapidly from human to human. There are several laboratory tests to detect COVID-19, including the Reverse Transcription-Polymerase Chain Reaction (RT-PCR) method and a rapid test antibody test to detect antibody reactions to SARS-CoV-2. Both methods have advantages and disadvantages of each, while the literature study comparing the two methods is currently limited. The type of research used is library research. Research materials have been collected from various journals, books, and guidelines, in line with the research topic, to obtain 24 library sources. The results of the literature study indicate that the target genes that can be used to detect COVID-19 RT-PCR methods include the N, E, RdRp, and ORF1a/b genes. The sensitivity of rapid antibody tests is known to range from 68−89%, while the specificity of rapid antibody tests ranges from 91−100%. RT-PCR has the advantage of being able to detect low-concentration antigens, but RT-PCR has weaknesses such as requiring expensive equipment and inspection fees, specially trained laboratory personnel, long working time, and high risk of exposure. Rapid antibody testing has advantages, including ease of sampling, lower testing costs, reduced risk of exposure to officers, does not require special equipment and space, but has the potential for cross-reactivity with other coronaviruses. Both the RT-PCR method and the rapid antibody test have their advantages and disadvantages, but rapid antibody testing with RT-PCR can improve the diagnosis of COVID-19. The results of this literature study are expected to be continued as a basis for further research on RT-PCR examination and antibody rapid test for COVID-19 detection in Indonesia, accompanied by information on onset time and time-testing with a large sample of research.


Author(s):  
Yoshifumi Uwamino ◽  
Masatoshi Wakui ◽  
Wataru Aoki ◽  
Toshinobu Kurafuji ◽  
Emmy Yanagita ◽  
...  

Background: The usability of laboratory tests related to SARS-CoV-2 is critically important for the world undergoing the COVID-19 pandemic. The present study aimed to assess diagnostic usability of rapid tests for detection of antibody against SARS-CoV-2 through comparison of their results with results of RT-PCR test for detection of SARS-CoV-2 genomic RNA and with results of a quantitative test for antibody detection. Methods: Serum samples were collected from eighteen patients undergoing RT-PCR testing for SARS-CoV-2. Twelve patients were RT-PCR positive while six were negative. A quantitative test based on chemiluminescent immunoassay and three rapid tests based on immunochromatography were performed to detect anti-SARS-CoV-2 IgG and IgM. Results: All the antibody tests exhibited poor sensitivity at the timing of initial RT-PCR diagnosis. IgG responses occurring prior to or simultaneously with IgM responses were observed through not only the quantitative test but also the three rapid tests. Based on concordance with the quantitative test results, the large variance among the three rapid tests was revealed. Conclusions: All antibody tests were unsatisfactory to replace RT-PCR for early diagnosis of COVID-19. Rapid antibody tests as well as a quantitative antibody test were useful in assessment of immune responses in COVID-19. The obvious variance among the three rapid tests suggested limited accuracy and difficult standardization. Diagnostic usability of rapid antibody tests for COVID-19 should be investigated rigorously.


2021 ◽  
Vol 8 (7) ◽  
pp. 117
Author(s):  
Giovanni Cilia ◽  
Laura Zavatta ◽  
Rosa Ranalli ◽  
Antonio Nanetti ◽  
Laura Bortolotti

The deformed wing virus (DWV) is one of the most common honey bee pathogens. The virus may also be detected in other insect species, including Bombus terrestris adults from wild and managed colonies. In this study, individuals of all stages, castes, and sexes were sampled from three commercial colonies exhibiting the presence of deformed workers and analysed for the presence of DWV. Adults (deformed individuals, gynes, workers, males) had their head exscinded from the rest of the body and the two parts were analysed separately by RT-PCR. Juvenile stages (pupae, larvae, and eggs) were analysed undissected. All individuals tested positive for replicative DWV, but deformed adults showed a higher number of copies compared to asymptomatic individuals. Moreover, they showed viral infection in their heads. Sequence analysis indicated that the obtained DWV amplicons belonged to a strain isolated in the United Kingdom. Further studies are needed to characterize the specific DWV target organs in the bumblebees. The result of this study indicates the evidence of DWV infection in B. terrestris specimens that could cause wing deformities, suggesting a relationship between the deformities and the virus localization in the head. Further studies are needed to define if a specific organ could be a target in symptomatic bumblebees.


Trials ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Anurag Srivastava ◽  
Manickavasagam Rengaraju ◽  
Saurabh Srivastava ◽  
Vimal Narayan ◽  
Vivek Gupta ◽  
...  

