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Review Article | DOI: https://doi.org/10.31579/2690-8794/122
1 Professor of Pathology, Consultant Microbiologist, Al Nafees Medical College & Hospital, Islamabad, Pakistan
2 Professor of Pathology, Consultant Microbiologist, National University of Medical Sciences, Rawalpindi. Pakistan
3 Assistant Professor of Pathology, Consultant Microbiologist, National University of Medical Sciences, Rawalpindi. Pakistan.
*Corresponding Author: Humaira Zafar, Prof of Pathology, Consultant Microbiologist, Department of Pathology, Al Nafees Medical College & Hospital, Isra University Islamabad Campus, Pakistan.
Citation: Humaira Zafar, Irfan Ali Mirza and Wajid Hussain (2022) Fundamentals of using a Combined Diagnostic Approach for Covid 19 By RT-PCR and HR-CT Scan for early Case Recognition J, Clinical Medical Reviews and Reports. 4(3); DOI: 10.31579/2690-8794/122
Copyright: © 2022, Humaira Zafar, This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Received: 24 January 2022 | Accepted: 12 February 2022 | Published: 21 March 2022
Keywords: COVID-19, RT PCR, HR-CT scan chest, combined diagnostic approach, early case recognition
The emergence of more and more variants of COVID 19 and not ending pandemic is still a top most concerns around the Globe. The diagnosis of COVID19 is still a bit challenging. The asymptomatic phase during incubation period of disease or prodromal symptoms, mislead the clinician to early diagnose a case. Therefore this short communication was aimed to highlight a combined diagnostic approach for COVID by using HRCT scan chest and RT – PCR. This will be helpful for the clinician to early diagnose and timely manage a case, ultimately a step forward to contain this disease and its mortality. This commentary concluded that the sensitivity along with specificity of HR-CT scan and PCR varies. This variation could be due to many factors like mode of analysis, machines used for HR-CT scan or RT-PCR, technical handling. Therefore, though it become costly but a combined diagnostic approach should be used to early diagnose and manage COVID.
The twilight of year 2019 brought the advent of severe acute respiratory syndrome Corona viral infection (SARS-CoV- II) epidemic in Wuhan China. It was subsequently named as Corona viral infection disease for the year 2019 (COVID-19). Afterwards it embraced more than two dozen countries across Globe, showing a mortality in millions of cases. It was labelled as a pandemic near the first light of year 2020. Tracing the history, few years back, epidemic was observed from member of same group i.e Middle East respiratory syndrome Corona viral infection (MERS-CoV) in Saudi Arabia. It took about thousands of subsists. From that time till date, despite the utmost efforts scientists are not much successful to spawn anti-viral [1]. Though the availability of various types of vaccines is considered to be proving effective for reducing the intensity of infection.
The commonly encountered symptoms ranges from mild to severe intensity. They can be fever, cough, myalgia, arthralgias, dyspnea, and pneumonia to life threatening progressive respiratory failure, ultimately leading to high mortality rate in at risk population. In view of pandemic insurgence, accurate diagnostic approach is the only way to contain this deadly illness. The precise approach encompasses both on clinical case evaluation and detection of SARS CoV II, RNA in respiratory secretions using reverse transcriptase polymerase chain reaction (RT-PCR) [2].
RT – PCR is considered as a gold for the diagnosis of COVID-19. However variability was observed regarding its sensitivity. The reason for this variability could be due to the detection of one, two or three genes (maximum), depending upon various government or private lab settings. Other highlighted reasons includes decreased viral load in early course of infection, absence of virus in nasopharyngeal sample, improper sample collection and transportation [3]. A study report by Fang Y et al (2020) concluded that the comparative sensitivity of high resolution computed tomography scan (HR-CT) is greater than RT PCR i.e 98% vs 71% respectively. Even the symptomatic cases with negative RT PCR were found to be positive for HRCT findings like the ground glass appearance, peripheral linear opacities, consolidation, and reticulation [4].
One Meta-analysis along with a systematic review published in the year 2021, described the comparative analysis of HR-CT scan with RT-PCR for early case recognition. Ten studies were included comprising of 6528 (n) patients. The estimated sensitivity of HR-CT ranged from 72% to 98%. While appraised specificity ranged from 22% to 96% respectively. The overall mean for HR-CT scan sensitivity was 91% along with the specificity 87% at 95% CI. Comparatively the sensitivity of RT-PCR was bit lower i.e 87%, along with a specificity of 99% at 95% CI. No clear conclusion was drawn. It was also described that the variation could be due to many reason i.e mode of analysis, machines used for HR-CT scan or RT-PCR, technical handling etc. 5 Besides both these tests, talking for the newly available modalities like antigen testing, brings on a huge debate. They have very less sensitivity and specificity and increase chances of cross reactivity with many diseases like typhoid and dengue. Though in common use due to easy availability and cost effectiveness, but can totally mislead, ultimately missing the accurate COVID diagnosis. Similarly antibody level estimation only helps identifying the immunity against COVID.
Therefore, whatsoever choice of diagnostic modalities and their result variation clinical correlation must always be done. From patients perspective negative results in an infected person divulges many reasons like poor sample quality, small amount of sample, inappropriate sampling time i.e too late or too early during the course of infection or inadequate storage of sample. It could be even technical reasons like viral mutation, or inhibition of the PCR reaction. Contrary positive results do not exclude bacterial infection or contamination with other viruses [6].
The devastating condition due to COVID 19 pandemic is not yet over. A vigilant approach will be required in upcoming months of winters to combat this lethal infection. Only by early case recognition and confirmation by a combined approach of RT-PCR along with HR-CT scan is a need of time to win the battle against this pandemic. The huge discussions regarding the pros and cons of both are there with evidence. But in current scenario we have to identify the best out of best. Therefore, the policy makers for health care system must look into this approach, which will be an added thing besides social distancing to contain infection. Hence, accurate and prompt diagnosis can be a step forward to reduce the morbidity and mortality rates.
The sensitivity along with specificity of HR-CT scan and PCR varies. This variation could be due to many factors like mode of analysis, machines used for HR-CT scan or RT-PCR, technical handling. Therefore, though it become costly but a combined diagnostic approach should be used to early diagnose and manage COVID.