Follow-up of asbestosis patients and predictors for radiographic progression

Our plain-English summary of Follow-up of asbestosis patients and predictors for radiographic progression, by P. Oksa, M.S. Huuskonen, J. Järvisalo, et al (International Archives of Occupational and Environmental Health, 1998).

The study

• Authors: P. Oksa, M.S. Huuskonen, J. Järvisalo, M. Klockars, A. Zitting, H. Suoranta, A. Tossavainen, K. Vattulainen, P. Laippala
• Journal: International Archives of Occupational and Environmental Health
• Published: 1998;71(7):465-71
• Cited by: 6 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: We followed a group of 85 Finnish asbestosis patients radiographically for an average of 6.5 (range 2-10) years to examine the progression of the disease and to assess possible explanations for the progression.

Methods: The examinations included full-size chest radiographs and a blood specimen analysis. The radiographs were classified according to the 1980 International Labor Office (ILO) classification. Progression was accepted if the second or third radiography was estimated (in a side-by-side comparison) to have more profusion of small opacities qualitatively than the first, even if the radiographs were classified into the same profusion category.

Results: In all, 38% of the patients showed progression during the follow-up period. The average progression of small opacities ranged from ILO 1/1 to ILO 2/2 (0.4 minor ILO categories/year). The asbestosis was progressive more often among the sprayers than among the insulators and asbestos factory workers [cross-tabulation, odds ratio (OR) 5.0, 95% confidence interval (95% CI) 1.2-20]. In the logistic regression model the ILO classification category at the beginning of the follow-up (OR 1.54; 95% CI 0.96-2.47), the fibronectin (OR 1.01; 95% CI 1.00-1.01) and angiotensin-converting enzyme (ACE; OR 1.10; 95% CI 1.00-1.20) levels, and the erythrocyte sedimentation rate (ESR; OR 1.05; 95% CI 1.00-1.10) were statistically associated with the radiographic progression of small opacities. Abnormalities of the pleura were found to progress more often among the patients with progressive parenchymal opacities.

Conclusion: For the progression of small-opacity profusion the significant predictors in the logistic regression model were the ILO profusion category at the beginning of the follow-up period, the fibronectin level, the ACE value, and the ESR. The model correctly classified 94% of the patients with progression and 65% of those without progression. The differences in the mean values recorded for the biomarkers between the progressors and nonprogressors, however, were small and may therefore not be of any importance to the clinician.

In plain English

This Finnish study followed 85 asbestosis patients who had at least two chest X-rays, for an average of 6.5 years. They included asbestos sprayers (in Finland, crocidolite was mainly used for spraying), insulators, asbestos cement factory workers, and asbestos quarry and other asbestos workers. X-rays were graded on the 1980 ILO scale, and blood markers were measured. Lung scarring (small opacities) progressed in 32 of the 85 patients (38%), on average from ILO 1/1 to ILO 2/2. Progression occurred in 7 of 11 sprayers and in 12 of 46 insulators and cement factory workers (odds ratio 5.0, 95% CI 1.2 to 20). Sprayer status was not a significant predictor in the regression model. In the 59 patients with complete blood tests, fibronectin, angiotensin-converting enzyme, sedimentation rate and starting ILO category were reported as predictors. For starting category the odds ratio was 1.54 (95% CI 0.96 to 2.47). Pleural changes progressed more often when lung opacities progressed. The authors concluded that the blood markers varied too widely to be useful for individual patients.

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: Radiographic follow-up study of asbestosis patients, with logistic regression to look for predictors of progression
• Who was studied: 85 Finnish asbestosis patients (78 men, 7 women), out of 128 reported to the Finnish Institute of Occupational Health in 1979 to 1987, who visited the institute at least twice. Average follow-up was 6.5 years (range 2 to 10). Complete blood marker data were available for 59.
• Exposure: Occupational asbestos exposure. Sprayers mainly used crocidolite, cement factories mainly chrysotile, and insulation workers were exposed to chrysotile, anthophyllite and amosite. Some patients worked at an anthophyllite quarry. Mean exposure duration was 21 years in both groups.
• Main results:
  • Small-opacity profusion progressed in 32 (38%) of the 85 patients
  • Among patients with progression, the mean change was from ILO 1/1 to ILO 2/2 (an average of 0.4 minor ILO categories per year)
  • Progression occurred in 65% (7/11) of asbestos sprayers, 26% (12/46) of insulators and asbestos cement factory workers, and 45% (13/28) of quarry and other asbestos workers
  • In cross-tabulation, the odds ratio for progression was 5.0 (95% CI 1.2 to 20) for sprayers versus insulators/factory workers. Sprayer versus nonsprayer was not a significant predictor in the logistic regression model.
  • In the logistic regression model (59 patients), the odds ratios were 1.01 for fibronectin (95% CI 1.00 to 1.01) and 1.10 for angiotensin-converting enzyme (95% CI 1.00 to 1.20). For erythrocyte sedimentation rate the odds ratio was 1.05 (95% CI 1.00 to 1.10). For ILO category at the start of follow-up it was 1.54 (95% CI 0.96 to 2.47, P 0.059).
  • 38% (12/32) of patients with progression had a starting ILO profusion of 1/2 or higher, compared with 8% (4/53) of patients without progression
  • The model correctly classified 94% of patients with progression and 65% of those without (total 82%)
  • 50% of patients with progressive small-opacity profusion had progressive pleural changes, compared with 4% of those without progression (OR 26, 95% CI 5.3 to 123)
  • Pleural calcifications were more common among patients without progression (58%) than among those with progression (31%)
  • In the 34 patients who did not develop cancer, the authors reported fibronectin and ESR as the significant predictors. For ESR the odds ratio was 1.10 (95% CI 0.978 to 1.23, P 0.079).
• The authors' conclusion: The authors concluded that progression occurs more often in heavily exposed occupations and that low-degree profusion is less likely to progress. They found that patients with progressive lung changes more often also have progressive pleural changes. They judged that the blood markers vary too widely to be useful for individual patients and cannot be recommended for routine diagnostics.
• Limitations the authors state:
  • The ILO 1980 classification used lacks sensitivity for detecting diffuse fibrosis compared with high-resolution CT
  • Missing laboratory values reduced the regression analysis to 59 patients

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, Insulator, Odds Ratio, confidence interval, ILO Classification, Pleura, Biomarker.

Related studies

• Progression of asbestosis predicts lung cancer — P. Oksa, M. Klockars, et al. (1998)
• Radiographic progression of asbestosis — H. Suoranta, M.S. Huuskonen, et al. (1982)
• Absence of radiographic asbestosis and the risk of lung cancer among asbestos-cement workers: Extended follow-up of a cohort — M.M. Finkelstein (2010)
• Regarding "absence of radiographic asbestosis and the risk of lung cancer among asbestos-cement workers: extended follow-up of a cohort", by Murray Finkelstein, American Journal of Industrial Medicine 2010 — R.M. Ross (2011)
• Radiographic progression of asbestosis: preliminary report — A. Gregor, R.W. Parkes, et al. (1979)
• Workers with Libby amphibole exposure: retrospective identification and progression of radiographic changes — T.C. Larson, C.A. Meyer, et al. (2010)

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