Chest X-Ray Has Poor Sensitivity and Prognostic Significance in COVID-19: A Propensity Matched Database Study

Abstract

<jats:p>Objectives: To identify the diagnostic accuracy of common imaging modalities, chest X-ray (CXR) and computed tomography (CT) for diagnosis of COVID-19 in the general emergency population in the UK and to find the association between imaging features and outcomes in these patients. Design: Retrospective analysis of electronic patient records Setting: Tertiary academic health science centre and designated centre for high consequence infectious diseases in London, UK. Participants: 1,198 patients who attended the emergency department with paired RT-PCR swabs for SARS-CoV 2 and CXR between 16th March and 16th April 2020 Main outcome measures: Sensitivity and specificity of CXR and CT for diagnosis of COVID-19 using the British Society of Thoracic Imaging reporting templates. Reference standard was any reverse transcriptase polymerase chain reaction (RT-PCR) positive naso-oropharyngeal swab within 30 days of attendance. Odds ratios of CXR in association with vital signs, laboratory values and 30-day outcomes were calculated. Results: Sensitivity and specificity of CXR for COVID-19 diagnosis were 0.56 (95% CI 0.51-0.60) and 0.60 (95% CI 0.54-0.65), respectively. For CT scans these were 0.85 (95% CI 0.79-0.90) and 0.50 (95% CI 0.41-0.60), respectively. This gave a statistically significant mean increase in sensitivity with CT compared with CXR, of 29% (95% CI 19%-38%, p&lt;0.0001). Specificity was not significantly different between the two modalities. Chest X-ray findings were not statistically significantly or clinical meaningfully associated with vital signs, laboratory parameters or 30-day outcomes. Conclusions: Computed tomography has substantially improved diagnostic performance over CXR in COVID-19. CT should be strongly considered in the initial assessment for suspected COVID-19. This gives potential for increased sensitivity and considerably faster turnaround time, where capacity allows and balanced against excess radiation exposure risk.</jats:p>

The COVID‐19 Worsening Score (COWS)—a predictive bedside tool for critical illness

“…In a retrospective single‐center study evaluating 1,198 ED COVID‐19 patients, the accuracy of both CXR and computerized CT scan for diagnosis of COVID‐19 was investigated. Sensitivity and specificity of CXR were 0.56 and 0.60, whereas for CT scan these were 0.85 and 0.50, respectively 7 . Despite its low specificity, CT confirmed the diagnosis of COVID‐19 in patients with a false‐negative RT‐PCR as demonstrated in Chen et al study.…”

Modelling of hypothetical SARS-CoV-2 point-of-care tests on admission to hospital from A&E: rapid cost-effectiveness analysis

“…As described in Waiting for a decision on bed allocation, the model allows a negative SARS-CoV-2 test result not to be acted on if the clinician has a strong belief, based on clinical symptoms and chest imaging, that the result may be a false negative. The proportion of patients with clinical symptoms and COVID-19 who were assumed to have chest imaging results suggestive of COVID-19 was 56% (taken from Borakati et al 18 ). The proportion of patients with clinical symptoms but without COVID-19 who were assumed to have chest imaging results suggestive of COVID-19 was 40% (taken from Borakati et al 18 ), equating to a specificity of detecting COVID-19 of 60%.…”

“…The proportion of patients with clinical symptoms and COVID-19 who were assumed to have chest imaging results suggestive of COVID-19 was 56% (taken from Borakati et al 18 ). The proportion of patients with clinical symptoms but without COVID-19 who were assumed to have chest imaging results suggestive of COVID-19 was 40% (taken from Borakati et al 18 ), equating to a specificity of detecting COVID-19 of 60%. These values were for chest X-ray.…”

“…These values were for chest X-ray. In sensitivity analyses, the values reported by Borakati et al 18 for computed tomography were used, which were a sensitivity of detecting COVID-19 of 85% and a specificity of 50%. In this study, polymerase chain reaction results were assumed to be the gold standard.…”

“…For patients admitted to hospital without SARS-CoV-2 infection the average number of nights spent in hospital was 7.5. 8 For simplicity, it was assumed that this could be represented by a triangular distribution (1,5,12) for patients aged ≤ 69 years and a triangular distribution (6,12,18) for patients aged ≥ 70 years. For simplicity, it was assumed that these outcomes were independent of other outcomes (discharge, ICU care or death).…”