Asbestos bodies in bronchoalveolar lavage in the 21st century: a time-trend analysis in a clinical population

Our plain-English summary of Asbestos bodies in bronchoalveolar lavage in the 21st century: a time-trend analysis in a clinical population, by V. Nuyts, H. Vanhooren, S. Begyn, et al (Occupational and Environmental Medicine, 2017).

The study

• Authors: V. Nuyts, H. Vanhooren, S. Begyn, K. Nackaerts, B. Nemery
• Journal: Occupational and Environmental Medicine
• Published: 2017;74(1):59-65
• Cited by: 9 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objectives: Asbestos bodies (AB) in bronchoalveolar lavage (BAL) can be detected by light microscopy and their concentration is indicative of past cumulative asbestos exposure. We assessed clinical and exposure characteristics, as well as possible time trends, among patients in whom AB had been quantified in BAL.

Methods: BAL samples obtained from 578 participants between January 1997 and December 2014 were available for analysis. The processing of samples and the microscopic analysis were performed by a single expert and 76% of samples came from a single tertiary care hospital, allowing clinical and exposure data to be extracted from patient files.

Results: The study population (95% males) had a mean age of 62.5 (±12.4) years. AB were detected in 55.2% of the samples, giving a median concentration of 0.5 AB/mL (95th centile: 23.6 AB/mL; highest value: 164.5 AB/mL). The AB concentration exceeded 1 AB/mL in 39.4% and 5 AB/mL in 17.8%. A significant decrease from a geometric mean of 0.93 AB/mL in 1997 to 0.2 AB/mL in 2014 was apparent. High AB concentrations generally corresponded with occupations with (presumed) high asbestos exposure. AB concentrations were higher among patients with asbestosis and pleural plaques, when compared with other disease groups. Nevertheless, a substantial proportion of participants with likely exposure to asbestos did not exhibit high AB counts.

Conclusions: This retrospective study of a large clinical population supports the value of counting AB in BAL as a complementary approach to assess past exposure to asbestos.

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In plain English

This retrospective study counted asbestos bodies, which are asbestos fibres coated with iron-rich proteins, under a light microscope in lung-wash fluid (bronchoalveolar lavage). The samples came from 578 patients tested at a laboratory at University Hospital Leuven, Belgium, between 1997 and 2014. Asbestos bodies were found in 55.2% of samples. In 39.4% there was more than 1 per mL, and in 17.8% more than 5 per mL. The geometric mean fell from 0.93 per mL in 1997 to 0.20 per mL in 2014. Levels were generally higher in jobs with presumed high exposure and in patients with asbestosis or pleural plaques, but values varied widely. Almost half of patients with presumed high exposure had no asbestos bodies (29%) or between 0.1 and 1 per mL (18%). Six of 44 patients with asbestosis had none. The authors concluded that counting asbestos bodies can help document past exposure, but that finding none should not be used to conclude a person had no substantial exposure. They noted that the data came from clinical records not collected for research.

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 study of asbestos body counts in bronchoalveolar lavage samples, linked to clinical and occupational information from patient files
• Who was studied: 588 bronchoalveolar lavage samples from 578 patients whose asbestos bodies were counted at the Laboratory of Pneumology, University Hospital Leuven (UZ Leuven), Belgium, between 1 January 1997 and 31 December 2014. 140 samples (24%) came from other hospitals. 95.3% were male, and the mean age was 62.5 years.
• Exposure: Past asbestos exposure, measured as asbestos bodies (asbestos fibres, generally amphibole, surrounded by iron-rich proteins) counted by light microscopy in lavage fluid. Patients were also placed in five groups by presumed occupational exposure: definite contact with raw asbestos (e.g. shipyard and insulation workers), likely contact (e.g. joiners, welders, heating mechanics), occasional exposure, presumably no occupational exposure, and unknown exposure.
• Main results:
  • Of 578 participants, 319 (55.2%) had at least one asbestos body. Concentrations exceeded 1 AB/mL in 228 (39.4%) and 5 AB/mL in 103 (17.8%). The median was 0.5 AB/mL and the highest value 164.5 AB/mL.
  • Concentrations decreased over the study period. The geometric mean was 0.93 AB/mL in 1997 and 0.20 AB/mL in 2014. The Spearman correlation with bronchoscopy date was r = −0.19 (95% CI −0.27 to −0.11; p less than 0.0001).
  • Concentrations differed across the five occupational groups, falling from the highest to the lowest presumed exposure categories (p less than 0.0001). However, almost half of participants with presumed high exposure had no asbestos bodies (29%) or between 0.1 and 1 AB/mL (18%). Almost a quarter of those without suspected occupational exposure had more than 1 AB/mL.
  • The highest median and mean concentrations were in participants with asbestosis and those with pleural plaques. The lowest were in patients with other diseases and those with no clinical information.
  • Of 44 patients with asbestosis, most (73%) had more than 1 AB/mL, but 6 (13.6%) had no asbestos bodies. Among patients with interstitial lung disease not labelled as asbestosis, 30.6% had more than 1 AB/mL and 8.3% more than 5 AB/mL.
  • Of 54 patients with lung cancer, half had at least 1 AB/mL. Eight (15%) exceeded 5 AB/mL, the level the authors described as meeting the Belgian Fund for Occupational Diseases criteria for asbestos-induced lung cancer.
• The authors' conclusion: The authors concluded that asbestos body concentrations in lavage fluid decreased progressively in the 21st century in this Belgian patient population. They concluded that counting asbestos bodies remains helpful to document or discover past exposure, but that their absence should not be used to conclude that a person did not have substantial exposure if other evidence suggests otherwise.
• Limitations the authors state:
  • The study relied on clinical data collected without research purposes. Occupational information, such as duration of exposure, was often missing.
  • Whether a lavage was done and an asbestos body count requested depended on the disease and on the treating physician. The authors could not control for this.
  • The large proportion of zero values complicated the statistical analyses.
  • The authors could not always tell whether diagnoses were made before or after the asbestos body counts were known.
  • The study could not verify whether the decline in asbestos bodies was accompanied by fewer or less severe asbestos-related diseases.
  • The authors could not entirely exclude explanations for the decline other than decreased asbestos use, such as changes in clinical practice or referral patterns.

Topics

Medical terms in this study, explained in our Lexicon: Asbestos Bodies, Bronchoalveolar Lavage (BAL), Asbestos Exposure, Pleural Plaques.

Related studies

• Asbestos bodies in bronchoalveolar lavage fluids of brake lining and asbestos cement workers — P. Dumortier, P. De Vuyst, et al. (1990)
• Diagnostic value of asbestos bodies in bronchoalveolar lavage fluid — P. De Vuyst, P. Dumortier, et al. (1987)
• Asbestos bodies in bronchoalveolar lavage in relation to asbestos bodies and asbestos fibres in lung parenchyma — A. Karjalainen, R. Piipari, et al. (1996)
• Asbestos bodies in bronchoalveolar lavage fluid in relation to occupational history — A. Karjalainen, S. Anttila, et al. (1994)
• Erionite bodies and fibres in bronchoalveolar lavage fluid (BALF) of residents from Tuzköy, Cappadocia, Turkey — P. Dumortier, L. Coplü, et al. (2001)
• Distribution of asbestos bodies in the human lung as determined by bronchoalveolar lavage — H. Teschler, N. Konietzko, et al. (1993)

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