Restrictions of VC and DLCO in relation to asbestos-related computed tomographic findings quantified by ICOERD-based parameters

Our plain-English summary of Restrictions of VC and DLCO in relation to asbestos-related computed tomographic findings quantified by ICOERD-based parameters, by L. Ströker, K. Peldschus, R. Herold, et al (BMC Pulmonary Medicine, 2022).

The study

• Authors: L. Ströker, K. Peldschus, R. Herold, V. Harth, A.M. Preisser
• Journal: BMC Pulmonary Medicine
• Published: 2022;22(1):236
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Even almost 30 years after the ban on the use of asbestos in Germany, the effects of asbestos are still highly relevant in everyday clinical practice in occupational medicine. The aim of this study was to further investigate the significance of essential parameters of both pulmonary function diagnostics and imaging techniques (low-dose HR-TCT) for the prevention and early detection of asbestos-related morphological and functional lung changes.

Methods: Data from spirometry, body plethysmography and diffusion capacity, as well as CT images of the thorax, were retrospectively studied from 72 patients examined between 2017 and 2019 at the Institute for Occupational and Maritime Medicine (ZfAM), Hamburg, Germany. The subjects were divided into four subgroups according to the presence of comorbidities (concomitant cardiac diseases, obstructive ventilatory disorder, pulmonary function pattern consistent with emphysema, and no other pulmonary or cardiac diseases). These subgroups were analysed in addition to the overall collective. The CT images were evaluated according to the International Classification of Occupational and Environmental Respiratory Diseases (ICOERD) with radiological expertise. In addition, some asbestos-related parameters were newly quantified, and corresponding scores were defined based on ICOERD. Statistical analysis included the use of correlations and fourfold tables with calculation of Spearman's rho (ρ), Cohen's κ, and accuracy.

Results: Vital capacity (VC) is slightly reduced in the total collective compared to the normal population (mean 92% of predicted value), while diffusion capacity for CO (DLCO) shows predominantly pathological values, mean 70% of the respective predicted value. The CO transfer coefficient (DLCO/VA), which refers to alveolar volume (VA), also shows slightly decreased values (mean 87% pred.). Seventy-nine percent of patients (n = 57) had signs of pulmonary fibrosis on CT scans, and pleural plaques appeared in 58 of 72 patients (81%). Of the newly quantified additional parameters, particularly frequently described findings are subpleural curvilinear lines (SC, n = 39) and parenchymal bands (PB, n = 29). VC correlates well with the expression of pleural plaques (ρ = - 0.273, P < 0.05), and DLCO measures show a better correlation with fibrosis score (ρ = - 0.315, P < 0.01). A third, newly developed score, which includes the extent of pleural plaques and additional subpleural parameters instead of fibrosis parameters, shows significant correlations for both VC and DLCO (ρ = - 0.283, - 0.274, resp.; both P < 0.05).

Discussion: The importance of spirometry (VC) and diffusion capacity measurement (DLCO) as essential diagnostic procedures for the early detection of asbestos-related changes ‒ also including patients with relevant concomitant cardiac or pulmonary diseases ‒ was confirmed. Significant and better correlations between lung function changes (VC and DLCO) and abnormal CT findings are seen when parenchymal bands (PB), subpleural curvilinear lines (SC), and rounded atelectasis (RA) are quantitatively included into the evaluation, in addition to assessing the extent of pleural plaques alone. Therefore, when assessing CT images according to ICOERD, these parameters should also be quantified.

© 2022. The Author(s).

In plain English

This retrospective study looked at 72 men who had formerly been exposed to asbestos at work and were examined between 2017 and 2019 at the Institute for Occupational and Maritime Medicine in Hamburg, Germany. They had worked in 22 different occupations, most often as locksmiths, automotive mechanics and electricians. Their asbestos dose was not recorded. The authors compared breathing tests with low-dose high-resolution CT scans, which were scored with the ICOERD classification. They also tested a new score (Score C) that adds parenchymal bands, subpleural curvilinear lines and rounded atelectasis to the pleural plaque score. On CT, 57 of the 72 men had signs of pulmonary fibrosis and 58 had pleural plaques. A greater extent of pleural plaques was linked with lower vital capacity (correlation −0.273, P less than 0.05). More fibrosis was linked with lower carbon monoxide diffusion capacity (correlation −0.315, P less than 0.01). Score C correlated with both measures. The authors concluded that CT changes, even when limited, related to lung function. They named as limitations the use of a single radiologist, the many smokers, and small subgroups.

