Chest radiographs in subjects with asbestos-related abnormalities: comparison between ILO categorizations and clinical reading

Our plain-English summary of Chest radiographs in subjects with asbestos-related abnormalities: comparison between ILO categorizations and clinical reading, by B. Hilt, A. Borgerson, J.T. Lien, et al (American Journal of Industrial Medicine, 1992).

The study

• Authors: B. Hilt, A. Borgerson, J.T. Lien, S. Langård
• Journal: American Journal of Industrial Medicine
• Published: 1992;21(6):855-61
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004866).

Abstract

The findings of a previous chest X-ray screening, determined without using standardized criteria, were reassessed by means of the ILO classification. Of 470 radiographs that had been determined as showing asbestos-related changes, 430 were categorized according to the ILO Classification. Small opacities with profusion greater than or equal to 1/0 were described in 39 (52%) of 75 participants who, on the original clinical reading, had been determined as having lung fibrosis, and in 45 (12.7%) of 355 who were determined as having pleural changes only. When considering circumscribed pleural thickening at the chest wall or diaphragm, as categorized by the ILO Classification, such changes were present in 401 (93.7%) of 428 subjects with pleural changes as determined on the clinical reading. In addition to the improved sensitivity and specificity achieved, the ILO Classification also allows comparison with other studies. The most apparent disadvantage of the ILO system is that it cannot firmly separate the various types of asbestos-related pleural changes. The study revealed that the previous asbestos exposure of the case subjects had occurred in many different workplaces and occupations.

In plain English

This study re-read chest X-rays from an earlier screening of 21,483 men aged 40 and over in Telemark County, Norway, carried out from 1982 to 1984. In that screening, doctors had judged 470 men to have asbestos-related changes without using standardized criteria. Two experienced radiologists jointly re-read 430 of these X-rays using the ILO Classification, a standard scoring system. Of 75 men originally judged to have lung fibrosis, 39 (52%) had small lung opacities at profusion 1/0 or more under the ILO system. So did 45 (12.7%) of 355 men originally judged to have pleural changes only. Circumscribed pleural thickening was found in 401 (93.7%) of 428 men originally said to have pleural changes. The men's asbestos exposure had occurred in many different workplaces and trades. The authors concluded that, if the ILO reading by the two readers was accepted as the standard, the original clinical reading was rather poor at detecting asbestos-related lung fibrosis. They noted that the re-readers knew abnormalities had already been seen, and that normal X-rays could not be mixed in.

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: Re-reading of chest radiographs from an earlier population screening. Radiographs first read clinically without strict criteria were re-classified by two readers reaching consensus with the ILO Classification, and the two readings were compared.
• Who was studied: 21,483 men aged 40 and over in Telemark County, Norway, screened with 100 mm chest X-rays from 1982 to 1984. 1,431 were called for clinical examination and 1,372 attended. Of these, 470 were judged to have asbestos-related changes: 86 with lung fibrosis alone or with pleural plaques, and 384 with pleural plaques only. 40 had been reported to the Directorate of Labour Inspection before 1980, so 430 radiographs were categorized.
• Exposure: Past asbestos exposure reported in work-history interviews; fiber types not stated. Workplaces included electrochemical industries (maintenance and production), ferroalloy industries, shipyards, building industries, electrical equipment industries, work as a seaman, and others. Men with ILO profusion 1/0 or more: mean time since first exposure 43.5 (9-67) years, mean duration of exposure 4.4 (1-24) years. Men with pleural changes only: 42.1 (10-69) and 3.4 (1-30) years.
• Main results:
  • Among 75 men judged at clinical examination to have radiological lung fibrosis, 39 (52%) had irregular opacities of profusion 1/0 or more on ILO categorization.
  • Among 355 men judged at clinical examination to have pleural changes only, 45 (12.7%) also had lung fibrosis (profusion 1/0 or more) on ILO categorization.
  • Circumscribed pleural thickening at the chest wall or diaphragm was categorized by ILO in 401 (93.7%) of 428 men originally characterized as having pleural changes.
  • On ILO categorization, 164 (37.7%, as printed) had diffuse pleural thickening and 264 (60.7%) had pleural calcification. Individuals could have more than one type.
  • All but one of the 430 men reassessed had radiographic abnormalities on ILO categorization.
  • Taking the ILO reading as the standard, the authors reported that the specificity of the clinical reading was 57.3% for lung fibrosis and 93.9% for pleural plaques.
  • Previous asbestos exposure had taken place in a variety of workplaces and trades.
• The authors' conclusion: The authors concluded that, if the ILO categorization by two experienced readers is accepted as a standard, the clinical reading was rather poor at detecting asbestos-related lung fibrosis. They also suggested that population rates of asbestos-related radiographic changes are more likely underestimated than overestimated.
• Limitations the authors state:
  • Comparing the two reading procedures was difficult because the methods differed.
  • For practical reasons, normal X-rays could not be mixed into the ILO reading.
  • The ILO readers knew that some abnormality had already been seen on the radiographs.
  • The comparison was limited by expected variation within and between readers.
  • The ILO Classification cannot firmly distinguish extrapleural fat from diffuse pleural thickening, nor large plaques from diffuse thickening.

Topics

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

Medical terms in this study, explained in our Lexicon: Chest X-Ray, ILO Classification, Fibrosis, Pleural Thickening, Diaphragm, Asbestos Exposure.

Related studies

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• Risk and significance of chest radiograph and pulmonary function abnormalities in an elderly cohort of former nuclear weapons workers — M.A. Mikulski, P.G. Hartley, et al. (2011)
• Comparison of "B" readers' interpretations of chest radiographs for asbestos related changes — J.N. Gitlin, L.L. Cook, et al. (2004)
• Comparison of B readers' interpretations of chest radiographs for asbestos related changes — K.D. Rosenman (2004)
• Comparison of B readers' interpretations of chest radiographs for asbestos related changes — J.P. Kassirer (2004)

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