Restrictive lung function and asbestos-induced pleural fibrosis. A quantitative approach

Our plain-English summary of Restrictive lung function and asbestos-induced pleural fibrosis. A quantitative approach, by D.A. Schwartz, J.R. Galvin, S.J. Yagla, et al (The Journal of Clinical Investigation, 1993).

The study

• Authors: D.A. Schwartz, J.R. Galvin, S.J. Yagla, S.B. Speakman, J.A. Merchant, G.W. Hunninghake
• Journal: The Journal of Clinical Investigation
• Published: 1993;91(6):2685-92
• Cited by: 29 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

To assess further the clinical significance of asbestos-induced pleural fibrosis, we used a computer algorithm to reconstruct images three dimensionally from the high-resolution computerized tomography (HRCT) scan of the chest in 60 asbestos-exposed subjects. Pulmonary function tests, chest radiographs, and HRCT scans were performed on all study subjects. The volume of asbestos-induced pleural fibrosis was computed from the three-dimensional reconstruction of the HRCT scan. Among those with pleural fibrosis identified on the HRCT scan (n = 29), the volume of the pleural lesion varied from 0.01% (0.5 ml) and 7.11% (260.4 ml) of the total chest cavity. To investigate the relationship between asbestos-induced pleural fibrosis and restrictive lung function, we compared the computer-derived estimate of pleural fibrosis to the total lung capacity and found that these measures were inversely related (r = -0.40; P = 0.002). After controlling for age, height, pack-years of cigarette smoking, and the presence of interstitial fibrosis on the chest radiograph, the volume of pleural fibrosis identified on the three-dimensional reconstructed image from the HRCT scan was inversely associated with the total lung capacity (P = 0.03) and independently accounted for 9.5% of the variance of this measure of lung volume. These findings further extend the scientific data supporting an independent association between pleural fibrosis and restrictive lung function.

In plain English

This University of Iowa study examined 60 men who had been occupationally exposed to asbestos for at least one year in a high-exposure setting, with at least 20 years since first exposure. Most were identified through a 1986 national screening program for sheet metal workers. Each had lung function tests, a chest X-ray and a high-resolution CT (HRCT) scan. The authors used computer programs to build three-dimensional images from the scans and to measure the volume of asbestos-induced pleural fibrosis, which is scarring of the lining around the lungs. HRCT showed pleural fibrosis in 29 men, with volumes from 0.5 to 260.4 ml. A larger volume of pleural fibrosis went with a lower total lung capacity (r = -0.40; P = 0.002). After allowing for age, height, smoking and X-ray signs of interstitial fibrosis, this link remained statistically significant. Each ml of pleural fibrosis was associated with a 5-ml decrease in total lung capacity. The link with diffusing capacity was not statistically significant. The authors concluded that the findings support an independent association between pleural fibrosis and restrictive lung function.

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: Study of asbestos-exposed workers using computer three-dimensional reconstruction of HRCT scans, compared with lung function tests and chest radiographs
• Who was studied: 60 asbestos-exposed subjects, mainly from the Sheet Metal Workers' 1986 National Screening Program and some from the University of Iowa Occupational Medicine Clinic. All were men, 98% were white, and the mean age was 60.0 years. People with asbestosis or pleural disease were preferentially invited to take part.
• Exposure: Occupational asbestos exposure for at least 1 year in a high-exposure setting (direct contact with asbestos), with at least 20 years between first exposure and entry into the study. Fiber types were not specified.
• Main results:
  • HRCT identified pleural fibrosis in 29 of the 60 subjects. The computer-estimated volume of the pleural lesions ranged from 0.5 to 260.4 ml.
  • The computer-derived volume of pleural fibrosis was inversely related to total lung capacity (r = -0.40; P = 0.002).
  • In a model with pleural fibrosis volume as the only independent variable, pleural fibrosis was significantly associated with total lung capacity (regression coefficient = -5.30; P = 0.017). It accounted for 9.5% of the variance in total lung capacity.
  • After controlling for age, height, interstitial fibrosis on the chest radiograph and pack-years of smoking, pleural fibrosis volume remained inversely related to total lung capacity. Each ml of pleural fibrosis was independently associated with a 5-ml decrease in total lung capacity.
  • Among the chest X-ray groups, total lung capacity and forced vital capacity tended to be lower in those with pleural disease.
  • The relationship between pleural fibrosis volume and the diffusing capacity of carbon monoxide was marginal and not statistically significant. No clear relationship was found with residual volume.
• The authors' conclusion: The authors concluded that their findings further extend the scientific data supporting an independent association between pleural fibrosis and restrictive lung function. They also stated that their results support a dose-response relationship between the amount of pleural fibrosis and the decrease in lung volume.
• Limitations the authors state:
  • The authors indicated that caution should be used in applying these findings, obtained in a cohort of asbestos-exposed workers, to individual patients. The passage is partly garbled in the scanned text.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Pleural plaques and thickening.

Medical terms in this study, explained in our Lexicon: Restrictive Lung Disease, Fibrosis, High-Resolution CT (HRCT), Pulmonary Function Test (PFT), Chest X-Ray, Total Lung Capacity (TLC), Interstitial Fibrosis.

Related studies

• Determinants of restrictive lung function in asbestos-induced pleural fibrosis — D.A. Schwartz, J.R. Galvin, et al. (1990)
• Asbestos-induced pleural fibrosis and impaired lung function — D.A. Schwartz, L.J. Fuortes, et al. (1990)
• Do asbestos-related pleural plaques on HRCT scans cause restrictive impairment in the absence of pulmonary fibrosis? — B. Clin, C. Paris, et al. (2011)
• Determinants of restrictive lung function in asbestos-induced pleural fibrosis — C.J. Bergin (1991)
• Comparative quantitative evaluation of pleural fibrosis and its effects on pulmonary function in two large asbestos-exposed occupational groups--insulators and sheet metal workers — R. Lilis, A. Miller, et al. (1992)
• Pulmonary function and pleural fibrosis: quantitative relationships with an integrative index of pleural abnormalities — R. Lilis, A. Miller, et al. (1991)

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