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CT screening for COVID-19 in asymptomatic patients before hospital admission
Sho Uchida1, Shunsuke Uno1, Yoshifumi Uwamino2
1Department of Infectious Diseases, Keio University School of Medicine, 35, Shinanomachi, Shinjuku-ku, Tokyo, 160-8582, Japan.
Insights
Chest CT scans showed 0% sensitivity for detecting COVID-19 in low prevalence settings. CT screening is not recommended for asymptomatic patients in areas with low coronavirus disease (COVID-19) prevalence.
Area of Science:
- Medical Imaging
- Infectious Disease Diagnostics
- Epidemiology
Background:
- Effective COVID-19 diagnosis is crucial during the pandemic.
- CT screening has shown utility in high prevalence areas.
- Limited data exists on CT screening efficacy in low prevalence regions.
Purpose of the Study:
- To evaluate the diagnostic performance of CT screening for COVID-19 in a low prevalence area.
- To assess the utility of pre-admission CT screening in asymptomatic surgical patients.
Main Methods:
- Retrospective analysis of 292 asymptomatic patients undergoing pre-admission screening at Keio University Hospital.
- Simultaneous PCR testing with nasopharyngeal swabs and chest CT scans were performed.
- Screening occurred from April 6, 2020, to May 29, 2020, in Tokyo.
Main Results:
- Three patients tested PCR-positive for COVID-19, all with negative CT findings (sensitivity 0%, PPV 0%).
- Nine patients had positive CT findings, with specificity of 96.9% and NPV of 98.9%.
- CT screening demonstrated very low sensitivity in this low prevalence cohort.
Conclusions:
- CT screening is not effective for diagnosing COVID-19 in low prevalence areas like Tokyo.
- The utility of CT screening is highly dependent on disease prevalence.
- Establishment of prevalence-based criteria for CT screening is recommended.
Introduction:
In the novel coronavirus disease (COVID-19) pandemic era, it is essential to rule out COVID-19 effectively to prevent transmission in both communities and medical facilities. According to previous reports in high prevalence areas, CT screening may be useful in the diagnosis of COVID-19. However, the value of CT screening in low prevalence areas has scarcely been reported.
Methods:
This report examines the diagnostic efficacy of CT screening before admission to a hospital in Tokyo. We conducted a retrospective analysis at Keio University Hospital from April 6, 2020, through May 29, 2020. We set up an outpatient screening clinic on April 6 for COVID-19, administering both PCR with nasopharyngeal swabs and chest CT for all patients scheduled for surgery under general anesthesia.
Results:
A total of 292 asymptomatic patients were included in this study. There were three PCR-positive patients, and they all had negative CT findings, which revealed that both the sensitivity and positive predictive value of CT (PPV) were 0%. There were nine CT-positive patients; the specificity and the negative predictive value (NPV) were 96.9% and 98.9%, respectively.
Conclusion:
CT screening was not useful in low prevalence areas at this time in Tokyo, even with the inclusion of the most prevalent phase. Given that the utility of CT screening depends on disease prevalence, the criteria for performing CT screening based on the prevalence of COVID-19 should be established.
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