Radiographic readings for asbestosis: misuse of science--validation of the ILO classification

Our plain-English summary of Radiographic readings for asbestosis: misuse of science--validation of the ILO classification, by A. Miller (American Journal of Industrial Medicine, 2007).

The study

• Author: A. Miller
• Journal: American Journal of Industrial Medicine
• Published: 2007;50(1):63-7
• Type of article: Review
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Background: Radiographic readings for pneumoconiosis (both asbestosis and silicosis), even those using the International Labour Office (ILO) Classification, have received widespread negative coverage in the media and strong judicial rebuke.

Methods: The medical literature over the past 90 years was reviewed for the relationships between radiographic severity (standardized as the ILO profusion score) and indices of exposure to silica or asbestos, tissue burden of silica particles or asbestos fibers, histologic fibrosis, various measurements of pulmonary function and mortality.

Results: Evidence from many different disciplines has demonstrated that the ILO profusion score correlates with occupational exposure, dust burden in the lung, histologic fibrosis and, more recently, with physiologic impairment and mortality.

Conclusions: The ILO Classification has therefore been validated as a scientific tool. Its fraudulent misuse by "hired-gun" physicians, attorneys and elements of the compensation system to falsify claims of asbestosis and/or silicosis (often in the same claimant) must be condemned.

(c) 2006 Wiley-Liss, Inc.

In plain English

This article, labelled a 'Historical Perspective', reviewed 90 years of medical literature on whether the ILO Classification, the standard system for grading chest X-rays for pneumoconiosis, reflects real disease. It reported no new data. Its findings came from earlier studies, several by the author. In a 1992 study of 2,611 insulators, lung capacity (FVC) generally fell as the X-ray profusion score rose. It did not differ between scores 0/1 and 1/0. It was lower in workers with pleural thickening and in smokers. In a study of 5,011 asbestos-exposed workers, diffusing capacity fell progressively with increasing profusion. In a 10-year follow-up of insulators, the risk of death from asbestosis rose from 0.9% at baseline ILO category 0 to 35.4% at category 3. The author concluded that a properly read ILO chest film is a valid scientific instrument. The author added that a negative reading does not rule out disease when lung function is impaired in a manner consistent with asbestos-related disease, and that a 1/0 reading alone does not establish disease. The author also condemned fraudulent misuse of readings in compensation claims.

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: Narrative review (published as a 'Historical Perspective') that summarized earlier studies, several by the author. It presented no new data.
• Who was studied: No new subjects. The reviewed studies included 2,611 North American insulators, 1,245 sheet metal workers, 5,011 workers from a variety of trades, and a 10-year mortality follow-up of insulators.
• Exposure: Occupational asbestos exposure among insulators, sheet metal workers, and workers in refineries, chemical plants and construction. The broader review also covered silica. No fiber types were named.
• Main results:
  • In the earlier study of 2,611 insulators (Miller et al., 1992), FVC was abnormal (mean 89.8% of predicted) even when the X-ray score was normal (0/0) and pleural thickening was absent.
  • In the same insulators, FVC decreased as profusion score increased, except that there was no difference between scores 0/1 and 1/0.
  • In the same insulators, FVC was lower at any score in workers with pleural thickening and in smokers.
  • In 1,245 sheet metal workers (Miller et al., 1996), FVC also fell with increasing score. The decline was less steep than in the insulators, consistent with their lesser exposure.
  • In 5,011 asbestos-exposed workers (Miller et al., 2004), diffusing capacity decreased progressively with increasing profusion.
  • In a 10-year follow-up of insulators (Markowitz et al., 1997), the risk of death from asbestosis by baseline ILO category was 0.9% for category 0, 2.4% for category 1, 10.8% for category 2 and 35.4% for category 3.
  • In an earlier study (Lilis et al., 1991), an overall index of pleural thickening was significantly inversely related to FVC for circumscribed pleural thickening (plaques), but not for diffuse pleural thickening.
• The authors' conclusion: The author concluded that a chest film properly read using the ILO Classification is a valid scientific instrument reflecting the severity of asbestos-caused pleuropulmonary disease. The author added that a 1/0 reading by itself does not establish disease, and a 0/1 or 0/0 reading does not rule it out.
• Limitations the authors state:
  • The author noted that the plain chest film is somewhat insensitive. A negative reading does not rule out disease when pulmonary function is impaired in a manner consistent with asbestos-related disease.
  • The author noted that the ILO Classification was intended for epidemiologic purposes rather than for diagnosing individual cases.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: ILO Classification, Pneumoconiosis, Silicosis, Fibrosis, Occupational Exposure.

Related studies

• TruCutR needle biopsy in asbestosis and silicosis: correlation of histological changes with radiographic changes and pulmonary function in 41 patients — P. Tukiainen, E. Taskinen, et al. (1978)
• MetLife and its corporate allies: dust diseases and the manipulation of science — D.S. Egilman, T. Bird, et al. (2013)
• Follow-up of asbestosis patients and predictors for radiographic progression — P. Oksa, M.S. Huuskonen, et al. (1998)
• Asbestosis and silicosis — G.R. Wagner (1997)
• Silico-asbestosis that responded to steroid therapy — S. Hoshi, Y. Tamai, et al. (2006)
• Asymmetric rapidly progressive lung fibrosis: a cause of pseudotumour in asbestosis — W.O. Cookson, J.J. Glancy, et al. (1985)

Browse more research in American Journal of Industrial Medicine, or return to medical research.