Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

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Dr Mohan Z Mani

"Thank you very much for having published my article in record time.I would like to compliment you and your entire staff for your promptness, courtesy, and willingness to be customer friendly, which is quite unusual.I was given your reference by a colleague in pathology,and was able to directly phone your editorial office for clarifications.I would particularly like to thank the publication managers and the Assistant Editor who were following up my article. I would also like to thank you for adjusting the money I paid initially into payment for my modified article,and refunding the balance.
I wish all success to your journal and look forward to sending you any suitable similar article in future"



Dr Mohan Z Mani,
Professor & Head,
Department of Dermatolgy,
Believers Church Medical College,
Thiruvalla, Kerala
On Sep 2018




Prof. Somashekhar Nimbalkar

"Over the last few years, we have published our research regularly in Journal of Clinical and Diagnostic Research. Having published in more than 20 high impact journals over the last five years including several high impact ones and reviewing articles for even more journals across my fields of interest, we value our published work in JCDR for their high standards in publishing scientific articles. The ease of submission, the rapid reviews in under a month, the high quality of their reviewers and keen attention to the final process of proofs and publication, ensure that there are no mistakes in the final article. We have been asked clarifications on several occasions and have been happy to provide them and it exemplifies the commitment to quality of the team at JCDR."



Prof. Somashekhar Nimbalkar
Head, Department of Pediatrics, Pramukhswami Medical College, Karamsad
Chairman, Research Group, Charutar Arogya Mandal, Karamsad
National Joint Coordinator - Advanced IAP NNF NRP Program
Ex-Member, Governing Body, National Neonatology Forum, New Delhi
Ex-President - National Neonatology Forum Gujarat State Chapter
Department of Pediatrics, Pramukhswami Medical College, Karamsad, Anand, Gujarat.
On Sep 2018




Dr. Kalyani R

"Journal of Clinical and Diagnostic Research is at present a well-known Indian originated scientific journal which started with a humble beginning. I have been associated with this journal since many years. I appreciate the Editor, Dr. Hemant Jain, for his constant effort in bringing up this journal to the present status right from the scratch. The journal is multidisciplinary. It encourages in publishing the scientific articles from postgraduates and also the beginners who start their career. At the same time the journal also caters for the high quality articles from specialty and super-specialty researchers. Hence it provides a platform for the scientist and researchers to publish. The other aspect of it is, the readers get the information regarding the most recent developments in science which can be used for teaching, research, treating patients and to some extent take preventive measures against certain diseases. The journal is contributing immensely to the society at national and international level."



Dr Kalyani R
Professor and Head
Department of Pathology
Sri Devaraj Urs Medical College
Sri Devaraj Urs Academy of Higher Education and Research , Kolar, Karnataka
On Sep 2018




Dr. Saumya Navit

"As a peer-reviewed journal, the Journal of Clinical and Diagnostic Research provides an opportunity to researchers, scientists and budding professionals to explore the developments in the field of medicine and dentistry and their varied specialities, thus extending our view on biological diversities of living species in relation to medicine.
‘Knowledge is treasure of a wise man.’ The free access of this journal provides an immense scope of learning for the both the old and the young in field of medicine and dentistry as well. The multidisciplinary nature of the journal makes it a better platform to absorb all that is being researched and developed. The publication process is systematic and professional. Online submission, publication and peer reviewing makes it a user-friendly journal.
As an experienced dentist and an academician, I proudly recommend this journal to the dental fraternity as a good quality open access platform for rapid communication of their cutting-edge research progress and discovery.
I wish JCDR a great success and I hope that journal will soar higher with the passing time."



Dr Saumya Navit
Professor and Head
Department of Pediatric Dentistry
Saraswati Dental College
Lucknow
On Sep 2018




Dr. Arunava Biswas

"My sincere attachment with JCDR as an author as well as reviewer is a learning experience . Their systematic approach in publication of article in various categories is really praiseworthy.
Their prompt and timely response to review's query and the manner in which they have set the reviewing process helps in extracting the best possible scientific writings for publication.
It's a honour and pride to be a part of the JCDR team. My very best wishes to JCDR and hope it will sparkle up above the sky as a high indexed journal in near future."



