Inter-reader variability in chest radiography and HRCT for the early detection of asbestos-related lung and pleural abnormalities in a cohort of 636 asbestos-exposed subjects.

PURPOSE

To compare inter-reader variability of chest X-ray and high resolution computed tomography (HRCT) scans of formerly asbestos-exposed employees over a 4-year period.

METHODS

In this longitudinal study, 636 formerly asbestos-exposed persons were annually examined with chest radiographs and HRCT scans. Ten observer pairs classified the radiographs and HRCT scans, using the ILO classification and a custom-made CT classification. Inter-observer variability was calculated using the kappa-coefficient.

RESULTS

Despite all expectations, HRCT inter-reader variability according to asbestos-related lung or pleura alterations at an early stage did not turn out to be better than X-ray inter-reader variability. Substantial inter-observer agreement was found for pleural calcifications (kappa(X-ray) = 0.63; kappa(CT) = 0.64). Averaging over kappa led to fair inter-observer agreement of both methods (kappa(X-ray) = 0.36; kappa(CT) = 0.34).

CONCLUSIONS

High resolution computed tomography scans are superior to X-rays in detecting lung alterations after asbestos exposure and are supposedly easier to interpret. Nevertheless, inter-observer variability did not differ between the two methods in this study. This was probably due to the only discrete asbestos-related lung or pleura alterations of this cohort and to the unfamiliar CT classification sheet, which was revised on the basis of the presented results.