The Diagnostic Value of CT scans in the Process of Diagnosing COVID-19 in  medical Centers

Afshin   Ostovar; Elham  Ehsani-Chimeh; Zeinab   Fakoorfard

doi:10.18502/htaa.v4i1.5866

Afshin Ostovar Osteoporosis Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran
Elham Ehsani-Chimeh National Institute for Health Research, Tehran University of Medical Sciences, Tehran, Iran
Zeinab Fakoorfard National Institute for Health Research, Tehran University of Medical Sciences, Tehran, Iran

DOI: https://doi.org/10.18502/htaa.v4i1.5866

Keywords: COVID-19; CT Scan; Health Technology Assessment (HTA); RT-PCR Test; Sensitivity; Specificity

Abstract

Background: Coronavirus disease (COVID-19) has spread around the world since the beginning of 2020. The definitive diagnosis of COVID-19 is the RT-PCR laboratory test. However, because of low sensitivity, the chest CT scan has become important for the rapid diagnosis and clinical decision-making.

Objectives: This study aims to define CT scan’ diagnostic value in diagnosing COVID-19 in medical centers.

Methods: This study is a rapid health technology assessment (HTA) and had two major phases. In phase 1, a rapid review was done for defining the sensitivity and specificity rate of CT. During this phase, studies related to the diagnostic and technical data on the use of CT in the diagnosis of COVID-19 were reviewed, and the sensitivity and specificity of CT in these studies were extracted. In phase 2, sequential testing was run to evaluate the diagnostic value of chest CT to diagnose COVID-19 according to two scenarios before and after adding RT-PCR
test results.

Results: CT scan has a high sensitivity for diagnosing cases of COVID-19. Due to its low specificity, relying on CT scans to diagnose COVID-19 alone in medical centers can lead to a significant proportion of false-positive cases. This study showed that if the probability of COVID-19 before the CT scan were about 50%, with a positive CT scan, this probability would be between 60 and 70% depending on the CT specificity.

Conclusions: With the available evidence, the use of a CT scan alone is not sufficient for diagnosis. The RT-PCR test is also necessary to improve the diagnosis and continue the treatment and isolation of patients.