Lung Ultrasound vs. Chest X-Ray Study for the Radiographic Diagnosis of COVID-19 Pneumonia in a High-Prevalence Population

BACKGROUND: The viral illness severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), more commonly known as Coronavirus 2019 (COVID-19), has become a global pandemic, infecting over 100 million individuals worldwide. OBJECTIVES: The objective of this study was to compare the test characteristics of point-of-care lung ultrasound (LUS) with chest x-ray study (CXR) at radiographically detecting COVID-19 pneumonia. METHODS: This was a single-center, prospective, observational study at an urban university hospital with > 105,000 patient visits annually. Patients ≥ 18 years old, who presented to the Emergency Department with predefined signs and symptoms of COVID-19, were eligible for enrollment. Each patient received an LUS using a portable, handheld ultrasound followed by a single-view, portable anteroposterior CXR. Patients with an abnormal LUS or CXR underwent a non-contrast-enhanced computed tomography scan (NCCT). The primary outcome was the radiographic diagnosis of COVID-19 pneumonia on NCCT. RESULTS: One hundred ten patients underwent LUS, CXR, and NCCT; 99 LUS and 73 CXRs were interpreted as positive; 81 NCCTs were interpreted as positive, providing a prevalence of COVID-19 pneumonia of 75% (95% confidence interval [CI] 66–83.2) in our study population. LUS sensitivity was 97.6% (95% CI 91.6–99.7) vs. 69.9% (95% CI 58.8–79.5) for CXR. LUS specificity was 33.3% (95% CI 16.5–54) vs. 44.4% (95% CI 25.5–64.7) for CXR. LUS positive predictive value and negative predictive value were 81.8% (95% CI 72.8–88.9) and 81.8% (95% CI 48.2–97.7), respectively, vs. 79.5% (95% CI 68.4–88), and 32.4% (95% CI 18–49.8), respectively, for CXR. CONCLUSION: LUS was more sensitive than CXR at radiographically identifying COVID-19 pneumonia.