Longitudinal changes in pulmonary function of asbestos workers

Our plain-English summary of Longitudinal changes in pulmonary function of asbestos workers, by X. Wang, M. Wang, H. Qiu, et al (Journal of Occupational Health, 2010).

The study

• Authors: X. Wang, M. Wang, H. Qiu, I. Yu, E. Yano
• Journal: Journal of Occupational Health
• Published: 2010;52(5):272-7
• Cited by: 18 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Objective: To observe the longitudinal changes in pulmonary function associated with exposure to asbestos in a group of highly exposed workers.

Methods: Pulmonary diffusing capacity (DLco) and spirometry of 243 Chinese asbestos workers were measured and remeasured after 5 and 10 yr. Their annual changes in relation to cumulative asbestos exposure and asbestosis were determined using multivariate analysis.

Results: The greatest annual decline was observed in DLco, particularly in workers with asbestosis, followed by FVC and FEV(1). A greater decline in DLco accorded with a higher level of cumulative asbestos exposure. A similar trend was also seen in FVC, in which the highest exposure level was associated with 223 ml loss over each 5 yr period or 45 ml/yr.

Conclusions: There were substantial declines in DLco and FVC over time in the asbestos workers, and a dose-response trend between asbestos exposure and accelerating functional loss.

In plain English

This study followed 243 male workers at a Chinese factory that used chrysotile asbestos to make textiles and building materials. Lung function was tested in 1995 and retested after 5 years (125 workers) and 10 years (124 workers). Gas transfer in the lungs (DLco) was measured only at the first two tests. Across all workers over 5 years, DLco fell most, about 5% a year. The breathing measures FVC and FEV1 followed, at about 3% a year. Workers with asbestosis at the start (66 at baseline, 50 retested at 5 years) had a faster DLco decline but a slower FEV1 decline over 5 years than those without. DLco fell 47% faster in the second-highest quarter of cumulative dust exposure and 72% faster in the highest quarter than in the lowest, but the trend tests were not statistically significant. In an analysis using all three tests, the highest exposure quarter's FVC estimate was -222.83 ml relative to the lowest quarter (95% confidence interval -501.89 to -56.22). The authors described this as 223 ml lost each 5-year period. They concluded that the results suggest a dose-response trend. They noted loss to follow-up, small subgroups and no unexposed comparison group.

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: Longitudinal study of one factory workforce, with lung function measured at baseline and repeated 5 and 10 years later
• Who was studied: 243 male active or retired workers from an asbestos product factory in China, tested in 1995. 125 returned at 5 years and 124 at 10 years, and 174 (72%) gave at least two measurements. 66 had asbestosis at baseline (50 of them retested at 5 years and 40 at 10 years), and no new cases were diagnosed during follow-up.
• Exposure: Chrysotile used to make asbestos textiles and asbestos building materials (asbestos cement, tiles). Total dust in work areas always exceeded 3 mg/m3 and personal fiber samples exceeded 3 fibers/ml. Average exposure was 14 years at baseline, and mean cumulative personal dust exposure was 1,373 mg·yr.
• Main results:
  • All workers: the greatest annual decline over 5 years was in DLco (5%), followed by FVC and FEV1 (3% each). The results persisted after adjustment for age, height and smoking.
  • Workers with asbestosis (n=50 at the 5-year retest) had a faster DLco decline and a slower FEV1 decline over 5 years than workers without asbestosis (n=75)
  • DLco declined 47% faster in the second-highest and 72% faster in the highest quartile of cumulative dust exposure than in the lowest quartile
  • None of the trend tests across exposure quartiles was statistically significant
  • In the GEE analysis using all three measurements over 10 years, the highest (4th) quartile of cumulative dust exposure had an FVC estimate of -222.83 ml relative to the lowest quartile (95% CI -501.89 to -56.22). The authors described this as an FVC decline of 223 ml each 5-year period, or 45 ml per year.
  • When cumulative dust exposure was left out of the models, each work-year was associated with a 12.9 ml decline in FVC (95% CI -21.47 to -4.36)
• The authors' conclusion: The authors concluded that the results suggest a dose-response trend between the intensity of asbestos exposure and accelerating loss of lung function in asbestos workers
• Limitations the authors state:
  • Loss to follow-up: at 5 years, the workers who returned differed from those who did not, which may have somewhat overestimated the decline over the first 5 years
  • Small sample size, especially in subgroup analyses, which may explain the non-significant differences
  • No unexposed control group, so the declines might be partly explained by aging

Topics

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

Medical terms in this study, explained in our Lexicon: Diffusing Capacity (DLCO), Spirometry, Asbestos Exposure, Multivariate Analysis, Dose-response relationship.

Related studies

• Lung function among asbestos cement factory workers: cross-sectional and longitudinal study — A. Siracusa, C. Cicioni, et al. (1984)
• Pulmonary function in long-term asbestos workers in China — X.R. Wang, E. Yano, et al. (2001)
• Effect of postoperative radiotherapy on changes in pulmonary function in patients with stage II and IIIA lung carcinoma — N.C. Choi, D.J. Kanarek, et al. (1990)
• TruCutR needle biopsy in asbestosis and silicosis: correlation of histological changes with radiographic changes and pulmonary function in 41 patients — P. Tukiainen, E. Taskinen, et al. (1978)
• Radiographic changes and lung function in relation to activity of the glutathione transferases theta and mu among asbestos cement workers — K. Jakobsson, A. Rannug, et al. (1995)
• Longitudinal decline in lung function in former asbestos exposed workers — E. Algranti, E.M. Mendonça, et al. (2013)

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