Validation of clinical criteria for diagnosing asbestosis in asbestos-cement workers

The recently developed diagnostic criteria for asbestosis, including chest x-ray abnormalities and respiratory impairment consistent with interstitial lung fibrosis, were tested in 550 current asbestos-cement workers. The findings showed the correlation of x-ray ILO/UC scores for small irregular opacities (s, t, u) with duration of exposure, especially evident in relation to category of 1/2 and above ("cutoff category") detected in 48 subjects. An increasing x-ray score was accompanied by more functional abnormality, demonstrated by a restrictive defect in ventilation, followed by a fall in arterial oxygen pressure on exercise and impaired diffusing capacity. Amongst subjects working for at least 10 years, thirty met the roentgenographic and functional criteria for asbestosis. On the basis of these criteria, asbestosis could be diagnosed only in one subject employed for not longer than 5 years and two others working for not longer than 9 years, which can be explained by a false--positive effect.