Early detection of interstitial lung disease in asbestos exposed non-smoking workers by mid-expiratory flow rate and high resolution computed tomography

Abstract

Ten years of lung function and radiological findings in six non-smoking asbestos exposed subjects who had increased mid-expiratory flow rate (FEF(25-75%)) as the only functional abnormality were prospectively analysed. A biphasic change in FEF(25-75%) was noted. It initially increased up to the fifth year, and then a decrease was seen. In the final three years of the study, FEF(25-75%) reduction correlated well with a decrease in pulmonary capacity for CO (DLCO). During that time high resolution computed tomography (HRCT) probability scores correlated inversely with FEF(25-75%) and with DLCO, whereas chest radiography was unchanged (International Labour Organisation (ILO) profusion below 1/1). For five of the six subjects HRCT probability of asbestosis was intermediate. An increase in FEF(25-75%) in some asbestos exposed non-smoking workers may be one of the earliest functional signs indicative of future development of parenchymal asbestosis. Early asbestos related parenchymal abnormalities are seen more frequently on HRCT than on chest radiography.