Association of occupational dust exposure with combined chronic obstructive pulmonary disease and pneumoconiosis: a cross-sectional study in China

Our plain-English summary of Association of occupational dust exposure with combined chronic obstructive pulmonary disease and pneumoconiosis: a cross-sectional study in China, by Y. Fan, W. Xu, Y. Wang, et al (BMJ Open, 2020).

The study

• Authors: Y. Fan, W. Xu, Y. Wang, Y. Wang, S. Yu, Q. Ye
• Journal: BMJ Open
• Published: 2020;10(9):e038874
• Cited by: 36 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objectives: Occupational dust exposure may induce various lung diseases, including pneumoconiosis and chronic obstructive pulmonary disease (COPD). The features of combined COPD and pneumoconiosis have not been well described, and this may hamper the management. This study aimed to describe the prevalence and characteristics as well as the risk factors of the combined diseases.

Design: A cross-sectional study.

Setting And Participants: 758 patients with pneumoconiosis were recruited at a single-medical centre. Of these, 675 patients with pneumoconiosis, including asbestosis, silicosis, coal workers' pneumoconiosis and other pneumoconiosis, was eligible for analysis.

Primary Outcome Measures: COPD was diagnosed based on clinical features and/or history of exposure to risk factors and post bronchodilator forced expiratory volume in 1 s (FEV1)/forced vital capacity (FVC) ratio <0.7. Clinical data were collected from predesigned medical reports. The patients underwent both chest radiograph and high-resolution CT scans. Risk factors for combined COPD and pneumoconiosis were analysed using regression analysis.

Results: COPD prevalence overall was 32.7% (221/675) and was the highest in silicosis (84/221) and coal workers' pneumoconiosis (100/221). COPD prevalence increased with smoking pack-years, dust exposure duration and pneumoconiosis stage. Patients with combined diseases had lower body mass index, higher smoking index and worse pulmonary function. Risk factors for combined diseases included heavy smoking, silica or coal exposure and advanced pneumoconiosis. The interaction between dust exposure and smoking in COPD was also identified. The risk of combined COPD significantly increased with heavy smoking and silica or coal exposure (OR 5.49, 95% CI 3.04 to 9.93, p<0.001).

Conclusions: COPD is highly prevalent in patients with pneumoconiosis, especially patients with silicosis and coal workers' pneumoconiosis. Occupational dust exposure as well as heavy smoking is associated with an increased risk of combined COPD and pneumoconiosis, which demands an effective preventive intervention.

© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

In plain English

This cross-sectional study looked at 675 patients with pneumoconiosis (523 men) seen at Beijing Chao-Yang Hospital, China, between January 2016 and July 2019. They included 130 with asbestosis, 210 with silicosis, 259 with coal workers' pneumoconiosis and 76 with other types. COPD, identified by lung function testing, was found in 32.7% (221/675) overall. It was more common in silicosis (40.0%) and coal workers' pneumoconiosis (38.6%) than in asbestosis (23 of 130, 17.7%). It rose with smoking pack-years and with pneumoconiosis stage, reaching 62.6% in stage III. After adjusting for other factors, the odds of COPD compared with asbestos exposure were higher with silica exposure (OR 2.42, 95% CI 1.28 to 4.59) and coal exposure (OR 3.19, 95% CI 1.57 to 6.49). Similar results were seen in never-smokers. Smoking 20 or more pack-years and stage III disease were also associated with COPD, and the authors reported an interaction between dust exposure and smoking. The authors concluded these factors are associated with increased COPD risk. They noted the study used one hospital and that exposure levels were difficult to estimate because patients worked in different industries.