Dr. Arunava Biswas
MD, DM (Clinical Pharmacology)
Assistant Professor
Department of Pharmacology
Calcutta National Medical College & Hospital , Kolkata




Dr. C.S. Ramesh Babu
" Journal of Clinical and Diagnostic Research (JCDR) is a multi-specialty medical and dental journal publishing high quality research articles in almost all branches of medicine. The quality of printing of figures and tables is excellent and comparable to any International journal. An added advantage is nominal publication charges and monthly issue of the journal and more chances of an article being accepted for publication. Moreover being a multi-specialty journal an article concerning a particular specialty has a wider reach of readers of other related specialties also. As an author and reviewer for several years I find this Journal most suitable and highly recommend this Journal."
Best regards,
C.S. Ramesh Babu,
Associate Professor of Anatomy,
Muzaffarnagar Medical College,
Muzaffarnagar.
On Aug 2018




Dr. Arundhathi. S
"Journal of Clinical and Diagnostic Research (JCDR) is a reputed peer reviewed journal and is constantly involved in publishing high quality research articles related to medicine. Its been a great pleasure to be associated with this esteemed journal as a reviewer and as an author for a couple of years. The editorial board consists of many dedicated and reputed experts as its members and they are doing an appreciable work in guiding budding researchers. JCDR is doing a commendable job in scientific research by promoting excellent quality research & review articles and case reports & series. The reviewers provide appropriate suggestions that improve the quality of articles. I strongly recommend my fraternity to encourage JCDR by contributing their valuable research work in this widely accepted, user friendly journal. I hope my collaboration with JCDR will continue for a long time".



Dr. Arundhathi. S
MBBS, MD (Pathology),
Sanjay Gandhi institute of trauma and orthopedics,
Bengaluru.
On Aug 2018




Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
The journal has a monthly publication and the articles are published quite fast. In time compared to other journals. The on-line first publication is also a great advantage and facility to review one's own articles before going to print. The response to any query and permission if required, is quite fast; this is quite commendable. I have a very good experience about seeking quick permission for quoting a photograph (Fig.) from a JCDR article for my chapter authored in an E book. I never thought it would be so easy. No hassles.
Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
My best wishes to Dr. Hemant Jain and all the editorial staff of JCDR for their untiring efforts to bring out this journal. I strongly recommend medical fraternity to publish their valuable research work in this esteemed journal, JCDR".



Dr. Mamta Gupta
Consultant
(Ex HOD Obs &Gynae, Hindu Rao Hospital and associated NDMC Medical College, Delhi)
Aug 2018




Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.


Authors are the souls of any journal, and deserve much respect. To publish a journal manuscripts are needed from authors. Authors have a great responsibility for producing facts of their work in terms of number and results truthfully and an individual honesty is expected from authors in this regards. Both ways its true "No authors-No manuscripts-No journals" and "No journals–No manuscripts–No authors". Reviewing a manuscript is also a very responsible and important task of any peer-reviewed journal and to be taken seriously. It needs knowledge on the subject, sincerity, honesty and determination. Although the process of reviewing a manuscript is a time consuming task butit is expected to give one's best remarks within the time frame of the journal.
Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
Timely publication of journal: Publication of manuscripts and bringing out the issue in time is one of the positive aspects of JCDR and is possible with strong support team in terms of peer reviewers, proof reading, language check, computer operators, etc. This is one of the great reasons for authors to submit their work with JCDR. Another best part of JCDR is "Online first Publications" facilities available for the authors. This facility not only provides the prompt publications of the manuscripts but at the same time also early availability of the manuscripts for the readers.
Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
It is well said that "happy beginning is half done" and it fits perfectly with JCDR. It has grown considerably and I feel it has already grown up from its infancy to adolescence, achieving the status of standard online e-journal form Indian continent since its inception in Feb 2007. This had been made possible due to the efforts and the hard work put in it. The way the JCDR is improving with every new volume, with good quality original manuscripts, makes it a quality journal for readers. I must thank and congratulate Dr Hemant Jain, Editor-in-Chief JCDR and his team for their sincere efforts, dedication, and determination for making JCDR a fast growing journal.
Every one of us: authors, reviewers, editors, and publisher are responsible for enhancing the stature of the journal. I wish for a great success for JCDR."



Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
E-mail: drrajendrak1@rediffmail.com
On May 11,2011




Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
Areas for improvement: In certain cases, I felt that the peer review process of the manuscripts was not up to international standards and that it should be strengthened. Also, the number of manuscripts in an issue is high and it may be difficult for readers to go through all of them. The journal can consider tightening of the peer review process and increasing the quality standards for the acceptance of the manuscripts. I faced occasional problems with the online manuscript submission (Pre-publishing) system, which have to be addressed.
Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."



Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
E-mail: ravi.dr.shankar@gmail.com
On April 2011
Anuradha

Dear team JCDR, I would like to thank you for the very professional and polite service provided by everyone at JCDR. While i have been in the field of writing and editing for sometime, this has been my first attempt in publishing a scientific paper.Thank you for hand-holding me through the process.


Dr. Anuradha
E-mail: anuradha2nittur@gmail.com
On Jan 2020

Important Notice

Original article / research
Year : 2022 | Month : May | Volume : 16 | Issue : 5 | Page : IC01 - IC05 Full Version

Diagnostic Accuracy of Rapid Antigen Test for COVID-19 Infection: A Retrospective Analysis


Published: May 1, 2022 | DOI: https://doi.org/10.7860/JCDR/2022/52529.16321
Dhwani N Chauhan, Shambhavi Verma, Kishor V Jadhav, M Kiran Kumar, Naresh T Chauhan, Abhay B Kavishvar, Jayesh K Kosambiya

1. Resident, Department of Community Medicine, Government Medical College, Surat, Gujarat, India. 2. Resident, Department of Community Medicine, Government Medical College, Surat, Gujarat, India. 3. Tutor, Department of Community Medicine, Government Medical College, Surat, Gujarat, India. 4. Resident, Department of Community Medicine, Government Medical College, Surat, Gujarat, India. 5. Assistant Professor, Department of Community Medicine, Government Medical College, Surat, Gujarat, India. 6. Associate Professor, Department of Community Medicine, Government Medical College, Surat, Gujarat, India. 7. Professor and Head, Department of Community Medicine, Government Medical College, Surat, Gujarat, India.

Correspondence Address :
Naresh T Chauhan,
B-1103, Shreepad Seasons, Palanpore, Surat, Gujarat, India.
E-mail: drnareshchauhan@rediffmail.com

Abstract

Introduction: For the diagnosis of Coronavirus Disease 2019 (COVID-19), Real-Time Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) is a laboratory-based technique and is considered a gold standard test, but is time consuming. A Rapid Antigen Test (RAT) is used for screening which is an immunoassay that identifies the presence of a viral antigen causing infection at the point of care. The RAT is quick, inexpensive, easily accessible and doesn’t need lab handling or sample preprocessing.

Aim: To measure the sensitivity, specificity, Negative Predictive Value (NPV) and Positive Predictive Value (PPV) of RAT in comparison to RT-PCR.

Materials and Methods: This retrospective study was conducted in Department of Community Medicine at Government Medical College (tertiary care centre), Surat, Gujarat, India, using secondary data from 1st July 2020 to 5th Dec 2020. The samples were collected from all the patients of Acute Respiratory Illness (ARI), Severe Acute Respiratory Illness (SARI), Influenza Like Illness (ILI), the suspected COVID-19 cases and all walk-in patients for testing or treatment purposes. A total of 264 participants enrolled in the study underwent both the RAT and RT-PCR tests. The sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were calculated using MS Excel Statistical Package for the Social Sciences (SPSS) version 17.0.

Results: Total 264 cases were analysed, amongst which 161 (60.9%) were males and 103 (39.1%) were females and the mean age of the patient was 41.6 years and 36.8 years for males and females, respectively. The overall sensitivity was 52.47%, specificity was 87.11%, PPV was 71.62% and the NPV was 74.73%. While among symptomatic patients, sensitivity was 55.55%, specificity was 88.54%, PPV was 76.97% and NPV was 74.35%.

Conclusion: Because of the low sensitivity of the RAT, if used alone, a high number of false negative cases will be resulted. Hence, it is employed in community and clinical settings as sequential screening in conjunction with RT-PCR, which results in improved net gain and aids in disease transmission control.

Keywords

Coronavirus disease 2019, Positive predictive value, Sensitivity, Specificity

The Coronavirus Disease 2019 (COVID-19) now known as Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV-2) is a global pandemic disease that emerged in 2019, is a major public health challenge and continued to cause devastation worldwide (1). Until now, as per the World Health Organisation (WHO), COVID-19 situation update, there were more than 100 million confirmed cases and more than 2 million deaths reported worldwide. In India, it has affected more than 11 million cases out of which more than 11 million cases were recovered and more than 1 lac died while more than 50 million have been vaccinated according to WHO coronavirus global data (2). The clinical features of this disease vary from strain to strain it ranges from asymptomatic cases to mild and severe respiratory illness. The symptoms may be fever, cough, cold, breathlessness and diarrhoea. People aged above 65 years and people of all ages with severe chronic medical conditions like hypertension, diabetes mellitus, lung diseases, heart diseases are at higher risk of succumbing to severe COVID-19 (3).

