Radiological and pathological correlations in asbestosis in the Republic of South Africa and the United Kingdom. I. A proposed radiological classification of asbestosis

Our plain-English summary of Radiological and pathological correlations in asbestosis in the Republic of South Africa and the United Kingdom. I. A proposed radiological classification of asbestosis, by G.K. Sluis-Cremer, C.P. Theron (Annals of the New York Academy of Sciences, 1965).

The study

• Authors: G.K. Sluis-Cremer, C.P. Theron
• Journal: Annals of the New York Academy of Sciences
• Published: 1965;132(1):373-8
• Cited by: 11 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. 001543).

Summary of the article

The authors proposed a modification of the I.L.O. international classification of radiological opacities in pneumoconiosis for use in asbestosis. The linear opacity category was expanded into coarse (more than 1 mm wide) and fine markings, with extent graded by lung area. Calcified pleural plaques and pleural thickening were brought into the classification, with codes for their anatomical sites. Symbols were added for bronchial carcinoma, mesothelioma and cystic changes. The code was tested on four groups: 155 cases diagnosed radiologically in a population survey in the asbestos areas of the Cape and Transvaal; 120 cases certified by the Miners' Medical Bureau, Johannesburg; 50 post-mortem proven South African mining cases; and 64 post-mortem proven United Kingdom industrial cases. Single postero-anterior chest films were read by two or more readers. For the post-mortem cases, films were exchanged between the two countries, and disagreements were resolved by discussion. In the survey group, calcified plaques were seen in 82% of Cape cases (mainly crocidolite) and 76% of Transvaal cases (mainly amosite), and parenchymal changes in 40% and 84%. Certified cases showed a similar trend toward parenchymal changes in the Transvaal. In the UK cases, calcified plaques were found in 18% and parenchymal changes in 92%. The authors concluded that the code was workable, but that a standard set of films should be made available if it were widely used.

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In plain English

This paper, Part I of a series, proposed a modification of the I.L.O. classification of chest X-rays for use in asbestosis. The authors split linear opacities into coarse (more than 1 mm wide) and fine, a division they called purely arbitrary, and graded their extent by lung area. Calcified pleural plaques were placed within the classification, and pleural thickening tentatively. Symbols were added for bronchial carcinoma, mesothelioma and cystic changes. The code was tested on one hundred and fifty-five cases from a population survey in the Cape and Transvaal, 120 cases certified by the Miners' Medical Bureau, 50 post-mortem proven South African mine cases and 64 post-mortem proven United Kingdom industry cases, each read by two or more people. In the survey group, parenchymal changes were found in 40% of Cape cases (a crocidolite area) and 84% of Transvaal cases (a mainly amosite area). The certified group showed a similar trend. Calcified plaques were found in 18% of UK cases; the authors noted a greater frequency in South Africa. They concluded that the film exchange had established the code's workability.

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: Methods paper proposing a modified radiological (chest X-ray) classification for asbestosis. The authors tested it by having two or more readers read the films of four case groups, then compared how often X-ray features appeared in each group.
• Who was studied: Four groups of cases: (1) 155 cases diagnosed on X-ray as asbestosis in a population survey by the Pneumoconiosis Research Unit in the asbestos areas of the Cape and Transvaal (occupational and nonoccupational neighborhood exposure), 130 from the Cape and 25 from the Transvaal, out of a total sample of 2,590; (2) 120 cases certified on X-ray as asbestosis by the Miners' Medical Bureau, Johannesburg, 90 from the Cape and 30 from the Transvaal; (3) 50 post-mortem proven cases (mines) examined by the Pneumoconiosis Research Unit, Johannesburg; (4) 64 post-mortem proven cases from the United Kingdom (industry)
• Exposure: Asbestos. In the Cape areas the fiber was crocidolite and the population predominantly 'Coloured' (the article's term). In the Transvaal areas the fiber was predominantly amosite and the population mainly 'Bantu' (the article's term). The UK cases were occupationally exposed in industry.
• Main results:
  • Proposed code: linear opacities were divided into coarse (more than 1 mm in width, coded Lc) and fine (Lf). Their extent was graded 1/3, 2/3 and 3/3 by the area of lung involved, not by intensity.
  • Proposed code: calcified pleural plaques were given a place within the classification, because in asbestosis they are frequently enough to establish the diagnosis on X-ray
  • Proposed code: additional symbols were added for bronchial carcinoma (Ca), mesothelioma (Me) and cystic changes (Cy)
  • Population survey group (1): 155 cases were diagnosed as asbestosis, 130 from the Cape and 25 from the Transvaal, out of a total sample of 2,590. Asbestosis was printed as 6.2% for the Cape and 5.1% for the Transvaal.
  • Population survey group (1), Cape versus Transvaal: all pleural changes 94% vs 96%; calcified plaques only 43% vs 12%; all parenchymal changes 40% vs 84%; nodules 16% vs 44%
  • Certified group (2), Cape (90 cases) versus Transvaal (30 cases): calcified plaques 59% vs 36%; calcified plaques only 22% vs 2%. In the Transvaal, all pleural changes were 87% and all parenchymal changes 77%; the Cape figures are damaged in the scan.
  • The authors noted that both South African X-ray groups showed a similar trend towards parenchymal changes in the Transvaal
  • United Kingdom post-mortem group (4): all pleural changes 92%; calcified plaques 18%; calcified plaques only 2%
  • Comparing the UK figures with South African groups 1 and 2, the authors found that calcified plaques were apparently more frequent in South Africa
• The authors' conclusion: The authors concluded that the exchange of films and readings between the United Kingdom and South Africa had established the workability of the proposed code. They added that if the code is widely used, a standard set of films should be selected and made available, as was done for the I.L.O. classification.
• Limitations the authors state:
  • The split of linear markings into coarse and fine is purely arbitrary
  • The place of pleural thickening within the classification is tentative and subject to future statistical analysis
  • The cases in groups 1 and 2 were not pathologically proven
  • Groups 1 and 2 were drawn from different samples, one from the general population and one from the industry
  • The authors stated that whether the group differences have any profound significance was not the issue; the figures were meant to illustrate the code's practical use

Topics

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

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Pleural Plaques, Pleural Thickening, Carcinoma, Mesothelioma, Transvaal, Chest X-Ray, Crocidolite.

Related studies

• Radiological and pathological correlations in asbestosis in the Republic of South Africa and the United Kingdom. II. A preliminary study of observer variation in the classification of radiographs of asbestos-exposed workers and the relation of pathology and x-ray appearances — A. Caplan, J.C. Gilson, et al. (1965)
• Radiological classification of pulmonary asbestosis — H. Bohlig (1965)
• Asbestosis in South Africa--certain geographical and environmental considerations — G.K. Sluis-Cremer (1965)
• Factors influencing the reading of small irregular opacities in a radiological survey of asbestos miners in South Africa — G.K. Sluis-Cremer, P.A. Hessel, et al. (1989)
• Excess mortality from stomach cancer, lung cancer, and asbestosis and/or mesothelioma in crocidolite mining districts in South Africa — J.L. Botha, L.M. Irwig, et al. (1986)
• Risk of asbestosis in crocidolite and amosite mines in South Africa — L.M. Irwig, R.S. du Toit, et al. (1979)

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