Abstract Objectives The primary objectives of the study are to determine the effectiveness of the Kaba Sura Kudineer (KSK) & Nilavembu Kudineer (NVK) along with standard Allopathy Treatment to compared with Placebo (Decaffeinated Tea) with standard Allopathy Treatment in the management of Symptomatic COVID 19 patients and also in reduction of Hospital Stay Time & Changes in Immunological (IL6) and Bio Chemical Markers (Ferritin, CRP, D-Dimer and LDH). The secondary objectives are to evaluate the safety of the trial medicines and their effects in the reduce the risks of the disease. In addition, to document the profile of Symptomatic COVID 19 patients as per Siddha Principles. Trial Design A Double Blinded, Three arm, Single Centre, Placebo Controlled, Exploratory and comparative Randomized Controlled Trial Participants Patients who were admitted to the COVID Care Centre at Govt. Institute of Medical Sciences. Noida in India will be recruited. These will be patients with Mild and Moderate symptoms with laboratory confirmed COVID 19 (RT – PCR Tested Positive) aged 18-65, willing and consenting to participate. Intervention and comparator Arm I: Decaffeinated Tea (Placebo – similar in taste and appearance to the other Two Decoctions), 60 Ml Morning and Night after Food, along with standard Allopathy Treatment for 10 days. Arm II: Nilavembu Kudineer (The Siddha Medicines which is used as a standard Anti-Viral drug for the past Pandemics by Siddha Physicians) 60 Ml Morning and Night after Food, along with standard Allopathy Treatment for 10 days. Arm III: Kaba Sura Kudineer (The Siddha Medicine which is proposed to be used as a Treatment for COVID 19 based on Siddha Literature) 60 Ml Morning and Night after Food, along with standard Allopathy Treatment for 10 days. The investigational drugs are registered products under the Govt.of India and bought from GMP Certified Manufacturing Units. Main Outcomes Primary outcomes: Reduction in Viral load of SARS-CoV-2 at the end of treatment (10 days). 2. Time taken to convert Patient from symptomatic to Asymptomatic based on Reduction in clinical symptoms (10 days). 3. Effect of drugs inflammatory markers (IL6,) at the end of treatment (10 days). 4. Reduction in hospital stay time (20 days follow up). (Based on RT PCR CT Value 3rd, 6th if needed 10th day). (Based on IL 6 Value needed 10th day or IL6 value on turning negative. (entry level/exit level). Secondary outcomes (10 days): Reduction in use of Intensive Supportive Care. 2. Reduction in incidence of complications (Acute Respiratory Distress Syndrome, other systemic complications). 3. MuLBSTA score for viral pneumonia (multinodular infiltration, hypo-lymphocytosis, bacterial co infection, Total Leucocyte Count (TLC ≤ 0.8 x 109/L), smoking history, hyper-tension and age) score. 4. Laboratory markers (Haematological & Biochemical Markers). 5. Adverse events/effects Siddha-based measurements. 6. Siddha Udaliyal assessment by using Yakkai Ilakkanam (YI) Tool to diagnose body condition for covid-19 patients. Randomisation The assignment of the participants into 3 Groups will be allocated in 1:1:1 Ratio through randomization Blocks in Microsoft Excel by a Statistician who is not involved in the study. The allocation scheme will be made by another statistician by using a closed envelope after the assessment of eligibility and Informed consent procedures. The groups will be balanced for age and sex with 3:1 Ratio in each group for mild: severe COVID-19 symptoms. Blinding The Study is Double Blinded. Participants and Investigators were blinded. Numbers to be randomized (Sample size) Sample size could not be calculated, Since there are no prior trials on KSK and NVK as a comparative trial. In addition, there are no prior trials on KSK and NVK in this region. A total Number of 120 Patients, 40 each in 3 groups will be recruited in 1:1:1 Ratio. Trial Status Protocol Number : SCRUND GIMS Noida Study 1,Version: 2.0 Protocol Date : 20.08.2020 The recruitment period is completed for the trial. The Trial started its recruitment on 22.8.2020. We anticipate study including data analysis will finish in January 2021. This is to state that it was a late submission from authors for publication of the protocol to the BMC, after enrolment in the study was over. Trial Registration The trial protocol was registered with CTRI (Clinical Trial Registry of India) and number is CTRI/2020/08/027286 on 21.08.2020 Full Protocol The full Protocol is attached as an additional file, Accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated. This letter serves as a summary of the key elements of the full protocol. The Study protocol has been reported in accordance with the SPIRIT guidelines.