It is very important in clinical fields to confirm the clinical diagnosis with laboratory tests which is an integral part of diagnosis because medical decisions are 70% dependent on laboratory tests (4). One important aspect of limiting SARS-CoV-2 spread is through laboratory tests which detects the presence of causative virus to ensure the detection of the cases earlier and accurate diagnosis of the infection through breaking the chain of transmission by isolation and contact tracing, help in deciding the appropriate treatment decreasing patient’s expenditure and other harms of misdiagnosis (1),(5). But, it is rare to find a test that is perfect in terms of 100% sensitivity and specificity (4). Therefore, it has to be evaluated for its accuracy, technique, site and quality of sampling (4). Validity can be measured by sensitivity and specificity which can be done by comparing it with the gold standard test (4).

For diagnosing COVID-19, there were major challenges faced (6). Diagnostic strategies used in COVID-19 to identify current infection, rule out other infections, identify the appropriate people in need of hospitalisation, to test for past infections and immune response (6). The Real-Time Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) is considered as a gold standard diagnostic test (7),(8),(9), while Rapid Antigen Test (RAT) as a screening test (9). Such tests identify previous COVID-19 infections and may help to confirm the presence of current infection (6). The RT-PCR requires proper centralised laboratory infrastructure and laboratory facilities. It is time consuming as it takes around 5-6 hours. Moreover, transportation can cause a delay in the result and requires more precautions and preprocessing of the samples which becomes difficult and is not available every time. But, as the turn-around time for the diagnostic result is more, it limits the potential for diagnosis to lead to reductions in transmission (5),(9). Moreover, the demand for RT-PCR has outrun its precarious availability (7). So, it is not feasible to carry out RT-PCR tests under every circumstance. So, the need for rapid diagnostic tests arises that can be performed at a time.

A RAT is quick, inexpensive, easily accessible, easily transportable and doesn’t need lab handling or sample preprocessing. Therefore, it can decrease the pressure on overburdened centralised testing and the shortage of RT-PCR reagents that have occurred worldwide (4). It does not require laboratory infrastructure, precautions during transportation and preprocessing of samples, though tests active infection (4),(5),(10),(11). But, its lower sensitivity has limited adoption in clinical settings (5). At the same time, the requirements of RT-PCR have outrun its stock. Thus, RATs used for mass screening or community surveillance could control the pandemic by quickly isolating individuals during their incubation period to prevent disease transmission (10).

In few studies (4),(12), overall sensitivity of the RAT compared with laboratory-based testing was reported 94% (95% CI: 86-98) and an overall specificity of 100% (99-100) but its accuracy has not been studied in Gujarat. So, the present study may help to evaluate the rapid test and will give valuable insight into COVID-19 testing strategy.

The objective of the present study was to evaluate the sensitivity, specificity, Positive Predictive Value (PPV) and Negative Predictive Value (NPV) of the RAT which has remained a mainstay of identifying cases in the field, in comparison to RT-PCR.

Material and Methods

This retrospective study was conducted in Department of Community Medicine at Government Medical College (tertiary care centre), Surat, Gujarat, India, using secondary data from 1st July 2020 to 5th Dec 2020 and were analysed in August 2021. The study was conducted in accordance with the ethical standards and the approval has been obtained from the Institutional Human Research and Ethical Committee (No. GMCS/STU/ETHICS/Approval/8673/20).

Inclusion and Exclusion criteria: All the cases having details of both the tests i.e, RAT and RT-PCR tests were included in the study and cases with incomplete records were excluded from the study.

Total 264 cases admitted within the study period were enrolled in the study. The COVID-19 test data were obtained from the records from 1st July to 5th December 2020. This secondary data has the records of the samples collected from all the Acute Respiratory Illness (ARI) patients, Severe Acute Respiratory Illness (SARI), Influenza Like Illness (ILI), suspected COVID-19 cases or asymptomatic and presented for screening for testing or treatment purposes (Table/Fig 1).

Study Procedure

A nasopharyngeal swab was taken through sterile technique from each patient and was examined for RAT (SD Biosensor) immediately whereas another sample was collected in viral transport media and was sent for RT-PCR test to microbiology laboratory at tertiary care hospital keeping it in cold boxes maintaining 2-8°C temperature and taking all the proper precautions for transportation.

The following data were collected which included age, sex, address, date of OPD, the onset of symptoms, presence of symptoms like fever, cough, cold, breathlessness, diarrhoea, RAT results and RT-PCR results.

