Lung function predicts survival in a cohort of asbestos cement workers

Abstract

To study the predictive power of respiratory screening examinations a cohort of asbestos workers was followed from active work in an asbestos cement plant until death. From a cohort with data on individual exposure since first employment 309 workers who had a preventive medical examination in 1989/1990 were observed until death or the end of 2006. The impact of asbestos exposure (fibre years) and of smoking history on lung function was examined by linear regression, on specific causes of death and total mortality by Cox regression. The prognostic value of lung function, chest X-ray, and various clinical findings regarding total mortality was also examined by Cox regression. Lung function proved to be the best predictor of survival apart from current smoking. Depending on the lung function variable an impairment by the interquartile range resulted in a hazard ratio of 1.5-1.6 while for current smokers it was 2.3. An increase of 70 fibre years (interquartile range) led to a hazard ratio of only 1.1. Lung function was influenced by asbestos exposure, current (but not former) smoking, and by pathological X-ray findings. The risk for pleural mesothelioma was dominated by time since first exposure to crocydolite in the pipe factory while the risk for bronchial cancer increased with smoking and total fibre years. An unexpected finding was an increase of gastric cancer in asbestos cement workers. Lung function decrease predicts risk of premature death better than exposure history and regular spirometry should therefore be offered as primary screening to all former asbestos workers. In workers with a history of high cumulative exposure or rapid lung function decrease or radiological signs (diffuse pleural thickening or small irregular opacities) more sensitive techniques (high resolution computer tomography) need to be applied. All smokers with a history of asbestos exposure should be given free smoking cessation therapy to prevent premature death and lung cancer in particular.