Lung ultrasound in children with pneumonia: inter-operator agreement on specific thoracic regions

Background: Chest x-rays are frequently performed in children with pneumonia. However, its great inter- and intra variability is a well-recognized problem. The main objective of this study was to evaluate the inter-operator agreement of lung ultrasonography (LUS) on specific thoracic regions in children diagnosed with pneumonia. Methods: Participants underwent LUS examinations performed by an expert and a novice operator. Cohen’s Kappa (κ) coefficient was used to measure strength of agreement between operators. LUS diagnoses were correlated with chest x-rays read by an independent pulmonologist. Results: A total of 261 thoracic regions were evaluated. The median age and weight of participants were 30 months (interquartile range = 5-41) and 11.6 (interquartile range = 7.2-17), respectively. A substantial overall agreement between operators was found for normal lung tissue [κ = 0.615, 95% confidence interval (95%CI) = 0.516-0.715] and for consolidations (κ = 0.635, 95%CI = 0.532-0.738). For interstitial syndrome, a moderate agreement was observed (κ = 0.573 95%CI = 0.475-0.671). An almost perfect agreement was found for pleural effusion (κ = 0.868, 95%CI = 0.754-0.982). The diagnosis of consolidations by LUS showed a high sensitivity (93% for both operators) but a low specificity (14% for expert and 25% for novice operator). In general, abnormal patterns were more often visualized by LUS than by chest x-rays. Conclusion: Even when performed by operators with very distinct degrees of experience, LUS had a good inter-operator reliability for detecting sonographic patterns on specific thoracic regions.