The results of RAT were compared with the gold standard RT-PCR tests to obtain sensitivity, specificity, PPV and NPV. The sensitivity of the RAT was calculated as the proportion of all those who resulted positive through the confirmatory RT-PCR method, while, the specificity of the RAT was calculated from the proportion of all those who resulted negative through the RT-PCR method.

Statistical Analysis

Analysis was done using Microsoft Excel and Statistical Package for the Social Sciences (SPSS) version 17.0. The information obtained from the results of the test was summarised in the form of a 2×2 contingency table.

Results

Total 264 cases were analysed for diagnostic accuracy. Amongst them 161 (60.9%) were male and 103 (39.1%) were female. The mean age of the patient was 41.6 years and 36.8 years for males and females respectively. The median duration for the onset of symptoms and visit to health facility was two days (IQR:1-3). The data in (Table/Fig 2) showing distribution according to the results of RAT and RT-PCR.

The RAT had higher overall specificity than sensitivity compared to RT-PCR (Table/Fig 3). The sensitivity, specificity and PPV of RAT increased in symptomatic cases than overall cases (Table/Fig 3).

Out of 190 Rapid Antigen COVID-19 negative results, symptomatic cases were higher which on further confirmation through RT-PCR test found 40 (21.05%) positive results (Table/Fig 4).

All those negative results of the RAT irrespective of their symptomatic status resulted in 48 (25.26%) positive through RT-PCR that could fail to diagnose, if, RAT is done alone (Table/Fig 4).

Out of the total 40 false negative by RAT but RT-PCR positive symptomatic patients, the majority were having cough 28 (70%) followed by fever 26 (65%) and both fever and cough 18 (45%) (Table/Fig 5).

Discussion

The SARS-CoV-2 is a major public health challenge globally. During this study, the incidence of the cases in the city of South Gujarat was at its peak. Considering, the RT-PCR test as the standard, the sensitivity of the RAT was found to be 52.47% (55.55% and 27.27% in symptomatic and asymptomatic individuals, respectively) and the specificity was high overall (87.11%). A study by Kanji JN et al., shows that 44.83% was the sensitivity (13). A study by Lanser L et al., showed Panbio™ antigen test 60.8% sensitivity which seems to be poor (9). A study in Canada shows that 42% resulted in positive results by polymerase chain reaction method (14). The similar results of PPV (70%) were seen by Panbio™ test compared to the results of PPV in the present study (71.62%) (13).

Another study of comparative evaluation of RATs for diagnosis of COVID-19 shows that RATs show ≥80% sensitivity and ≥97% specificity (14). A study by Adamson B et al., shows that RATs lag to detect COVID-19 and it must not be suitable for routine screening of asymptomatic cases to prevent the spread of the virus (15). Given its sensitivity of around 80%, antigen tests like PanbioTM COVID-19 antigen test, might be suitable for quickly identifying infectious subjects in primary care with symptoms consistent with COVID-19 infections (9).

SARS-CoV-2 infected people with moderate to high virus loads were quickly identified with the Panbio™ COVID-19 RAT. Antigen tests have 1.0% specificity in all types of patients and can be a useful method with a high PPV for COVID pandemic control. It might be utilised as an alternative for PCR in these individuals to avoid the delays and high labour costs caused by the widespread usage of PCRs. The test has a sensitivity of 86.5% in the group of symptomatic patients with fewer than seven days of evolution, which is lower than the sensitivity reported in the technical data sheet of the test (16). A study by Lefever S et al., shows no false positive results. An 100% sensitivity was obtained with a high viral load in both symptomatic and asymptomatic patients. The proportion of asymptomatic participants with a low viral load was substantially higher than that of symptomatic participants, explaining why asymptomatic people had lower overall sensitivity than symptomatic ones. When compared to RT-PCR, Ag-RDT has a lower sensitivity and a higher specificity (17).

