Radiographic progression of asbestosis: preliminary report

Our plain-English summary of Radiographic progression of asbestosis: preliminary report, by A. Gregor, R.W. Parkes, R. du Bois, et al (Annals of the New York Academy of Sciences, 1979).

The study

• Authors: A. Gregor, R.W. Parkes, R. du Bois, M. Turner-Warwick
• Journal: Annals of the New York Academy of Sciences
• Published: 1979;330:147-56
• Cited by: 19 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. 004031).

Abstract

In a collaborative study with the Pneumoconiosis Medical Panel, 232 asbestos workers were seen between 1967 and 1975. During this time, 50 of the 232 (21.5%) workers dies, 33 (13.8%) from respiratory disease probably related to asbestos exposure [10 (4.3%) pleural mesothelioma, three (1.3%) peritoneal mesothelioma, 10 (4.3%) asbestosis, 10 (4.3%) carcinoma of the lung]. Of the 182 survirors, 119 were recalled for other studies, and follow-up data were obtained as additional information at the same time, over a 1--7 year period. Paired radiographs were read, and 21 patients (17.6%) had worsened. As expected, the frequency of progression increased with a longer follow-up time, so that about one third of the subjects displayed progression after a minimum follow-up of 6 years. Ten of 73 patients (13.6%) had progressed in 3 years or less and may be defined as rapid progressors. No particular clinical feature distinguished clearly between progressors and nonprogressors, but there was a trend toward a greater frequency and higher titer of ANA among the progressors in this group. There was also a higher frequency of progression in those who were initially classified radiographically as 1/1 of 1/2 than in those with other initial radiographic appearances. This pilot study is now forming the basis for a larger, longer-term comprehensive survey.

In plain English

This preliminary report followed asbestos workers who applied to the Pneumoconiosis Medical Panel in London for pension assessment and were seen at the Brompton Hospital from 1967. They had worked as laggers, dockyard workers, shipwrights and in asbestos product manufacture, and most had been heavily exposed. Of 232 workers, 119 were recalled, and chest X-rays taken 1 to 7 years apart were compared. Lung shadowing had worsened in 21 of the 119 (17.6%). Progression became more common with longer follow-up, reaching about one third of those followed longest, though numbers were very small. Ten of 73 workers reviewed within 3 years had progressed. Progression was most frequent (10 of 34) among workers whose first X-ray showed slight but definite abnormality. No clinical feature clearly separated progressors from non-progressors. A trend toward more antinuclear antibodies among progressors was not statistically significant. By January 1977, 50 of the 232 had died. Death certificates for 46 of them listed mesothelioma in 13 (10 pleural, 3 peritoneal). The authors concluded that many cases of asbestosis did not progress with uniform rapidity.

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 (pilot) follow-up study of chest X-ray progression, with the paired X-rays of each worker read by two readers who did not know which film was taken first; deaths were traced through the Births and Deaths Register and death certificates
• Who was studied: 232 people who had worked with asbestos and applied to the Pneumoconiosis Medical Panel (London) for pension assessment, seen at the Brompton Hospital between 1967 and 1975. Of these, 119 were recalled for a separate study of HLA antigens, chosen in matched pairs with and without X-ray evidence of asbestosis, and were followed for 1 to 7 years. The authors describe the population as a selected one.
• Exposure: Occupational asbestos exposure among laggers, dockyard workers, shipwrights and workers manufacturing asbestos products. Fiber types are not named. Exposure was not calculated as fiber counts; a crude index based on job descriptions was used, and most had been heavily exposed.
• Main results:
  • Of the 119 workers seen twice, 21 (17.6%) showed worsening on paired X-ray reading.
  • The frequency of progression rose with length of follow-up, to about one third of those followed longest (the results section says at least 7 years, the summary says a minimum of 6 years). Numbers in the longer follow-up periods were very small.
  • The authors estimated the progression rate in this population as roughly linear at about 4% per year.
  • Among 73 workers followed for 1 to 3 years, 10 (13.6%) had progressed; the authors termed these rapid progressors.
  • Progression by initial X-ray category was 7 of 60 (11.7%) for 0/0 to 1/0, 10 of 34 (29.4%) for 1/1 to 2/1, and 4 of 25 (16.0%) for 2/2 to 3/3. Those with slight but definite abnormality had the highest frequency.
  • Clinical features of the 21 progressing workers and 50 non-progressing workers showed no statistical difference.
  • Antinuclear antibodies (ANA) showed a trend toward greater frequency and higher titers in the progressing group, but the trend was not statistically significant.
  • Of the 232 workers, 50 (21.5%) had died by January 30, 1977. Of 46 deaths with death certificates, 13 (28.3%) were certified as mesothelioma: 10 pleural and 3 primary peritoneal. Ten (21.7%) died of asbestosis or related cardiopulmonary complications, and 10 of bronchial carcinoma.
  • The 10 pleural mesothelioma deaths occurred among the 123 workers with minimal or no evidence of lung fibrosis. All 3 peritoneal mesotheliomas occurred among the 109 workers with asbestosis (category 1/1 or more).
  • Of 39 workers with an initial category greater than 1/1 followed for 3 to 7 years, 30 (76.9%) showed no progression. Among those with severe asbestosis (2/2 and greater), 13 of 16 showed no progression.
• The authors' conclusion: The authors concluded that, while the follow-up data gave cause for concern, many cases of asbestosis did not progress with uniform rapidity. They described the work as a pilot study forming the basis for a larger, longer-term survey.
• Limitations the authors state:
  • The population was a selected one (workers referred to a pension panel). For this reason the authors did not consider a formal mortality study of excess deaths appropriate.
  • Numbers were very small in the longer follow-up periods.
  • The failure to find clinical features distinguishing progressors may partly reflect small numbers.
  • Whether the rapid progressors keep progressing rapidly can only be judged with further X-rays.
  • Pleural shadows were not yet analyzed.
  • Lung function measurements were incomplete and were not reported.
  • Exposure could not be calculated as fiber counts; only a crude job-based index was used.

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, Asbestos Exposure, Pleural Mesothelioma, Peritoneal Mesothelioma, Carcinoma.

Related studies

• Radiographic progression of asbestosis — H. Suoranta, M.S. Huuskonen, et al. (1982)
• Follow-up of asbestosis patients and predictors for radiographic progression — P. Oksa, M.S. Huuskonen, et al. (1998)
• Late progression of radiographic changes in Canari chrysotile mine and mill exworkers — J.R. Viallat, C. Boutin, et al. (1983)
• Compensation, radiographic changes, and survival in applicants for asbestosis compensation — W.O. Cookson, A.W. Musk, et al. (1985)
• Radiographic asbestosis is not a prerequisite for asbestos-associated lung cancer in Ontario asbestos-cement workers — M.M. Finkelstein (1997)
• Prevalence of radiographic asbestosis in crocidolite miners and millers at Wittenoom, Western Australia — W.O. Cookson, N.H. De Klerk, et al. (1986)

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