Observer agreement in the diagnosis of interstitial lung diseases

Introduction: The density of radiologists per inhabitant is 7.5/100 thousand in the United Kingdom; in Brazil, it is 6.2, and in some areas, 1.5. Thoracic Radiologists are even scarcer. Pulmonologists frequently diagnose features associated with pulmonary fibrosis. Objective: To determine the interobserver agreement in diagnosing features associated with interstitial lung diseases. Methods: 63 chest CTs of covid-19 outpatients discharged from public hospitals of Curitiba/PR/Brazil from June 2020 to December 2021 were evaluated by an experienced pulmonologist and a thoracic radiologist. Each chest CT was assessed for the following characteristics: presence or absence of traction bronchiectasis and parenchymal bands in any lung lobe, independent of the severity, and qualitative visual evaluation was used to determine the extension of GGO, characterized: mild (1%–24%), moderate (25%–49%), severe (50–74%); very severe (≥ 75%). In addition, interobserver agreement for two observers in overall image quality or CT features was determined for a nonparametric Cohen´s Kappa test. Results: Traction bronchiectasis was identified for the thoracic radiologist in 14 (22.2%) and parenchymal bands in 38 (60.3%) CT, for the pulmonologist in 9 (14.3%), 32 (50.8%), respectively. The kappa agreement of traction bronchiectasis between professionals was 0,632 (p=<0.001), interpreted as substantial, for parenchymal bands was k=0.49 (p<0.001), with a moderate agreement. On the Other hand, extension GGO had no agreement (k=0.221; p= 0.001). Conclusions: Interobserver agreement in the diagnosis of traction bronchiectasis, the main feature associated with pulmonary fibrosis, was substantial.