Recent studies have suggested that chest computed tomography (CT) scans could be used as a primary screening or diagnostic tool for coronavirus disease 2019 (COVID-19) in epidemic areas. To study that, some scientifics have created a project to perform a meta-analysis to evaluate diagnostic performance measures, including predictive values, of chest CT and initial reverse transcriptase-polymerase chain reaction (RT-PCR). 

For the meta-analysis, MEDLINE and Embase articles were searched from January 1, 2020 to April 3, 2020 for studies on COVID-19 that reported the sensitivity and/or specificity of CT scans and/or RT-PCR assays. The pooled sensitivity and specificity were estimated by using random-effects models. The actual prevalence (i.e., the proportion of confirmed patients among those tested) in eight countries was obtained from web sources, and the predictive values were calculated. Meta-regression was performed to reveal the effect of potential explanatory factors on the diagnostic performance measures.

They found out that the pooled sensitivity was 94% (95% CI: 91%, 96%) for chest computed tomography (CT) and 89% (95% CI: 81%, 94%) for reverse transcriptase-polymerase chain reaction (RT-PCR). The pooled specificity of chest CT was 37% (95% CI: 26%, 50%). Given the low specificity of chest CT, a large gap in the positive predictive value (PPV) between chest CT and RT-PCR in low-prevalence regions was noted. Specifically, in countries with a prevalence less than 10%, the PPV of RT-PCR was more than ten times higher than that of CT scans. Nevertheless, the negative predictive value of both methods ranged from 99.0% to 99.9%. The results imply that the usage of chest CT scans in low-prevalence regions could induce a large number of false-positive results. False positive results may lead to further diagnostic testing, greater medical costs and workload of medical staff as well as patient anxiety.  

In conclusion, chest CT scans for the primary screening or diagnosis of coronavirus disease 2019 would not be beneficial in a low-prevalence region due to the substantial rate of false-positives. A cost-effectiveness analysis and assessment of practicability are warranted for chest CT in high-prevalence regions.