Asbestos-related diffuse pleural thickening

Our plain-English summary of Asbestos-related diffuse pleural thickening, by N. Fujimoto, K. Kato, I. Usami, et al (Respiration; International Review of Thoracic Diseases, 2014).

The study

• Authors: N. Fujimoto, K. Kato, I. Usami, F. Sakai, T. Tokuyama, S. Hayashi, K. Miyamoto, T. Kishimoto
• Journal: Respiration; International Review of Thoracic Diseases
• Published: 2014;88(4):277-84
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: The clinical features of asbestos-related diffuse pleural thickening (DPT) remain unclear.

Objectives: To clarify the association between radiological findings of DPT and respiratory function.

Methods: Medical data from patients with asbestos-related DPT were collected, including their history of occupational or neighborhood asbestos exposure, initial symptoms, modified Medical Research Council dyspnea grade, smoking history, radiological findings, and respiratory function test results.

Results: There were 106 DPT patients between 2005 and 2010 [i.e. 103 men (97.2%) and 3 women (2.8%)]. The median age at diagnosis was 69 years (range 46-88). Patient occupations related to asbestos exposure included: asbestos product manufacturing (n = 17); the shipbuilding industry (n = 14); the construction industry (n = 13); heat insulation work (n = 12); plumbing, asbestos spraying, and electrical work (n = 7 each), and transportation and demolition work (n = 4 each). The median duration of asbestos exposure was 25 years (range 2-54), and the median latency period before the onset of DPT was 46 years (range 25-66). Involvement of the costophrenic angle (CPA) was also negatively correlated with the percent vital capacity (%VC; r = -0.448, p < 0.01). Pleural thickness and the craniocaudal and horizontal extension of pleural thickening, as determined by chest computed tomography (CT), were also negatively correlated with %VC (r = -0.226, p < 0.05; r = -0.409, p < 0.01, and r = -0.408, p < 0.01, respectively).

Conclusions: DPT develops after a long latency period following occupational asbestos exposure and causes marked respiratory dysfunction. The extension of DPT should be evaluated by chest CT, and chest X-ray would be important for the evaluation of the involvement of the CPA.

In plain English

This was a retrospective review of the medical records of 106 patients (103 men, 3 women) diagnosed with asbestos-related diffuse pleural thickening (DPT) at several institutions in Japan. All had occupational asbestos exposure, most often in asbestos product manufacturing, shipbuilding, construction or heat insulation work. The article did not identify the asbestos fiber types these patients were exposed to. Exposure lasted a median of 25 years, and the median time from first exposure to DPT was 47 years. Half the patients had a history of benign asbestos pleural effusion. Percent vital capacity (%VC), the lung measure the authors used, was below 80 in 96 patients (91.0%). Greater involvement of the costophrenic angle on chest X-ray was linked to lower %VC (r = -0.448). So were pleural thickness and the vertical and horizontal spread of thickening on CT (r = -0.226, -0.409 and -0.408). Two reading groups agreed poorly on the extent of thickening on X-ray. The authors concluded that DPT develops after a long latency following occupational exposure, and they suggested evaluating its extent with CT. They noted that they could not identify the full exposed group the patients came from.

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 review of medical records of patients diagnosed with DPT at the researchers' institutions (multi-institution case series)
• Who was studied: 106 patients (103 men, 3 women) diagnosed with asbestos-related DPT at the participating institutions in Japan between August 1993 and November 2011; median age 70 years (range 46 to 88)
• Exposure: Occupational asbestos exposure, mainly asbestos product manufacturing (17), shipbuilding (14), construction (13), heat insulation work (12), and plumbing, asbestos spraying and electrical work (7 each). Median exposure duration 25 years (range 2 to 54). No patient had suspected neighborhood exposure. The fiber types these patients were exposed to were not identified.
• Main results:
  • In the 106 patients, the median latency from first asbestos exposure to onset of DPT was 47 years (range 25 to 66)
  • 53 patients (50.0%) had a medical history of benign asbestos pleural effusion (BAPE)
  • Pleural plaques were seen in 97 patients (91.5%). Asbestosis (ILO profusion above 1) was present in 7 patients (6.6%).
  • Median percent vital capacity (%VC) was 54.3% (range 17.3 to 99.4). Restrictive impairment (described as 'constrictive', %VC below 80) was found in 96 patients (91.0%), obstructive impairment (FEV1/FVC below 70) in 29 patients (28%), and mixed impairment in 25 patients (24.0%).
  • On chest X-ray, the craniocaudal (vertical) extension of pleural thickening was negatively correlated with %VC (r = -0.483, p less than 0.01). Involvement of the costophrenic angle was also negatively correlated with %VC (r = -0.448, p less than 0.01).
  • On chest CT, pleural thickness (r = -0.226, p less than 0.05), craniocaudal extension (r = -0.409, p less than 0.01) and horizontal extension (r = -0.408, p less than 0.01) of pleural thickening were negatively correlated with %VC
  • Among the 52 patients with a costophrenic angle score of 2, %VC tended to be lower with bilateral than with unilateral involvement. The difference was not statistically significant (p = 0.078).
  • Agreement between the two reading groups (Cohen's kappa) was 0.206 for X-ray craniocaudal extension, 0.431 for costophrenic angle involvement, 0.441 for CT pleural thickness, 0.843 for CT craniocaudal extension and 0.565 for CT horizontal extension. The authors interpreted this to mean that X-ray evaluation of DPT extent is subjective and less reliable.
• The authors' conclusion: The authors concluded that DPT develops after a long latency following occupational asbestos exposure and causes marked respiratory dysfunction. They suggested that DPT extent be evaluated by chest CT. They also suggested that the mMRC dyspnea scale, costophrenic angle involvement on chest X-ray, and the extent of thickening on CT may be useful for evaluating the disease.
• Limitations the authors state:
  • As a retrospective study, it could not determine the initial cohort, such as all subjects with asbestos exposure
  • The mMRC dyspnea scale used to assess breathlessness is subjective

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: Diffuse Pleural Thickening, Asbestos Exposure, Dyspnea, Latency, Costophrenic angle, Pleural Thickness, Pleural Thickening, Chest X-Ray.

Related studies

• A retrospective study on radiological findings of diffuse pleural thickening with benign asbestos pleural effusion in Japanese cases — T. Kishimoto, K. Kato, et al. (2022)
• Asbestos-related pleural diseases: dimensional criteria are not appropriate to differentiate diffuse pleural thickening from pleural plaques — J. Ameille, M. Matrat, et al. (2004)
• 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)
• Diffuse thickening superimposed on circumscribed pleural thickening related to asbestos exposure — A. Miller, J.A. Miller (1993)
• Diffuse pleural thickening following heart failure-related pleural effusions in an asbestos exposed patient — M. Evison, P. Barber (2015)
• Benign asbestos-related pleural disease — C. King, D. Mayes, et al. (2011)

Browse more research in Respiration; International Review of Thoracic Diseases, or return to medical research.