Objective: To assess the frequency of computed tomography (CT) scan pleural and interstitial changes in a population of urban transportation workers with low cumulative exposure to asbestos, and to measure inter-reader agreement.
Design: A total of 269 male volunteers (mean age 54.0 +/- 2.3 years, mean estimated cumulative exposure index 1.7 +/- 2.3 fibres/ml-years), underwent a CT scan which was read independently by three experienced readers, with further consensus reading in case of pleural or parenchymal abnormalities. Inter-reader agreement was assessed by means of Kappa statistic.
Results: On consensus reading, four subjects had interstitial opacities, three had diffuse pleural thickening and 26 (9.7%) had pleural plaques that were unilateral in 65% of cases and < or =2 mm thick in 54% of cases. No correlation was observed between pleural plaques and latency, duration of exposure or cumulative exposure. The inter-reader agreement for the detection of pleural abnormalities was fair.
Conclusion: In this relatively young population with low cumulative exposure to asbestos, the prevalence of pleural abnormalities was low. These abnormalities were very limited in thickness and extent, leading to marked inter-reader variability and making it difficult to assess their relationship to asbestos exposure.