Between- and within-reader variability in the assessment of pleural abnormality using the ILO 1980 international classification of pneumoconioses.

Although there are published data concerning reader variability in the assessment of parenchymal pneumoconiotic changes using the ILO Classification of Radiographs, nothing has been published on reader variability with regard to pleural abnormalities. Therefore, in the context of an epidemiologic study, we assessed between- and within-reader variability in the reading of chest radiographs for pleural abnormality using the ILO 1980 International Classification of Radiographs of Pneumoconioses. Chest radiographs of 182 insulation workers interspersed with 24 subjects without documented exposure to asbestos were assembled and read blindly by two readers, reading separately on two occasions, 1 week apart. The results of this study suggest that confident separation of pleural plaques and diffuse pleural thickening may be difficult to achieve using the present guidelines of the ILO 1980 classification. In the evaluation of the width of chest wall pleural abnormality, within-reader agreement improves as the width increases, while between-reader agreement was much less satisfactory. Excellent agreement is obtained in the evaluation of other sites, especially costophrenic angle obliteration and the presence of pleural calcification.