Pneumoconiosis combined with connective tissue disease in China: a cross-sectional study

Our plain-English summary of Pneumoconiosis combined with connective tissue disease in China: a cross-sectional study, by W. Xu, R. Ma, J. Wang, et al (BMJ Open, 2023).

The study

• Authors: W. Xu, R. Ma, J. Wang, D. Sun, S. Yu, Q. Ye
• Journal: BMJ Open
• Published: 2023;13(4):e068628
• Cited by: 10 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Objective: To describe the prevalence, clinical features and potential risk factors of pneumoconiosis in combination with connective tissue disease (CTD) or positive autoantibodies.

Design: Cross-sectional study.

Setting: A retrospective study of adults recruited in China between December 2016 and November 2021.

Participants: A total of 931 patients with pneumoconiosis at Beijing Chao-Yang Hospital were enrolled in this study; of these, 580 patients were included in the final analysis.

Main Outcome Measures: Pneumoconiosis combined with CTD or positive autoantibodies was a major adverse outcome.

Results: In total, 13.8% (80/580) of the patients had combined pneumoconiosis with CTD, among whom the prevalence of CTD was 18.3% (46/251) in asbestosis and 11.4% (34/298) in silicosis/coal mine workers' pneumoconiosis. In comparison to the general Chinese adult population, the relative risk of various CTD in pneumoconiosis, including rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, primary Sjögren's syndrome, idiopathic inflammatory myopathy and antineutrophil cytoplasmic antibodies-associated vasculitis, were 11.85, 12.12, 127.40, 4.23, 9.94 and 644.66, respectively. Multivariate analysis revealed that female sex (OR 2.55, 95% CI 1.56 to 4.17) and a later stage of pneumoconiosis (OR 2.04, 95% CI 1.24 to 3.34) were the independent risk factors for CTD in patients with pneumoconiosis (all p<0.050).

Conclusion: CTD is highly prevalent in patients with pneumoconiosis, especially in patients of asbestosis, and silicosis/coal mine workers' pneumoconiosis. Female sex and later stages of pneumoconiosis are associated with an increased risk of combined with CTD.

© Author(s) (or their employer(s)) 2023. 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 reviewed records of patients with pneumoconiosis (lung disease from inhaled mineral dust) recruited at Beijing Chao-Yang Hospital, China, between December 2016 and November 2021. Of 931 patients, 580 were analysed. All patients with asbestosis had been exposed to chrysotile asbestos. Eighty of the 580 (13.8%) had a connective tissue disease (CTD). The results text reports CTD in 18.3% of 251 patients with asbestosis and 11.4% of 298 with silicosis or coal workers' pneumoconiosis. However, the article's Table 2 and discussion give 298 asbestos-exposed and 251 silica-exposed patients, with fewer CTD cases in the asbestos group, so which group had the higher rate is unclear. Compared with published general-population figures, the six specific CTDs compared were more common in these patients, with relative risks such as 11.85 (95% CI 7.42 to 18.93) for rheumatoid arthritis. The authors concluded that female sex and stage II or III disease were independent risk factors for CTD. Women and later-stage patients also had higher odds of positive autoantibodies. The authors noted that the design cannot show cause and effect and that amphibole asbestos exposure was not covered.

