Comparative Diagnostic Accuracy of Lung Ultrasound and Chest XRay for Early Detection of Pneumonia in Emergency Settings

Abstract

Background: Pneumonia is a major cause of morbidity and mortality worldwide, requiring prompt and accurate diagnosis, especially in emergency settings. Chest X-ray (CXR) is traditionally used for diagnosis; however, it has limitations in early detection. Lung ultrasound (LUS) has emerged as a rapid, bedside imaging modality with promising diagnostic accuracy. Objective: To compare the diagnostic accuracy of lung ultrasound and chest X-ray in the early detection of pneumonia in patients presenting to the emergency department. Methods: This prospective cross-sectional study was conducted at Department of Pulmonology, Liaquat University of Medical & Health Sciences     (LUMHS), Jamshoro, from January 2023 to December 2023. A total of 180 adult patients with clinical suspicion of pneumonia were enrolled. All patients underwent both LUS and CXR within 6 hours of presentation. The final diagnosis was established using a composite clinical reference standard including clinical, laboratory, microbiological findings, and response to treatment. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy were calculated for both modalities. Results: Out of 180 patients, pneumonia was confirmed in 124 (68.9%) cases. Lung ultrasound showed sensitivity of 95.2%, specificity of 80.0%, PPV of 90.8%, NPV of 88.9%, and overall accuracy of 92.2%. Chest X-ray demonstrated sensitivity of 79.0%, specificity of 75.9%, PPV of 87.5%, NPV of 62.0%, and accuracy of 78.9%. The difference in sensitivity between the two modalities was statistically significant (p ? 0.001). Receiver operating characteristic analysis showed superior performance of LUS (AUC 0.91) compared to CXR (AUC 0.77). Conclusion: Lung ultrasound is a highly sensitive and accurate modality for early detection of pneumonia and outperforms chest X-ray in emergency settings. It can be used as a reliable first-line or complementary diagnostic tool, particularly in resource-limited environments. Further multicenter studies are recommended to support its widespread implementation.