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: Retrospective analysis of clinical records (lung function tests and CT scans), with correlation and fourfold-table statistics
• Who was studied: 72 men formerly exposed to asbestos, examined 2017 to 2019 at the Institute for Occupational and Maritime Medicine (ZfAM), Hamburg, Germany. Of 77 patients, 5 were excluded for incomplete records or missing CT data; the only woman was among those excluded.
• Exposure: Occupational asbestos exposure in 22 occupations, most commonly locksmith (n = 12), automotive mechanic (n = 10) and electrician (n = 8). Fiber type is not reported, and the asbestos dose was not recorded.
• Main results:
  • In the whole group, mean vital capacity was 92% of the predicted value.
  • In the whole group, mean DLCO (diffusion capacity for carbon monoxide, measured in 69 patients) was 70% of the predicted value.
  • On CT, 57 of the 72 patients had findings indicating pulmonary fibrosis (fibrosis score of 2 or more).
  • 58 of the 72 patients had pleural plaques.
  • Of the newly quantified additional findings, subpleural curvilinear lines (n = 39) and parenchymal bands (n = 29) were the most common.
  • In the whole group, the extent of pleural plaques correlated with lower vital capacity (rho = −0.273, P less than 0.05).
  • In the whole group, the fibrosis score correlated with lower DLCO (rho = −0.315, P less than 0.01).
  • In the whole group, the correlation between vital capacity and the fibrosis score was not statistically significant (rho = −0.168).
  • Only 16 of 72 patients had a vital capacity below the lower limit of normal. 43 patients had CT signs of fibrosis with a normal vital capacity.
  • The new Score C (pleural plaques plus parenchymal bands, subpleural curvilinear lines and rounded atelectasis) correlated with vital capacity (rho = −0.283, P less than 0.05).
  • Score C also correlated with DLCO (rho = −0.274, P less than 0.05).
  • The transfer coefficient (DLCO/VA) showed no relevant correlation with Score C (rho = 0.024, not significant).
  • Patients in the subgroup with lung function or CT findings indicating emphysema had the lowest diffusion capacity (mean 59% of predicted).
• The authors' conclusion: The authors concluded that even the partly limited asbestos-related CT changes in their cohort were related to changes in lung function. They recommended measuring vital capacity and DLCO, and quantifying the additional subpleural ICOERD findings (parenchymal bands, subpleural curvilinear lines, rounded atelectasis).
• Limitations the authors state:
  • All CT scans were read by one radiologist, and no second reader reviewed them.
  • Many patients were smokers or ex-smokers, and smoking-related CT changes may be hard to tell apart from mild asbestos-related fibrosis.
  • The patient group was small, so splitting it into subgroups gave partly non-significant results and may preclude firm conclusions.
  • Some patients were assigned to more than one subgroup.

Topics

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

Medical terms in this study, explained in our Lexicon: Diffusing Capacity (DLCO), Spirometry, Thorax, Emphysema, Pulmonary Fibrosis, CT Scan, Pleural Plaques, Subpleural Curvilinear Line.

Related studies

• Computed tomographic findings of environmental asbestos-related malignant pleural mesothelioma — U.M. Yilmaz, G. Utkaner, et al. (1998)
• Relations between vital capacity, CO diffusion capacity and computed tomographic findings of former asbestos-exposed patients: a cross-sectional study — A.M. Preisser, K. Schlemmer, et al. (2020)
• Overall survival of pseudomyxoma peritonei and peritoneal mesothelioma patients after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy can be predicted by computed tomography quantified sarcopenia — A. Galan, P. Rousset, et al. (2018)
• Asbestos-related lesions of the pleura: parietal plaques compared to diffuse thickening studied with chest roentgenography, computed tomography, lung function, and gas exchange — G. Hillerdal, P. Malmberg, et al. (1990)
• Agreement between chest radiography and high-resolution computed tomography in diagnosing dust-related interstitial lung fibrosis — R.R. Tiwari (2015)
• Comparison of x-ray films and low-dose computed tomographic scans: demonstration of asbestos-related changes in 2760 nuclear weapons workers screened for lung cancer — A. Miller, S.A. Widman, et al. (2013)

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