Predictive Role of Chest Radiograph in COVID-19 Hospitalised Patients-A Retrospective Analysis

ABSTRACT

Introduction: The portable Chest Radiograph (CXR) has an indispensable role in large scale screening and diagnosis of Coronavirus Disease 2019 (COVID-19), especially in developing countries with limited resources. It can help in predicting the severity of lung involvement in the patients infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, especially in areas where the Computed Tomography (CT) is unavailable. Aim: To determine the prognostic value of CXR at clinical presentation in assessing the disease severity and its correlation with inflammatory markers in COVID-19 hospitalised patients. Materials and Methods: This was a single-centre retrospective study, conducted at Sri Ramachandra Institute of Higher Education and Research, from October 2020 to December 2020, on hospitalised COVID-19 patients. Clinically, the patients were categorised as mild, moderate and severe, based on their peripheral oxygen saturation- more than 94%, between 90-93%, and less than or equal to 89%, respectively. Blood samples, drawn at presentation to the hospital tested for various inflammatory markers proven to be predictive of disease severity, were documented for the analysis purpose. The CXRs, done at the presentation, were scored based on the number of zones involved and type of abnormality present (ground glassing, consolidation and septal thickening). The CXRs were scored a minimum '0' to a maximum of '9'. Correlation between the radiograph score and inflammatory markers was further analysed. Results: Among the 456 study patients, 71% had mild, 15% had moderate and 14% had severe COVID-19 infection. The mean CXR score in each category was 1, 3 and 4, respectively (p-value <0.001). The study groups were grouped as mild and non mild (included the moderate and severe categories). A criterion CXR score of 2 was able to differentiate mild and non mild cases (sensitivity was 78.29%, specificity was 77.98%, positive predictive values was 58.38%, negative predictive values was 90.11%), with an accuracy of 78.1%. The inflammatory markers like Neutrophil Lymphocyte Ratio (NLR), Absolute Lymphocyte Counts (ALC), eosinophil%, D-dimer, Lactate Dehydrogenas (LDH), Erythrocyte Sedimentation Rate (ESR), C-Reactive Protein (CRP), and ferritin showed statistically significant difference between the two groups (p-value<0.001). Conclusion: The CXR can be used as a screening and predictive tool for disease severity in developing countries where access to Computed Tomography (CT) is limited. Given the possibility of subsequent waves of the COVID-19 pandemic and the risk of excessive radiation exposure from CT, CXR may be used as a reliable alternative.