Intervirology ◽  
2021 ◽  
pp. 1-6
Author(s):  
Salman Khan ◽  
Syed Asad Ali Shah ◽  
Syed Muhammad Jamal

<b><i>Background:</i></b> Foot-and-mouth disease (FMD) is an infectious and highly contagious disease of cloven-hoofed domestic and wild animals, causing heavy economic losses to the livestock industry. Rapid and reliable diagnosis of the disease is essential for the implementation of effective control measures. This study compared sandwich enzyme-linked immunosorbent assay (S-ELISA) and conventional reverse transcription polymerase chain reaction (RT-PCR) for the diagnosis of FMD. <b><i>Methods:</i></b> A total of 60 epithelial samples from suspected cases of FMD were tested using both S-ELISA and RT-PCR assays. The level of agreement between the assays was assessed by calculating the Kappa value. <b><i>Results:</i></b> S-ELISA detected 38 (63%) samples positive for FMD virus (FMDV). Being predominant, serotype O was detected in 22 (57.9%) of the total samples tested positive, whereas 9 (23.7%) and 7 (18.4%) samples were found positive for serotypes A and Asia-1, respectively. RT-PCR detected viral genome in 51 (85%) of the samples using pan-FMDV primers set, 1F/1R. Thirty-six samples were found positive and 7 negative by both the tests. The level of agreement between the tests was assessed by calculating the Kappa value, which was found to be fair (Kappa value = 0.303 and 95% CI = 0.089; 0.517) and significant (<i>p</i> = 0.009). However, 2 samples, which were found positive on S-ELISA tested negative on RT-PCR. This may be attributed to the presence of nucleotide mismatch(es) in the primer-binding sites that may have resulted in failure of amplification of the viral genome. The serotype-specific RT-PCR assays not only confirmed serotyping results of S-ELISA but were also able to establish serotype in 9 S-ELISA-negative but pan-FMDV RT-PCR-positive samples. <b><i>Conclusions:</i></b> The RT-PCR assay contributes significantly to establishing a quick, sensitive, and definitive diagnosis of FMD in resource-constrained countries. Samples giving negative results in S-ELISA should be tested in RT-PCR for the disease detection and virus typing.


Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Edith Matesic

Background: Stroke patients initially experience dysphagia approximately 42-76% of the time, putting them at high risk for developing aspiration pneumonia and increasing the risk of death threefold in the first 30 days following onset of the condition. Interventions to identify risk for aspiration pneumonia are key to reducing mortality in hospitalized patients. However, no generally recognized bedside aspiration screen exists, and few have been rigorously tested. The Edith-Huhn-Matesic Bedside Aspiration Screen (EHMBAS) TM was developed as an evidence-based RN bedside aspiration screening protocol. Purpose: This study analyzed the sensitivity and inter-rater reliability of EHMBAS TM , assessed the efficacy of training methods, evaluated patient feedback, and looked at the impact of organizational learning. Methods: RNs were trained to apply the EHMBAS TM . An evaluation study assessed the sensitivity, specificity and predictability of the screen to detect aspiration in the stroke population study group. Cohen’s Kappa statistics was applied to test inter-rater reliability. Pre- and post-implementation Likert surveys examined patient and staff satisfaction on the education plan and screening process, respectively. Lastly, an analysis of organizational learning examined whether changes enhanced adherence to screening requirements. Results: Results showed that the EHMBAS TM demonstrated strong validity (94% sensitivity) and high inter-rater reliability (Kappa = .92, p<.001). Pre- and post- staff training survey results demonstrated a significant positive change in knowledge gained, feelings of preparedness, and satisfaction with teaching methods. Further, 92.3% of patients surveyed had positive screening experiences. The hospital received Silver recognition from The American Heart Association for following stroke treatment guidelines 85% of the time for at least 12 months, demonstrating the positive impact of the protocol on organizational change. Conclusions: This study contributes to the body of work aimed at establishing a reliable evidence-based, bedside aspiration screen. Patient safety is enhanced, because screen results help determine when patients can safely receive medication and nutrition by mouth.


2014 ◽  
Vol 17 (3) ◽  
pp. 747-760 ◽  
Author(s):  
Carla Fernandez dos Santos ◽  
Inês Rugani Ribeiro de Castro ◽  
Letícia de Oliveira Cardoso ◽  
Letícia Ferreira Tavares

The aim of the study was to examine the correlation among different indicators of body image; between each one of these and nutritional status; and the association of these indicators with the Body Mass Index (BMI) of adolescents. A random sample of 152 students from public and private schools in the city of Rio de Janeiro, Brazil, was studied. On four occasions, two silhouette scales and two questions regarding the opinion of the student about his/her body and weight were applied and weight and height were measured. The BMI was examined both as a continuous and as a categorical variable. The agreement between the variables was analyzed using the quadratic weighted Kappa statistics. The association between body image variables and BMI was examined by the comparison among median, mean, standard deviation and 95% confidence interval of BMI for each category of the body image variables. In general, the correlation among the body image variables ranged from reasonable to good; between these and the variable nutritional status, correlation ranged from regular to reasonable. Best results were observed among boys and students from private schools. All body image variables showed good discriminatory power for BMI, when it was analyzed as a continuous variable, even when controlling for potential confounders. The question about body seems to be better than that about weight to compose the questionnaire of a surveillance system for risk and protective factors for adolescent health.


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