According to a recent Cochrane meta-analysis, the average sensitivity was 75.1% (CI, 57.3-87.1%) and 88.1% (CI, 84.2%-91.1%) in Abbott-Panbio and SD Biosensor rapid testing kits respectively while specificity were 99.5% (CI, 98.7%- 99.8%) in Abbott-Panbio and 99.1% (CI, 97.8%-99.6%) in SD Biosensor rapid testing kits amongst symptomatic patients (12). The Liaison antigen test had a sensitivity of 67.7% and a specificity of 100% reported, which is comparable to the present study. The sensitivity of the Liaison antigen test was 65.7% (CI, 58.9% to 71.9%) and the specificity was 100% (CI, 97.8% to 100%) in a study by Lefever S et al., (17). A study by Fernandez-Montero A et al., shows Roche SARS-CoV-2 RAT has been proven to be highly sensitive and specific on symptomatic patients, meeting WHO recommended criteria of 80% sensitivity and 97% specificity. Compared with the RT-PCR test, the Roche-rapid test had a sensitivity of 71.43% and a specificity of 99.68% with moderate concordance (18). Comparison of present study with contrast studies is shown in (Table/Fig 6) (9),(10),(11),(12),(13),(14),(15),(16),(17),(18).

For effective implementation of the test, track and isolation, an accurate diagnostic test is of paramount importance to control the pandemic. SARS-CoV-2 is a serious infectious disease in which efficient measures and timely management is required and its false negative results might lead to free contact of the patient which could lead to transmission of the disease. To overcome this, conduction of the screening RAT along with the confirmatory RT-PCR test simultaneously is necessary (11),(19),(20).

Rapid diagnostic tests have a crucial role in the foundation of national testing strategy. Because of its low sensitivity, vigilant interpretation of its results is essential for evaluation. It’s use has been limited and not completely adopted in the clinical setting but, it’s increase in the net gain has resulted in controlling disease transmission by providing decentralised and mobile testing rapidly diagnosing results in public places or at community which is well suited to low-resource environments (1).

A study by Mak GC et al., shows that Biocredit COVID-19 Ag was 105 times less sensitive than RT-PCR in terms of LOD (Biocredit COVID-19 Ag: 10-2; RT-PCR: 10-7) in the reference RAD kit. SARS-CoV-2 infection can be detected with the help of RAD kits. The findings were in line with the WHO recommendation to test symptomatic cases within the first 5-7 days of illness. It’s important to strike a balance between speed and sensitivity. A COVID-19 filter can be failed, even if, the diagnostic test has a high analytical sensitivity (11).

All those 190 RAT negative results have been confirmed through RT-PCR which led to the detection of 25% (n=48; including symptomatic n=40 and asymptomatic n=8) more cases that could be missed out if RAT is done exclusively. The compatible symptoms of the disease turned out to be more positive on the RT-PCR test. Therefore, the strategy of using a more sensitive test i.e., RT-PCR is strengthened, if there is high clinical suspicion for COVID-19 in cases of having cough (30.11%), fever (27.96%) and both fever and cough (19.35%) which were failed to get diagnosed. Optimum interpretation of the RAT results should take into account the patient’s clinical features, history of exposure, the prevalence of COVID-19 in the community and the test’s performance characteristics.

Limitation(s)

The outcome of the study was subjected to limitations concerning any COVID-19 compatible symptoms that might not be collected beyond the chief complaint during the time of pandemic and the symptoms might be underestimated. Exposure history was also not assessed. RT-PCR detects the presence of viral Ribonucleic Acid (RNA) detecting past infection too and might not transmit the disease.

Conclusion

Indian Council of Medical Research (ICMR) recommended use of RAT use, as point of care screening of COVID-19, so, that we can do isolation, proper treatment and thereby, break the chain of transmission of SARS-CoV-2 disease. As it may happen that the rapid test fails to detect diseases in many cases, thus, it emphasises that it should not heavily relied on rapid test and it should be supplemented by RT-PCR in case of negative results. Finding of the present study document, the sensitivity and specificity of RAT, it also concludes the proportion of symptomatic negative cases found positive on RT-PCR and the proportion of asymptomatic negative cases found positive on RT-PCR. So, the rational use of RAT in combination with RT-PCR is recommended, as per the guidelines.

Acknowledgement

The authors would like to acknowledge and thank all the resident doctors, intern doctors, and medical social workers, data operators of the Municipal Corporation and the staff of the Community Medicine and Microbiology of the tertiary care hospital of south Gujarat who made great contributions to bring this work to success.

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DOI and Others

DOI: 10.7860/JCDR/2022/52529.16321

Date of Submission: Dec 12, 2021
Date of Peer Review: Jan 06, 2022
Date of Acceptance: Feb 19, 2022
Date of Publishing: May 01, 2022

AUTHOR DECLARATION:
• Financial or Other Competing Interests: None
• Was Ethics Committee Approval obtained for this study? Yes
• Was informed consent obtained from the subjects involved in the study? No
• For any images presented appropriate consent has been obtained from the subjects. NA

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