Pleural thickening: its significance and relationship to asbestos dust exposure.

The admission chest radiographs of 824 were screened for the presence of bilateral pleural thickening. Those patients with pleural thickening were scored according to the ILO classification of radiographs of the pneumoconioses. The prevalence of bilateral pleural thickening was high (6.2%) in these patients, of whom 67% had an environmental or occupational history suggestive of asbestos exposure. The predictive value of bilateral pleural thickening alone as an indicator of previous asbestos exposure was 67%. If one excludes known medical or surgical etiologies of pleural thickening then the predictive value increased to 81%. The radiographic detection of bilateral pleural thickening has a strong association with prior asbestos exposure.