Comparison of chest radiograph reading methods for assessing progress of pneumoconiosis over 10 years in Wittenoom crocidolite workers

Our plain-English summary of Comparison of chest radiograph reading methods for assessing progress of pneumoconiosis over 10 years in Wittenoom crocidolite workers, by N.H. de Klerk, A.W. Musk, A. James, et al (British Journal of Industrial Medicine, 1990).

The study

• Authors: N.H. de Klerk, A.W. Musk, A. James, J.J. Glancy, W.O. Cookson
• Journal: British Journal of Industrial Medicine
• Published: 1990;47(2):127-31
• Type of article: Randomized trial
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000009).

Abstract

Thirty three pairs of chest radiographs taken up to 10 years apart were obtained for 33 subjects suffering from asbestosis who had applied for compensation to the Pneumoconiosis Medical Board of Western Australia. Multiple films from the period before the first radiograph in each pair, from the intervening period between the two, and from the period subsequent to the second radiograph were also available and all films were read by two independent readers according to the 1980 ILO classification of pneumoconiosis. Films were read twice as side by side pairs ten years apart, twice as two separate randomly ordered films ten years apart, and once as part of the full series of all available chest radiographs on each subject to assess which method provided the best consistency (between reader variation) and repeatability (within reader variation). Judging by consistency, the full series method performed as well as either of the other methods when assessing radiographic changes and significantly better when assessing the level of profusion of small opacities. There was little to choose between the other two methods either judging by consistency or repeatability, which could not be estimated for the full series method. Use of all available films for a subject is recommended for assessing single films, as in a prevalence study, as well as for documenting change in a longitudinal study.

In plain English

This study compared three ways of reading chest X-rays. The subjects were 33 of 384 men who had applied for compensation to the Pneumoconiosis Medical Board of Western Australia. All had been awarded some compensation for asbestosis, had been exposed to crocidolite from Wittenoom Gorge, and had films 10 years apart plus six to 21 others. Two readers scored the films by the 1980 ILO classification in three ways: each pair side by side, the two films separately in random order, or the pair within the man's full series. Agreement was measured as relative disagreement rates; lower means better. For the profusion of small opacities on the later film, the full series method gave better agreement between readers (rate 0.16, 95% CI 0.07 to 0.38, for disagreement by one major category) than the other two methods, which were equally good. For change over 10 years, agreement between readers was similar for all three methods. The authors recommended including more films where possible. They noted there is no absolute standard for the true degree of lung fibrosis, and repeatability could not be measured for the full series method.

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 comparison study of chest radiograph reading strategies. It measured agreement between two readers (consistency) and within each reader (repeatability) using log linear models.
• Who was studied: 33 of the 384 men who had applied for compensation to the Pneumoconiosis Medical Board of Western Australia. All had been awarded some compensation for asbestosis. Each had at least one pair of plain chest radiographs taken 10 years apart, plus between six and 21 additional films (average 13). The men started work between 1947 and 1965 (median 1955).
• Exposure: Crocidolite from Wittenoom Gorge, Western Australia. By workplace: mine only (14 men), mill only (7), mill and mine (5) and elsewhere (7). Median average intensity of exposure was 20 fibres/ml (range 5 to 110). Median duration of employment was 1430 days (range 70 to 6003). Median total cumulative exposure was 85 fibres/ml years.
• Main results:
  • For the level of profusion of small opacities on the later film of each pair, the full series method gave better agreement between readers than the pairs and random singles methods. Its relative disagreement rate was 0.16 (95% CI 0.07 to 0.38) for disagreement by one major category, with no disagreement of two or more.
  • The better performance of the full series method for single radiographs appeared statistically significant, based on a test of heterogeneity across methods. The pairs and random singles methods were equally good.
  • For within-reader agreement on single radiographs, the random singles method had a relative disagreement rate of 0.29, compared with 0.4 for the pairs method (disagreement by one major category). The authors said this difference could have been due to chance (p = 0.4).
  • For radiographic changes over 10 years, agreement between readers was similar for all three methods.
  • For within-reader agreement on changes, there was a significant interaction between reader and method (p = 0.01). The second reader had a much higher rate of disagreement using the pairs method.
• The authors' conclusion: The authors concluded that, judged by consistency between readers, using all available films was superior for assessing single films and at least as good for assessing progression. They recommended including greater numbers of films where possible.
• Limitations the authors state:
  • There is no independent, absolute standard for the true degree of pulmonary fibrosis, so the validity of the reading methods could not be tested directly.
  • Each reader read the full series only once, so repeatability could not be assessed for the full series method.
  • The amount of data did not allow two of the more complex disagreement models to be examined.
  • The older films were easy to recognise, so the temporal order of films could not be disguised.

Mines named here

Asbestos mines this study is about. Each mine's page says who ran it, when it worked, and what it produced.

• Wittenoom, Western Australia

All asbestos mines

Topics

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

Medical terms in this study, explained in our Lexicon: Chest X-Ray, Pneumoconiosis, Wittenoom, Crocidolite, ILO Classification.

Related studies

• Chest radiographs in subjects with asbestos-related abnormalities: comparison between ILO categorizations and clinical reading — B. Hilt, A. Borgerson, et al. (1992)
• Comparison of measures of exposure to asbestos in former crocidolite workers from Wittenoom Gorge, W. Australia — N.H. de Klerk, A.W. Musk, et al. (1996)
• Comparison of independent randomised reading of radiographs with direct progression scoring for assessing change in asbestos-related pulmonary and pleural lesions — G.H. McMillan, C.E. Rossiter, et al. (1982)
• Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia — W.O. Cookson, N.H. De Klerk, et al. (1986)
• Assessment of physicians' proficiency in reading chest radiographs for pneumoconiosis, based on a 60-film examination set with two factors constituting eight indices — T. Tamura, Y. Kusaka, et al. (2018)
• Malignant mesotheliomas in former miners and millers of crocidolite at Wittenoom (Western Australia) after more than 50 years follow-up — G. Berry, A. Reid, et al. (2012)

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