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: Cross-sectional (descriptive) study of consecutively recruited hospital patients
• Who was studied: 675 patients with pneumoconiosis (523 men), out of 758 invited, recruited at Beijing Chao-Yang Hospital, China, from January 2016 to July 2019. They comprised 130 with asbestosis, 210 with silicosis, 259 with coal workers' pneumoconiosis and 76 with other pneumoconiosis. Dust-exposed workers without pneumoconiosis were not studied.
• Exposure: Type of occupational dust (asbestos, silica, coal, other dust), duration of dust exposure, and cigarette smoking measured in pack-years. The article does not name asbestos fiber types. The authors state that occupational exposure levels were difficult to estimate.
• Main results:
  • Overall COPD prevalence among the 675 patients with pneumoconiosis was 32.7% (221/675)
  • COPD prevalence was 40.0% in patients with silicosis and 38.6% in patients with coal workers' pneumoconiosis
  • COPD prevalence in silicosis and coal workers' pneumoconiosis was about twice that in asbestosis (Table 2: 23 of 130 asbestosis patients, 17.7%)
  • COPD prevalence was 24.3%, 36.2% and 43.9% in patients smoking 1 to 9, 10 to 19 and 20 or more pack-years (p=0.002). It did not differ by sex, smoking history or BMI.
  • COPD prevalence was 20.2% in pneumoconiosis stage I, 25.6% in stage II and 62.6% in stage III (p less than 0.001)
  • In the multivariable analysis (651 patients, after excluding those with central large opacities), silica exposure was associated with higher odds of COPD than asbestos exposure: OR 2.42, 95% CI 1.28 to 4.59, p=0.007
  • In the same analysis, coal dust exposure compared with asbestos exposure: OR 3.19, 95% CI 1.57 to 6.49, p=0.001
  • Smoking 20 or more pack-years compared with never smoking was associated with COPD in the multivariable model: OR 1.91, 95% CI 1.10 to 3.32
  • Among never-smokers, compared with asbestos exposure, silica exposure had OR 3.88 (95% CI 1.49 to 10.12, p=0.006) and coal exposure had OR 3.85 (95% CI 1.12 to 13.18, p=0.032)
  • A significant interaction was found between dust exposure and smoking. The odds of COPD increased with heavy smoking combined with silica or coal exposure (OR 5.49, 95% CI 3.04 to 9.93, p less than 0.001). The article text does not state the comparison group.
  • Among the 221 patients with both COPD and pneumoconiosis, 31.7% had GOLD stage I COPD, 42.1% stage II, 20.8% stage III and 5.4% stage IV
• The authors' conclusion: The authors concluded that COPD was highly prevalent in patients with certain types of pneumoconiosis. They concluded that heavy smoking, silica or coal dust exposure and advanced pneumoconiosis are all associated with increased COPD risk, and that dust exposure interacts with smoking.
• Limitations the authors state:
  • Patients came from a single medical centre, and dust-exposed workers without pneumoconiosis were not studied
  • The cross-sectional design could not show the association between occupational exposure and disease progression or mortality
  • Because patients were employed in different industries, occupational exposure levels were difficult to estimate, and so was the exposure-response relationship in COPD prevalence
  • Passive smoking was not taken into account, so smoking effects might be underestimated
  • The study could not tell whether COPD began before or after pneumoconiosis
  • COPD may have been underestimated in patients with pneumoconiosis, especially asbestosis

Topics

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, COPD, Silicosis, FEV1, Chest X-Ray, High-Resolution CT (HRCT).

Related studies

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• Characteristics of airway obstruction severity in relation to air pollutant in asbestos-exposed chronic obstructive pulmonary disease individuals: A cross-sectional study — M. Yu, X. Lu, et al. (2026)
• Incident chronic obstructive pulmonary disease associated with occupation, industry, and workplace exposures in the Health and Retirement Study — S.R. Silver, W.A. Alarcon, et al. (2021)
• A somatic TSHR mutation in a patient with lung adenocarcinoma with bronchioloalveolar carcinoma, coronary artery disease and severe chronic obstructive pulmonary disease — J.W. Kim, S. Lee, et al. (2012)
• Respiratory impairments due to dust exposure: a comparative study among workers exposed to silica, asbestos, and coalmine dust — X. Wang, E. Yano, et al. (1997)
• WHO/ILO work-related burden of disease and injury: Protocol for systematic reviews of occupational exposure to dusts and/or fibres and of the effect of occupational exposure to dusts and/or fibres on pneumoconiosis — D. Mandrioli, V. Schlünssen, et al. (2018)

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