Asbestos-related pleural and lung fibrosis in patients with retroperitoneal fibrosis

Our plain-English summary of Asbestos-related pleural and lung fibrosis in patients with retroperitoneal fibrosis, by T. Uibu, R. Järvenpää, J. Hakomäki, et al (Orphanet Journal of Rare Diseases, 2008).

The study

• Authors: T. Uibu, R. Järvenpää, J. Hakomäki, A. Auvinen, E. Honkanen, K. Metsärinne, P. Roto, H. Saha, J. Uitti, P. Oksa
• Journal: Orphanet Journal of Rare Diseases
• Published: 2008;3:29
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Background: Retroperitoneal fibrosis (RPF) is a rare fibroinflammatory disease that leads to hydronephrosis and renal failure. In a case-control study, we have recently shown that asbestos exposure was the most important risk factor for RPF in the Finnish population. The aim of this study was to evaluate the relation of asbestos exposure to radiologically confirmed lung and pleural fibrosis among patients with RPF.

Methods: Chest high-resolution computed tomography (HRCT) was performed on 16 unexposed and 22 asbestos-exposed RPF patients and 18 asbestos-exposed controls. Parietal pleural plaques (PPP), diffuse pleural thickening (DPT) and parenchymal fibrosis were scored separately.

Results: Most of the asbestos-exposed RPF patients and half of the asbestos-exposed controls had bilateral PPP, but only a few had lung fibrosis. Minor bilateral plaques were detected in two of the unexposed RPF patients, and none had lung fibrosis. DPT was most frequent and thickest in the asbestos-exposed RPF-patients. In three asbestos-exposed patients with RPF we observed exceptionally large pleural masses that were located anteriorly in the pleural space and continued into the anterior mediastinum.Asbestos exposure was associated with DPT in comparisons between RPF patients and controls (case-control analysis) as well as among RPF patients (case-case analysis).

Conclusion: The most distinctive feature of the asbestos-exposed RPF patients was a thick DPT. An asbestos-related pleural finding was common in the asbestos-exposed RPF patients, but only a few of these patients had parenchymal lung fibrosis. RPF without asbestos exposure was not associated with pleural or lung fibrosis. The findings suggest a shared etiology for RPF and pleural fibrosis and furthermore possibly a similar pathogenetic mechanisms.

In plain English

This Finnish study used chest CT scans to look for asbestos-related scarring of the lungs and pleura (lung lining) in people with retroperitoneal fibrosis (RPF), a rare scarring disease around the abdominal aorta. Participants from the authors' earlier case-control study were 16 unexposed and 22 asbestos-exposed RPF patients and 18 controls without RPF with at least 10 fiber-years of exposure. Bilateral pleural plaques appeared in over 60% of exposed RPF patients and half of exposed controls. Among RPF patients, bilateral plaques were seen in 14 of 22 exposed versus 2 of 16 unexposed patients (odds ratio 12.2, 95% confidence interval 2.2 to 68.2). Diffuse pleural thickening was more common in exposed than unexposed RPF patients. Among those who had it, mean maximum thickness was 9.8 mm in 12 exposed RPF patients and 5.1 mm in 7 exposed controls. Lung fibrosis was uncommon in every group. The authors concluded the findings suggest a shared cause for RPF and pleural fibrosis. They noted this study alone cannot show that asbestos causes RPF, and that numbers were small.

