Interstitial Lung Abnormalities Detected by CT in Asbestos-Exposed Subjects Are More Likely Associated to Age

Our plain-English summary of Interstitial Lung Abnormalities Detected by CT in Asbestos-Exposed Subjects Are More Likely Associated to Age, by F. Laurent, I. Benlala, G. Dournes, et al (Journal of Clinical Medicine, 2021).

The study

• Authors: F. Laurent, I. Benlala, G. Dournes, C. Gramond, I. Thaon, B. Clin, P. Brochard, A. Gislard, P. Andujar, S. Chammings, J. Gallet, A. Lacourt, F. Delva, C. Paris, G. Ferretti, J.C. Pairon
• Journal: Journal of Clinical Medicine
• Published: 2021;10(14)
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: the aim of this study was to evaluate the association between interstitial lung abnormalities, asbestos exposure and age in a population of retired workers previously occupationally exposed to asbestos.

Methods: previously occupationally exposed former workers to asbestos eligible for a survey conducted between 2003 and 2005 in four regions of France, underwent chest CT examinations and pulmonary function testing. Industrial hygienists evaluated asbestos exposure and calculated for each subject a cumulative exposure index (CEI) to asbestos. Smoking status information was also collected in this second round of screening. Expert radiologists performed blinded independent double reading of chest CT-scans and classified interstitial lung abnormalities into: no abnormality, minor interstitial findings, interstitial findings inconsistent with UIP, possible or definite UIP. In addition, emphysema was assessed visually (none, minor: emphysema <25%, moderate: between 25 and 50% and severe: >50% of the lung). Logistic regression models adjusted for age and smoking were used to assess the relationship between interstitial lung abnormalities and occupational asbestos exposure.

Results: the study population consisted of 2157 male subjects. Interstitial lung abnormalities were present in 365 (16.7%) and emphysema in 444 (20.4%). Significant positive association was found between definite or possible UIP pattern and age (OR adjusted =1.08 (95% CI: 1.02-1.13)). No association was found between interstitial abnormalities and CEI or the level of asbestos exposure.

Conclusion: presence of interstitial abnormalities at HRCT was associated to aging but not to cumulative exposure index in this cohort of former workers previously occupationally exposed to asbestos.

In plain English

This French study analysed chest CT scans from the second round of a screening program for retired asbestos-exposed workers. It included 2157 men. Industrial hygienists scored each man's asbestos exposure from his work history as a cumulative exposure index. No air measurements were available, and the article does not name fiber types. Expert radiologists read the scans without knowing exposure levels. The authors reported interstitial lung abnormalities in 365 men (16.7%). A possible or definite usual interstitial pneumonia (UIP) pattern was associated with age, with an adjusted odds ratio of 1.08 for each additional year (95% CI 1.02–1.13). No significant association was found between interstitial abnormalities and the cumulative exposure index or the maximum exposure level. Ex-smokers had higher odds of UIP patterns, statistically significant before adjustment but not after. Emphysema was associated with a high maximum exposure level (adjusted odds ratio 2.27, 95% CI 1.08–4.80) but not with the cumulative index. The authors suggested the men with interstitial abnormalities may have early interstitial lung disease rather than asbestosis. They noted possible selection bias, no control group and no tissue confirmation.

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: Analysis of CT scans and questionnaire data from the second round of a voluntary screening program (Asbestos Post-Exposure Survey, APEXS) for former asbestos-exposed workers, using logistic regression adjusted for age and smoking
• Who was studied: 2157 male retired workers previously occupationally exposed to asbestos, without already compensated asbestos-related disease, from four regions of France. The first screening round ran from October 2003 to December 2005 and the second round about 5 years later. 92 women and 19 men with missing smoking data were excluded.
• Exposure: Occupational asbestos exposure estimated by industrial hygienists from each subject's full work history. Exposure was expressed as a cumulative exposure index (duration multiplied by intensity weighting factors of 0.01, 0.1, 1 or 10) in exposure units x years, as maximum exposure level, as duration and as time since first exposure. Fiber types were not reported and no air measurements were made.
• Main results:
  • Interstitial lung abnormalities were reported in 365 of the 2157 men (16.7%).
  • Possible or definite UIP pattern was positively associated with age at CT, for each additional year: crude odds ratio 1.08 (95% CI 1.03–1.13), adjusted odds ratio 1.08 (95% CI 1.02–1.13).
  • No significant association was found between interstitial abnormalities and the cumulative exposure index or the maximum level of asbestos exposure.
  • Ex-smokers had higher crude odds of possible or definite UIP pattern than non-smokers (odds ratio 2.13, 95% CI 1.03–4.39). After adjustment the odds ratios remained above 1 (2.03, 95% CI 0.98–4.21; and 1.92, 95% CI 0.92–4.00) but were no longer statistically significant.
  • When UIP or possible UIP was grouped with interstitial patterns inconsistent with UIP, the association with age remained significant: crude odds ratio 1.09 (95% CI 1.06–1.12), adjusted odds ratio 1.09 (1.05–1.13). The association with asbestos exposure remained non-significant.
  • Emphysema was not associated with the cumulative exposure index. It was associated with a high maximum level of asbestos exposure: crude odds ratio 2.05 (95% CI 1.06–3.99), adjusted odds ratio 2.27 (95% CI 1.08–4.80).
• The authors' conclusion: The authors concluded that interstitial abnormalities on HRCT in this population were associated with aging, not with the level of asbestos exposure. They suggested that subjects with these interstitial abnormalities may have a preclinical interstitial lung disease rather than asbestosis, and raised the question of these abnormalities as an early stage of idiopathic pulmonary fibrosis.
• Limitations the authors state:
  • Excluding subjects already compensated before the first round may have introduced selection bias.
  • Participation was voluntary, and reasons for not taking part in the second round were unknown.
  • No atmospheric measurements were made and frequency of exposure was often unknown, so exposure was expressed in exposure units x years rather than fibers/mL x years.
  • A substantial fraction of subjects with overt asbestosis were likely not included.
  • There was no histological (tissue) proof of asbestosis.
  • There was no control group of non-exposed subjects.
  • The lack of association with time-related exposure measures (duration, time since first exposure) could reflect over-adjustment for age.
  • The analysis predates the current international consensus guideline for diagnosing idiopathic pulmonary fibrosis.

Topics

Medical terms in this study, explained in our Lexicon: Interstitial, Asbestos Exposure, Cumulative Exposure, Emphysema, High-Resolution CT (HRCT).

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• Relationships between asbestos exposure and pleural plaques: dose and time effects using fractional polynomials — M. Menant, I. Benlala, et al. (2024)
• Occupational exposure to ultrafine particles and lung cancer in a population exposed to asbestos — C. Rostello, C. Gramond, et al. (2025)

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