Diagnostic accuracy of chest x-ray as a frontline diagnostic tool for detecting covid-19 pneumonia -our study in a tertiary level covid hospital

Introduction: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a new virus recently isolated from humans. SARS-CoV-2 was discovered to be the pathogen responsible for a cluster of pneumonia cases associated with severe respiratory disease that occurred in December 2019 in Wuhan, China. Chest Radiography has very limited role in diagnosis of early and mild course of disease but it showed significant role in intermediate to advanced course of disease as well as during follow-up.
Purpose: The purpose of our study is to correlate chest x-ray findings with RT-PCR, describe various chest x-ray findings and monitor patient’s disease progression over time.
Materials and Methods: We selected 152 patients from tertiary level COVID hospital from 3rd April to 9th June who had symptoms of COVID-19 (fever, cough, sore throat, dyspnoea). All patients performed RT-PCR nasopharyngeal and throat swab, CXR on admission and during follow-up. RT-PCR results were considered the reference standard. A CXR severity scoring index was determined for each lung. A total severity score was calculated by summing both lung scores.
Results: The study was composed of 152 clinically suspected patients, of which 140 patients were tested positive for COVID-19 RT-PCR. 82 of 140 RT-PCR positive patients at initial scan and 16 patients in follow-up scan showed chest X-ray abnormalities. 12 patients were tested negative for RT-PCR, out of which 4 patients showed chest X-ray abnormalities (false positive). Most common findings of chest X-ray were consolidation (69,67.6%) followed by ground glass opacity (36,35.3%), reticulation and interstitial thickening (34, 33.3%). Pleural effusion was found in 4 patients (3.9%). Chest x-ray of one patient (1,0.9%) revealed cardiomegaly, with smooth cardiac boarders suggestive of pericardial effusion. Most cases showed peripheral predominance (65,63.7%) with Bilateral lung involvement (66, 64.7%) and lower zonal (77, 75.5%) distribution. Total severity scores ranged from 0 to 8 and calculated at baseline, first week and second week of follow-up scan. Peak severity was reached at 12-14 days of disease onset. By using RT-PCR results as standard, overall sensitivity and specificity of chest radiography were 70% and 66.7% respectively in the diagnosis of COVID-19.
Conclusions: Chest radiography can be used as initial diagnostic tool for triaging of COVID-19 in symptomatic patients and useful for monitoring chest manifestations and extent of lung involvement and disease progression over time.