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: Imaging (chest high-resolution CT) study nested within the authors' earlier case-control study of RPF. It included case-control comparisons (exposed RPF patients vs exposed controls) and case-case comparisons (exposed vs unexposed RPF patients).
• Who was studied: 38 RPF patients (16 without and 22 with asbestos exposure) and 18 asbestos-exposed controls without RPF, in Finland. Scans were done in seven central hospitals. Participation was 88% of RPF patients and 86% of eligible controls. The article does not give the years of the study.
• Exposure: Cumulative asbestos exposure was estimated by interview with an occupational health physician who did not know who was a patient and who was a control. It was graded in fiber-years as none, slight (under 10 fiber-years) or moderate-to-high (10 or more fiber-years). All controls had 10 or more fiber-years. The article does not specify the fiber types the participants were exposed to.
• Main results:
  • Bilateral pleural plaques were found in more than 60% of asbestos-exposed RPF patients and in half of the asbestos-exposed controls.
  • Unexposed RPF patients had only minor pleural plaques (class 2 or lower).
  • Case-case comparison among RPF patients: bilateral parietal pleural plaques in 14 of 22 exposed vs 2 of 16 unexposed patients, odds ratio 12.2 (95% CI 2.2 to 68.2).
  • Case-case comparison among RPF patients: any pleural fibrosis (bilateral plaques and/or diffuse pleural thickening) in 17 of 22 exposed vs 6 of 16 unexposed patients, odds ratio 5.7 (95% CI 1.4 to 23.4).
  • Diffuse pleural thickening was more frequent in exposed than unexposed RPF patients (P = 0.045). In Table 3 the case-case odds ratio was 3.6 (95% CI 0.9 to 14.7), with 12 of 22 exposed vs 4 of 16 unexposed patients affected.
  • The frequency of diffuse pleural thickening did not differ between asbestos-exposed RPF patients and asbestos-exposed controls (P = 0.190).
  • Among participants who had diffuse pleural thickening, the mean of each person's maximum thickness was 2.8 mm (SD 1.0) in 4 unexposed RPF patients, 9.8 mm (SD 5.1) in 12 exposed RPF patients and 5.1 mm (SD 2.7) in 7 exposed controls. The difference across the three groups was significant (P = 0.040).
  • Compared with exposed controls, exposed RPF patients had a non-significantly increased risk of diffuse pleural thickening (OR 3.06, 95% CI 0.81 to 11.56).
  • Three asbestos-exposed RPF patients had exceptionally large pleural masses extending into the anterior mediastinum.
  • Lung fibrosis was uncommon. One exposed RPF patient had mild lung fibrosis and two had moderate changes, as did two controls. There was no notable lung fibrosis in unexposed RPF patients.
  • Exposed RPF patients were not more susceptible to lung fibrosis than exposed controls (OR 1.29, 95% CI 0.25 to 6.63).
• The authors' conclusion: The authors concluded that the findings suggest a shared cause for RPF and pleural fibrosis, and possibly similar disease mechanisms, in some subjects.
• Limitations the authors state:
  • The authors state that the findings of this study alone are not enough to declare a causal link between asbestos exposure and RPF.
  • Because numbers were small, RPF patients with slight and with moderate-to-high exposure were combined into one group.
  • The combined exposed RPF group had less exposure on average than the controls, so the regression may have underestimated the risk of pleural fibrosis linked to RPF.
  • The small number of cases did not allow interactions between asbestos and RPF to be evaluated.

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: Fibrosis, Case-Control Study, Asbestos Exposure, High-Resolution CT (HRCT), Pleural Plaques, Diffuse Pleural Thickening, Parenchymal Fibrosis, Bilateral.

Related studies

• IGG4-Related Pleural Bridging Fibrosis, Retrosternal Fibrosclerosis and Retroperitoneal Fibrosis in an Asbestos-Exposed Patient — P.P.T.E.S. Torres, L.B.M. Fonseca, et al. (2019)
• Asbestos exposure as a risk factor for retroperitoneal fibrosis — T. Uibu, P. Oksa, et al. (2004)
• Syndrome of pleural and retrosternal "bridging" fibrosis and retroperitoneal fibrosis in patients with asbestos exposure — V. Cottin, P.Y. Brillet, et al. (2008)
• Asbestos and idiopathic retroperitoneal fibrosis — J.C. Boulard, T. Hanslik, et al. (1995)
• Asbestos exposure: a potential cause of retroperitoneal fibrosis — R. Sauni, P. Oksa, et al. (1998)
• Asbestos and smoking as risk factors for idiopathic retroperitoneal fibrosis: a case-control study — M. Goldoni, S. Bonini, et al. (2014)

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