Lung function predicts survival in a cohort of asbestos cement workers

Our plain-English summary of Lung function predicts survival in a cohort of asbestos cement workers, by H. Moshammer, M. Neuberger (International Archives of Occupational and Environmental Health, 2009).

The study

• Authors: H. Moshammer, M. Neuberger
• Journal: International Archives of Occupational and Environmental Health
• Published: 2009;82(2):199-207
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Purpose: 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.

Methods: 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.

Results: 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.

Conclusion: 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.

In plain English

This cohort study followed 309 workers (270 men, 39 women) from an Upper Austrian asbestos cement factory. All had a medical check-up in 1989/1990 and were followed until death or the end of 2006. Most had been exposed to chrysotile only. Pipe factory workers were also exposed to amphibole asbestos, mainly crocidolite. By the end of 2006, 82 workers had died, seven from pleural mesothelioma and six from bronchial carcinoma. Poorer lung function at the check-up, current smoking and higher cumulative asbestos exposure were each associated with shorter life. No X-ray finding was a statistically significant predictor of life expectancy in this cohort. Lung cancer death was associated with higher cumulative exposure, and none of the 137 never-smokers died of bronchial carcinoma. Mesothelioma death was associated with amphibole exposure, while its association with cumulative exposure was not statistically significant. Stomach cancer deaths rose with exposure, but the authors noted this rested on few cases and needs confirmation. The authors concluded that early signs such as pleural thickening and lung function decrease predict premature death better than exposure history, and they recommended screening former asbestos workers.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Historical prospective cohort study; the workers screened in 1989/1990 were followed for mortality until the end of 2006
• Who was studied: 309 workers (270 males, 39 females) from the original cohort of the asbestos cement factory in Vöcklabruck, Upper Austria, who had a check-up in 1989/1990 and whose vital status was followed until the end of 2006
• Exposure: Mostly chrysotile only. Work in the pipe factory also involved amphibole asbestos, mainly crocidolite. Cumulative exposure was measured in fibre years; smoking history was recorded as never, former or current.
• Main results:
  • Of the 309 workers, 227 were alive and 82 had died by the end of 2006 (cause of death established for 80)
  • Deaths included seven pleural mesotheliomas and six bronchial carcinomas
  • Total life expectancy model: decreased FEV1 per interquartile range (0.85 l) had a hazard ratio of 1.72 (95% CI 1.25 to 2.37)
  • Total life expectancy model: decreased MEF50 per interquartile range (2 l/s) had a hazard ratio of 1.48 (95% CI 1.03 to 2.14)
  • Total life expectancy model: current smokers compared with non-smokers had a hazard ratio of 2.29 (95% CI 1.23 to 4.26)
  • Total life expectancy model: each 70 fibre years of asbestos exposure had a hazard ratio of 1.13 (95% CI 1.01 to 1.26)
  • No X-ray finding (nor blood pressure, liver enzymes, alcohol, glucose or blood lipids) was a statistically significant predictor of life expectancy in this cohort
  • Lung cancer mortality increased significantly with fibre years even after adjusting for smoking and amphibole exposure
  • No never-smoker was recorded with bronchial carcinoma as a cause of death: the deaths occurred in 3 of 53 current smokers, 3 of 120 former smokers and 0 of 137 never-smokers
  • Mesothelioma (7 deaths): amphibole exposure had a hazard ratio of 6.98 (95% CI 1.23 to 39.47)
  • Mesothelioma occurred also in non-smokers after amphibole exposure and a latency of 38 to 73 years
  • The influence of fibre years on mesothelioma was not statistically significant
  • Digestive tract cancer risk increased with asbestos exposure, mainly through stomach cancer (4 gastric cancer deaths), not peritoneal mesothelioma
  • Fibre years were associated with reduced FVC, FEV1 and MEF25
  • Pleural thickening was associated with reduced FVC and FEV1
  • Effects on lung function were seen in current smokers but not in former smokers
  • No death had asbestosis as its underlying cause
• The authors' conclusion: The authors concluded that screening of former asbestos workers should be recommended, because early signs such as pleural thickening and lung function decrease predict premature death better than exposure history. They also stated that smoking cessation is the only primary prevention of lung cancer in former asbestos workers.
• Limitations the authors state:
  • The gastric cancer finding is based on few cases and needs confirmation from other studies
  • No information was available on the main risk factors for gastric cancer
  • Small numbers, especially for specific diagnoses, reduce the study's power
  • Smoking history was a crude measure (never, former or current smoker)
  • Pathological X-ray findings had to be grouped as a single yes/no variable because there were few cases
  • Reverse causation (people stopping smoking because of symptoms) may play a role in some instances

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Asbestos Exposure, Chest X-Ray, Hazard Ratio, Pleural Mesothelioma, Stomach Cancer, Exposure History, Spirometry.

Related studies

• Survival in cohorts of asbestos cement workers and controls — M. Albin, V. Horstmann, et al. (1996)
• Radiographic changes and lung function in relation to activity of the glutathione transferases theta and mu among asbestos cement workers — K. Jakobsson, A. Rannug, et al. (1995)
• Absence of radiographic asbestosis and the risk of lung cancer among asbestos-cement workers: Extended follow-up of a cohort — M.M. Finkelstein (2010)
• Regarding "absence of radiographic asbestosis and the risk of lung cancer among asbestos-cement workers: extended follow-up of a cohort", by Murray Finkelstein, American Journal of Industrial Medicine 2010 — R.M. Ross (2011)
• Mortality in a cohort of cement workers in a plant of Central Italy — F. Giordano, V. Dell'orco, et al. (2012)
• Lung function predicts mortality: 10-year follow-up after lung cancer screening among asbestos-exposed workers — T. Vehmas, P. Pallasaho, et al. (2013)

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