Interobserver Variations in Diagnosing Asbestosis According to the ILO Classification

Inhalation of asbestos fibres leads to asbestosis of the pleura and the lung, with possible progression to lung cancer and malignant pleural or peritoneal mesothelioma. Asbestosis remains difficult to diagnose, especially in its early stages. The most important role in its diagnosis is that of chest radiographs. The aim of this cross-sectional study was to address interobserver variations in interpreting chest radiographs in asbestos workers, which remain to be an issue, despite improvements in the International Labour Office (ILO) classification system. In our ten-year study, we investigated 318 workers occupationally exposed to asbestos, and in 210 workers with diagnosed asbestos-related changes we compared interpretations of chest radiographs according to ILO by two independent radiologists. The apparent degree of interobserver variation in classifying lung fibrosis was 26.66% for the diameter of changes and 42.2% for the profusion of the changes. In cases with diffuse pleural thickening, the interobserver variation using ILO procedures was 34.93%. This investigation raises the issue of standardisation and objectivity of interpretation of asbestosis according to the ILO classification system. This study has revealed a significant disagreement in the estimated degree of pleural and parenchymal asbestos pulmonary disease. This is why we believe high-resolution computed tomography (HRCT) should also be used as a part of international classification.