COVID-19 Evidence Alerts
from McMaster PLUSTM

Current best evidence for clinical care (more info)

Diagnosis Kim H, Hong H, Yoon SH Diagnostic Performance of CT and Reverse Transcriptase Polymerase Chain Reaction for Coronavirus Disease 2019: A Meta-Analysis. Radiology. 2020 Sep;296(3):E145-E155. doi: 10.1148/radiol.2020201343. Epub 2020 Apr 17.

Background Recent studies have suggested that chest CT scans could be used as a primary screening or diagnostic tool for coronavirus disease 2019 (COVID-19) in epidemic areas. Purpose 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). Materials and Methods Medline and Embase were searched from January 1, 2020, to April 3, 2020, for studies on COVID-19 that reported the sensitivity, specificity, or both of CT scans, RT-PCR assays, or both. The pooled sensitivity and specificity were estimated by using random-effects models. The actual prevalence (ie, 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. Results The pooled sensitivity was 94% (95% confidence interval [CI]: 91%, 96%; I2 = 95%) for chest CT and 89% (95% CI: 81%, 94%; I2 = 90%) for RT-PCR. The pooled specificity was 37% (95% CI: 26%, 50%; I2 = 83%) for chest CT. The prevalence of COVID-19 outside China ranged from 1.0% to 22.9%. For chest CT scans, the positive predictive value (PPV) ranged from 1.5% to 30.7%, and the negative predictive value (NPV) ranged from 95.4% to 99.8%. For RT-PCR, the PPV ranged from 47.3% to 96.4%, whereas the NPV ranged from 96.8% to 99.9%. The sensitivity of CT was affected by the distribution of disease severity, the proportion of patients with comorbidities, and the proportion of asymptomatic patients (all P < .05). The sensitivity of RT-PCR was negatively associated with the proportion of elderly patients (P = .01). Conclusion Outside of China where there is a low prevalence of coronavirus disease 2019 (range, 1%-22.9%), chest CT screening of patients with suspected disease had low positive predictive value (range, 1.5%-30.7%). © RSNA, 2020 Online supplemental material is available for this article.

Discipline / Specialty Area Score
Public Health
Pediatrics (General)
Family Medicine (FM)/General Practice (GP)
General Internal Medicine-Primary Care(US)
Infectious Disease
Intensivist/Critical Care
Emergency Medicine
Pediatric Emergency Medicine
Pediatric Hospital Medicine
Comments from MORE raters

Emergency Medicine rater

As the authors conclude, CT thorax is likely less sensitive in a low prevalence and/or low severity of illness populations; however, the point made in the text regarding "unclear risk of bias" for half of the included studies with respect to blinding of the radiologists to the Covid-PCR results should be emphasized.

Infectious Disease rater

The article presents a timely analyses of commonly used and available resources for COVID-19 diagnosis that has been marred by lack of confidence given low sensitivity and specificity reported from various studies/locations. The lack of standardized tests given the urgency due to the pandemic has only caused uncertainty and this article helps dispel some of it.

Intensivist/Critical Care rater

Most guidelines recommend against screening with CT scans, and this meta-analysis seems to confirm that there is low usefulness for using CT scans for testing for COVID-19.

Pediatric Emergency Medicine rater

As a Paediatrician, I find these results, if extrapolated to our adolescent population, might save a lot of them from unwarranted radiation. It would be nice to know if the researchers did a sub-analysis for children based on age sets until adolescence.