The natural course of lung function decline in asbestos exposed subjects with pleural plaques and asbestosis

While there is a good knowledge of the natural course of lung function in interstitial lung diseases (ILD) like idiopathic lung fibrosis (IPF), many ambiguities remain in patients with asbestosis. Therefore, we evaluated the change in lung function in asbestos exposed subjects with pleural plaques and asbestosis and analysed corresponding morphology of computer tomography of the thorax.

93 asbestos exposed subjects with pleural plaques and asbestosis were analysed retrospectively at the Klinikum Bergmannsheil of the Ruhr-University of Bochum. Parameters of lung function were obtained at least twice and annual changes of FVC, TLC and DLCOsb were calculated. In addition, we assessed the predominant pattern in high-resolution computer tomography of the thorax (HRCT) and differentiated three phenotypes: p (pleural) -type, f (fibrosis) -type and m (mixed) -type.

FU data are available in 56/93 (60.2%) patients. The annual deterioration (Mean ± SEM) of FVC is -31.46 ± 17.34 ml, of TLC -55.55 ± 25.67 ml, of DLCOsb -0.38 ± 0.07 mmol/min/kPa and of DLCOva -0.05 ± 0.01 mmol/min/kPa/L. A categorical change of FVC > -100 ml was found in 12/56 (21.4%) and 18/56 (32.1%) patients showed an annual loss of TLC > -100 ml. The greatest annual decline of FVC was observed in patients with the fibrotic phenotype on HRCT (-76.76 ± 66.43 ml) and the mixed phenotype (-81.52 ± 24.79 ml), while the pleural phenotype was less affected (-10.52 ± 25.07 ml).

More than 20% of our cohort have a progressive disease with an annual loss of FVC > -100 ml. Patients with the fibrotic-phenotype or mixed-phenotype on HRCT are particularly at risk.