Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques

Our plain-English summary of Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques, by J. Ameille, M. Matrat, C. Paris, et al (American Journal of Industrial Medicine, 2004).

The study

• Authors: J. Ameille, M. Matrat, C. Paris, N. Joly, C. Raffaelli, P. Brochard, Y. Iwatsubo, J.C. Pairon, M. Letourneux
• Journal: American Journal of Industrial Medicine
• Published: 2004;45(3):289-96
• Cited by: 15 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: In the literature, the criteria used to define pleural plaques (PP) and diffuse pleural thickening (DPT) are very heterogeneous and often imprecise. A multicenter restropective study was conducted to assess the relevance of two radiographic definitions of DPT.

Methods: The study population consisted of 287 subjects with asbestos-related pleural thickening. Two definitions were used to characterize DPT on postero-anterior chest radiographs: definition 1: pleural thickening associated with obliteration of the costophrenic angle; definition 2: pleural thickening at least 5 mm wide, extending for more than one quarter of the chest wall. Prevalence of respiratory symptoms and pulmonary function tests were compared in the DPT and PP groups resulting from the two definitions of DPT.

Results: According to definition 1, 34 patients (11.8%) were classified in the DPT group. Prevalence of chronic sputum, dyspnea, and chest pain was significantly higher in this group than in the PP group. FEV(1), FVC, and TLC were significantly lower. The differences persisted after adjustment for confounding factors. According to definition 2,102 patients (36.6%) were classified in the DPT group. DPT and PP groups did not differ in terms of prevalence of respiratory symptoms, or pulmonary function tests. Agreement between readers was significantly better when using definition 1.

Conclusions: Obliteration of costophrenic angle is a much more reliable sign than dimensional criteria to characterize DPT.

Copyright 2004 Wiley-Liss, Inc.

In plain English

This French study reviewed the records of 365 consecutive people referred in 1992 to 1994 to five occupational medicine departments, in the Paris area and Normandy, for suspected asbestos-related pleural fibrosis. The authors analyzed 287 people whose pleural thickening was confirmed on high-resolution CT. Most had worked making asbestos-containing products. The authors compared two chest X-ray definitions for telling diffuse pleural thickening apart from pleural plaques. Definition 1 was thickening joined to obliteration of the costophrenic angle. Under it, 34 people had diffuse thickening. They reported chronic sputum, exertional dyspnea and chest pain significantly more often than the plaque group and had significantly lower lung function, even after adjustment. Definition 2 was thickening at least 5 mm wide covering more than a quarter of the chest wall. Under it, 102 people had diffuse thickening. Their symptoms, chest pain and lung function did not differ significantly from the plaque group, though the group had more men, higher body mass index, and more smokers and ex-smokers. All three readers agreed in 87.1% of cases with definition 1 and 54.4% with definition 2. The authors concluded that costophrenic angle obliteration is a much more reliable sign than size criteria.

