Current best evidence for clinical care (more info)
Purpose: To determine the utility of chest radiography in aiding clinical diagnosis of coronavirus disease 2019 (COVID-19) utilizing reverse-transcription polymerase chain reaction (RT-PCR) as the standard of comparison.
Materials and Methods: A retrospective study was performed of persons under investigation for COVID-19 presenting to this institution during the exponential growth phase of the COVID-19 outbreak in New Orleans (March 13-25, 2020). Three hundred seventy-six in-hospital chest radiographic examinations for 366 individual patients were reviewed along with concurrent RT-PCR tests. Two experienced radiologists categorized each chest radiograph as characteristic, nonspecific, or negative in appearance for COVID-19, utilizing well-documented COVID-19 imaging patterns. Chest radiograph categorization was compared against RT-PCR results to determine the utility of chest radiography in diagnosing COVID-19.
Results: Of the 366 patients, the study consisted of 178 male (49%) and 188 female (51%) patients with a mean age of 52.7 years (range, 17 to 98 years). Of the 376 chest radiographic examinations, 37 (10%) exhibited the characteristic COVID-19 appearance; 215 (57%) exhibited the nonspecific appearance; and 124 (33%) were considered negative for a pulmonary abnormality. Of the 376 RT-PCR tests evaluated, 200 (53%) were positive and 176 (47%) were negative. RT-PCR tests took an average of 2.5 days ± 0.7 to provide results. Sensitivity and specificity for correctly identifying COVID-19 with a characteristic chest radiographic pattern was 15.5% (31/200) and 96.6% (170/176), with a positive predictive value and negative predictive value of 83.8% (31/37) and 50.1% (170/339), respectively.
Conclusion: The presence of patchy and/or confluent, bandlike ground-glass opacity or consolidation in a peripheral and mid to lower lung zone distribution on a chest radiograph obtained in the setting of pandemic COVID-19 was highly suggestive of severe acute respiratory syndrome coronavirus 2 infection and should be used in conjunction with clinical judgment to make a diagnosis.© RSNA, 2020.
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In this study, CXR was very specific but with low sensitivity (good PPV, poor NPV in the setting of high COVID19 prevalence). However there are several things to note that may not make this generalizable: 1) in this case, expert radiologists were used to interpret the films (could EM physicians or other specialists have the same performance); 2) the criteria used were very narrow that constituted as "positive", thus most films may not meet 'positive' criteria; 3) the findings used for 'positive' are similar for other disease processes; 4) with low prevalence of COVID-19, the performance characteristic (ie PPV) may be unacceptably low; 5) this is only helpful in the setting on a COVID-19 pandemic. It's not clear if another viral pandemic occurs that wasn't COVID-19, how this could be helpful.
The sensitivity was poor. However, with a high pretest probability, the CXR is useful.
As an Internist working at a COVID-19 clinic, I found these information very useful for my every day clinical practice.