A preliminary study of observer variation in the classification of radiographs of asbestos-exposed workers and the relation of pathology and x-ray appearances

Our plain-English summary of A preliminary study of observer variation in the classification of radiographs of asbestos-exposed workers and the relation of pathology and x-ray appearances, by A. Caplan, I. C. Gilson, J. C. McVittie, et al (1965).

The study

• Authors: A. Caplan, I. C. Gilson, J. C. McVittie, K. F. W. Hinson, L. C. Wagner
• Published: Annals of the New York Academy of Sciences, pp. 179-180 (Conference on the Biological Effects of Asbestos) (1965)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library. The article is still under copyright, so we describe it here rather than post it.

In plain English

This preliminary study examined how consistently doctors classified chest X-rays of asbestos-exposed workers with an extended 1958 ILO classification, and how X-ray findings matched autopsy findings. The material was 50 X-rays of asbestosis cases from the South African Pneumoconiosis Bureau in Johannesburg, 64 from the London Pneumoconiosis Panel, and autopsy reports on London cases. Readers in the two countries classified the films separately and then together. South African readers recorded linear markings more often. Repeat readings by the same observer agreed fairly well, but single observers could depart appreciably from the final agreed reading. In one set of 20 films, one observer reported pleural thickening in all 20. Pleural thickening was reported rather more often on X-ray than at autopsy. Of the cases with linear markings on X-ray, 37 (82 per cent) showed asbestosis visible to the naked eye at autopsy, and eight did not. Only three of seven cases of pleural calcification seen on X-ray were confirmed. The authors noted incomplete pathology records. They concluded that the system promised to be useful and warranted a larger study.

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: Preliminary study of agreement between and within X-ray readers using an extended ILO classification, with comparison of the agreed X-ray readings against autopsy findings
• Who was studied: Chest X-rays of men with asbestosis who had recently applied for compensation: 50 diagnosed at the South African Pneumoconiosis Bureau in Johannesburg and 64 diagnosed at the London Pneumoconiosis Panel of the Ministry of Pensions and National Insurance, plus autopsy reports on London-area cases. Women were excluded, as were cases complicated by tuberculosis, mixed pneumoconiosis or other lung fibrosis. Lung cancer cases in the UK series were not excluded. The scanned text prints the number of autopsy cases inconsistently.
• Exposure: Asbestos exposure in workers diagnosed with asbestosis and applying for compensation. The article does not specify fiber types or jobs for the cases studied.
• Main results:
  • The South African readers recorded linear markings more frequently than the United Kingdom readers.
  • The readers agreed that 20 per cent of the films showed small opacities (simple pneumoconiosis).
  • When the same observers reread the films, agreement with their own earlier readings was fairly high. However, a single observer's readings could deviate appreciably from the final agreed reading. In one group of 20 films, observer three reported pleural thickening present in all 20.
  • In the UK cases, pleural thickening was reported rather more often on X-ray than at autopsy. There were also seven cases in which it was found at autopsy but not reported on the X-ray.
  • Of seven cases with pleural calcification detected on X-ray, only three were confirmed at autopsy.
  • Of the cases with linear markings on the X-ray, 37 (82 per cent) showed asbestosis visible to the naked eye at autopsy. The scan prints the total as '15'. Adding the 37 to the eight cases without such evidence gives 45, and 37 is 82 per cent of 45.
  • Eight cases showed linear markings on the X-ray but no asbestosis visible to the naked eye at autopsy.
• The authors' conclusion: The authors concluded that a system built on the 1958 ILO Classification promises to be useful for classifying asbestosis. They considered the results encouraging enough to warrant a larger study with a wider range of films from different countries and occupational groups.
• Limitations the authors state:
  • The pathology records were incomplete and had not been made with this investigation in view. The authors said this may partly explain why calcification seen on X-ray was rarely confirmed.
  • The parietal pleura was not always examined at autopsy.
  • In about half the cases a tumor was present at autopsy. This often made it difficult to tell fibrosis due to asbestos apart from fibrosis due to collapse and infection.
  • Some cases had also been exposed to other toxic dusts, which made interpretation difficult.
  • Lung cancer was so common in the United Kingdom series that excluding these cases was impracticable.

Topics

Medical terms in this study, explained in our Lexicon: Pathology, Chest X-Ray, ILO Classification, Autopsy, Pneumoconiosis, Pleural Thickening, Pleural Calcification.

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