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: Multicenter retrospective study comparing two chest X-ray definitions of diffuse pleural thickening (DPT) against symptoms and lung function, with high-resolution CT (HRCT) used to confirm pleural thickening
• Who was studied: 365 consecutive subjects referred between 1992 and 1994 to occupational medicine departments in the Paris area (three centers) and Normandy (two centers), France, for suspected asbestos-related pleural fibrosis. 73 were excluded: 55 had no pleural thickening on HRCT and 18 had poor-quality X-rays. 287 were analyzed (88% men, mean age 58 years).
• Exposure: Occupational asbestos exposure; fiber types not specified. Jobs: manufacture of asbestos-containing products 69.7%, shipyards 6.2%, insulation 5.0%, welding 4.1%, other 15.0%. The Normandy patients were mainly former workers of one asbestos textile and friction material factory. Mean exposure duration was 25 years. Mean cumulative exposure for the 152 Normandy subjects was estimated at 255 f/ml.yrs.
• Main results:
  • With definition 1 (pleural thickening with obliteration of the costophrenic angle), 34 of 287 subjects (11.8%) were classed as DPT and 253 (88.2%) as pleural plaques (PP).
  • Under definition 1, these symptoms were significantly more common in the DPT group than in the PP group: chronic sputum 35.3% vs 18.8%, exertional dyspnea 54.6% vs 34.5%, and chest pain 42.4% vs 18.5%. The differences persisted after adjustment for age, sex and tobacco consumption.
  • Under definition 1, lung function (percent predicted) was significantly lower in the DPT group than in the PP group (p less than 0.001): FVC 81.1 vs 96.1, FEV1 75.5 vs 94.5, TLC 80.5 vs 92.2. The differences persisted after adjustment for tobacco consumption and BMI.
  • After excluding the 59 subjects whose HRCT suggested asbestosis, the definition 1 DPT group (n=23) still had significantly more chest pain than the PP group (n=205): 45.5% vs 19.2%. FVC (83.8 vs 96.1), FEV1 (75.9 vs 94.6) and TLC (80.9 vs 92.6) were still significantly lower, even after adjustment.
  • Under definition 1, mean cumulative exposure was higher in the DPT group than in the PP group: 323 vs 249 f/ml.yrs, measured in 13 DPT and 139 PP subjects. The difference was not statistically significant.
  • With definition 2 (thickening at least 5 mm wide extending over more than one quarter of the chest wall), 102 of 287 subjects were classed as DPT. Symptoms and lung function impairment were slightly greater in this DPT group than in the PP group, but the differences were not statistically significant. This was also true after excluding subjects with HRCT signs of asbestosis.
  • Under definition 2, the DPT group differed from the PP group in sex ratio, BMI and tobacco consumption (each p less than 0.05 in Table III). The DPT group had more men (94.1% vs 84.9%), higher mean BMI (27.3 vs 26.4), and more smokers and ex-smokers. The two groups did not differ in the characteristics of asbestos exposure.
  • Full agreement among the three readers was reached in 250 of 287 cases (87.1%) with definition 1 and in 156 cases (54.4%) with definition 2 (P less than 0.001).
  • Of the 102 subjects classed as DPT under definition 2, 83 (81.3%) were classed as PP under definition 1.
• The authors' conclusion: The authors concluded that, if the term DPT is used only when fibrosis of the visceral pleura is suspected, obliteration of the costophrenic angle on postero-anterior chest X-ray is a much more reliable sign of DPT than dimensional criteria. They also stated that distinguishing DPT from PP matters because DPT was associated with a high prevalence of chest pain and significant lung function impairment.
• Limitations the authors state:
  • The authors acknowledged that diagnosing DPT by obliteration of the costophrenic angle might underdiagnose it. They noted that CT or HRCT has shown visceral pleural fibrosis can occur without obliteration of the angle.

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: Asbestos-Related Pleural Disease, Diffuse Pleural Thickening, Pleural Plaques, Pleural Thickening, Chest X-Ray, Costophrenic angle, Pulmonary Function Test (PFT), Sputum.

Related studies

• 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)
• Do asbestos-related pleural plaques on HRCT scans cause restrictive impairment in the absence of pulmonary fibrosis? — B. Clin, C. Paris, et al. (2011)
• Asbestos-related diffuse pleural thickening — N. Fujimoto, K. Kato, et al. (2014)
• 3-Dimensional Quantification of Composite Pleural Plaque Volume in Patients Exposed to Asbestos Using High-resolution Computed Tomography: A Validation Study — G. Dournes, A. Dubois, et al. (2019)
• Asbestosis, pleural plaques and diffuse pleural thickening: three distinct benign responses to asbestos exposure — P.A. Gevenois, V. de Maertelaer, et al. (1998)
• Pleural plaques and asbestosis: dose- and time-response relationships based on HRCT data — C. Paris, S. Thierry, et al. (2009)

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