Effect of tobacco smoking on the presence of asbestosis at postmortem and on the reading of irregular opacities on roentgenograms in asbestos-exposed workers

Our plain-English summary of Effect of tobacco smoking on the presence of asbestosis at postmortem and on the reading of irregular opacities on roentgenograms in asbestos-exposed workers, by E. Hnizdo, G.K. Sluis-Cremer (The American Review of Respiratory Disease, 1988).

The study

• Authors: E. Hnizdo, G.K. Sluis-Cremer
• Journal: The American Review of Respiratory Disease
• Published: 1988;138(5):1207-12
• Cited by: 27 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000228).

Abstract

A statistically significant association between cigarette smoking and radiologic readings of irregular opacities was observed in a case-control study of 430 South African asbestos miners (OR = 3.03; 95% confidence interval, 1.50; 6.11). In another case-control study of 487 dead South African asbestos miners, no positive association between smoking and autopsy findings for asbestosis was observed (OR = 0.50; 95% confidence interval, 0.20; 1.29). The association between greater than slight asbestosis (moderate and marked) and smoking (yes/no) was not significant (Fisher's exact test, p = 0.44), and the adjusted odds ratio was 1.25 with 95% confidence interval (0.20; 7.78). In addition, the certification in life for asbestosis, based on chest roentgenogram readings for irregular opacities, was also found to have a tendency to be related to smoking. Thus, the findings of these studies do not support the hypothesis that smoking is associated with the presence of asbestosis at autopsy or that smoking and asbestos dust act synergistically in producing asbestosis at autopsy. But the findings of this and other studies suggest that smoking does produce some change in the lung structure that can be visible on the roentgenogram and can be wrongly interpreted as irregular opacities caused by asbestosis.

In plain English

The authors carried out two case-control studies of South African asbestos miners. The first used autopsy records of 487 dead white miners drawn from a cohort of 7,309. After excluding 31 men lacking smoking data, 117 with asbestosis at autopsy were compared with 339 without it. No positive association was found between ever smoking and asbestosis at autopsy (odds ratio 0.50, 95% confidence interval 0.20 to 1.29). For moderate or marked asbestosis the odds ratio was 1.25 (0.20 to 7.78), which was not statistically significant. The second study compared 145 miners whose chest X-rays were read as showing irregular opacities (profusion 1/0 or more) with 285 age-matched miners whose films were read as 0/0 for irregular opacities. Smoking was significantly associated with these X-ray readings (odds ratio 3.03, 1.50 to 6.11, adjusted for asbestos fiber-years). The authors concluded their findings did not support a link between smoking and asbestosis at autopsy. They suggested smoking produces lung changes visible on X-rays that can be wrongly read as asbestosis. They added that a link with more severe asbestosis could not be completely excluded.

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: Two case-control studies: one of autopsy findings for asbestosis in dead miners, one of chest X-ray readings of irregular opacities in working miners
• Who was studied: Autopsy study: 487 white men who had worked in South African asbestos mines and had both annual medical examinations and an autopsy. They came from a mortality cohort of 7,309 white men employed between 1920 and 1981. After 31 men with missing smoking data were excluded, there were 117 cases with asbestosis and 339 controls. X-ray study: 145 cases with irregular opacities and 285 age-matched controls whose films were read as 0/0. They were selected from a survey of 2,245 men employed in South African asbestos mines on November 30, 1970, or who took up employment up to November 30, 1975. The article does not state the race of this second group.
• Exposure: Cigarette and pipe smoking, taken from medical examination records. Asbestos mining exposure was measured as cumulative fiber-years, based on long fiber counts for the mine, occupation and calendar year. Gold mining dust exposure was also considered. The article text does not specify fiber types for this analysis.
• Main results:
  • Autopsy study, any degree of asbestosis: the standardized odds ratio for ever smoked versus never smoked was 0.50, 95% confidence interval (0.20; 1.29).
  • Autopsy study: the proportion of subjects with any degree of asbestosis showed a slightly significant decrease as the level of smoking increased (p = 0.037).
  • Autopsy study, moderate and marked asbestosis (38 cases versus 339 controls): the standardized odds ratio for smoking (yes/no) was 1.25 (0.20; 7.78). The association was not significant (Fisher's exact test, p = 0.44).
  • Autopsy study: after control subjects who died of ischemic heart disease were excluded, the crude and standardized odds ratios for smoking and asbestosis were still not different from one.
  • X-ray study: the unadjusted Mantel-Haenszel odds ratio for smoking (yes/no) and irregular opacities was 2.20, 95% confidence interval (1.42; 3.75).
  • X-ray study: adjusted for asbestos fiber-years, the odds ratio for irregular opacities in smokers (all smoking categories combined) versus never smokers was 3.03, 95% confidence interval 1.50 to 6.11.
  • X-ray study: the proportion of subjects with irregular opacities increased significantly with increasing level of smoking (Mantel-Haenszel chi-square 8.8, p = 0.003).
  • Men certified in life for parenchymal asbestosis showed a slight tendency to be heavier smokers than men who were not certified (p = 0.10).
• The authors' conclusion: The authors concluded that the results do not support the hypothesis that smoking is associated with asbestosis at autopsy. They concluded that the results suggest smoking produces some changes in lung structure that can be seen on X-rays and wrongly interpreted as irregular opacities caused by asbestosis.
• Limitations the authors state:
  • Pack-years of smoking could not be calculated because there was no information on smoking habits before 1960.
  • The possibility that smoking is associated with the more severe degrees of asbestosis cannot be completely excluded.
  • Selection bias arising from links between causes of death and smoking cannot be completely excluded.
  • Black miners were not included in the autopsy study because of inadequate exposure data, erratic death certification and absence of smoking data.

Topics

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

Medical terms in this study, explained in our Lexicon: Case-Control Study, confidence interval, Autopsy, Odds Ratio.

Related studies

• Effect of tobacco smoking on the presence of asbestosis at postmortem and on the reading of irregular opacities on roentgenograms in asbestos-exposed workers — A. Kraut, J. Godbold, et al. (1989)
• Factors influencing the reading of small irregular opacities in a radiological survey of asbestos miners in South Africa — G.K. Sluis-Cremer, P.A. Hessel, et al. (1989)
• Cigarette smoking and small irregular opacities — W. Weiss (1991)
• Smoking and roentgenographic opacities in US Navy asbestos workers — A.M. Ducatman, B.F. Withers, et al. (1990)
• Progression of irregular opacities in asbestos miners — G.K. Sluis-Cremer, E. Hnizdo (1989)
• Irregular opacities in the lung, occupational asthma, and airways dysfunction in aluminum workers — K.H. Kilburn, R.H. Warshaw (1992)

Browse more research in The American Review of Respiratory Disease, or return to medical research.