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: Retrospective, hospital-based cross-sectional study of consecutively recruited patients
• Who was studied: 931 patients with pneumoconiosis at Beijing Chao-Yang Hospital, China, recruited December 2016 to November 2021; 580 analysed. The results text gives 298 with silicosis/coal mine workers' pneumoconiosis, 251 with asbestosis and 31 with other subtypes. The discussion and Table 2 instead give 298 with asbestosis and 251 with silicosis. Mean age 59.93 years; 180 (31%) female.
• Exposure: Occupational mineral dust: asbestos (all asbestosis patients exposed to chrysotile), silica/coal mine dust, and other dusts (e.g. welder's pneumoconiosis, anthracosis). Median exposure duration 19 years. Dust concentrations were not measured.
• Main results:
  • 80 of 580 patients with pneumoconiosis (13.8%) had CTD: 28 rheumatoid arthritis, 2 systemic lupus erythematosus, 7 systemic sclerosis, 19 primary Sjögren's syndrome, 7 ANCA-associated vasculitis, 4 idiopathic inflammatory myopathy, 12 unclassified CTD and 1 mixed CTD.
  • The results text reports CTD in 18.3% of 251 patients with asbestosis and 11.4% of 298 with silicosis/coal mine workers' pneumoconiosis. Table 2 instead lists 34 CTD cases among asbestos-exposed and 46 among silica-exposed patients, and the discussion gives 298 with asbestosis and 251 with silicosis, so the group assignment is internally inconsistent.
  • Rheumatoid arthritis: prevalence 4.83% in the pneumoconiosis patients vs 0.41% in the general population; relative risk 11.85 (95% CI 7.42 to 18.93)
  • Systemic lupus erythematosus: relative risk 12.12 (95% CI 2.03 to 72.47) vs the general population
  • Systemic sclerosis: relative risk 127.4 (95% CI 15.70 to 1033.76) vs the general population
  • Primary Sjögren's syndrome: relative risk 4.23 (95% CI 2.19 to 8.17) vs the general population
  • Idiopathic inflammatory myopathy: relative risk 9.94 (95% CI 6.37 to 15.52) vs the general population
  • ANCA-associated vasculitis: relative risk 644.66 (95% CI 316.76 to 1312.00) vs the general population
  • Patients with CTD had lower lung function than those without. Total lung capacity was 70.75% vs 84.31% of predicted (p<0.001), forced vital capacity 76.16% vs 85.10% (p=0.014) and diffusing capacity 58.68% vs 72.32% (p<0.001).
  • In multivariable analysis, risk factors for CTD were female sex (OR 2.55, 95% CI 1.56 to 4.17) and stage II or III pneumoconiosis (OR 2.04, 95% CI 1.24 to 3.34)
  • Exposure duration over 10 years (vs 0 to 10 years) was not statistically significantly associated with CTD in univariate analysis (OR 0.72, 95% CI 0.44 to 1.17, p=0.182)
  • 227 of 580 patients (39.1%) tested positive for autoantibodies
  • In multivariable analysis, risk factors for positive autoantibodies were female sex (OR 2.50, 95% CI 1.73 to 3.62) and stage II or III pneumoconiosis (OR 1.80, 95% CI 1.27 to 2.55)
• The authors' conclusion: The authors concluded that CTD prevalence in pneumoconiosis was as high as 13.8% (18.3% in asbestosis and 11.4% in silicosis, per their text). They also concluded that female sex and a later stage of pneumoconiosis were independent risk factors for pneumoconiosis with CTD.
• Limitations the authors state:
  • The cross-sectional design could not address whether pneumoconiosis causes CTD
  • The study could not identify factors affecting other organ involvement, malignancy or death
  • The sample size was based on silicosis data because there were no studies of CTD in asbestosis
  • No dust concentration data were available; years of exposure were used as a rough measure
  • Seronegative rheumatoid arthritis may have been missed
  • All asbestosis patients had chrysotile exposure, so the findings do not address amphibole asbestos exposure

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, Silicosis, Relative Risk, Idiopathic, Multivariate Analysis.

Related studies

• Association of occupational dust exposure with combined chronic obstructive pulmonary disease and pneumoconiosis: a cross-sectional study in China — Y. Fan, W. Xu, et al. (2020)
• The burden of pneumoconiosis in China: an analysis from the Global Burden of Disease Study 2019 — J. Li, P. Yin, et al. (2022)
• [A cross-sectional investigation on risk factors of lung cancer for residents over 40 years old in Chengdu, Sichuan Province, China] — B. Chen, W. Li, et al. (2010)
• Talc pneumoconiosis: a report of six patients with postmortem findings — M. Kleinfeld, C.P. Giel, et al. (1963)
• Talc pneumoconiosis — A.I. McLAUGHLIN, E. Rogers, et al. (1949)
• Mixed pneumoconiosis: silicosis, asbestosis, talcosis, and berylliosis — G.J. Mark, C.B. Monroe, et al. (1979)

Browse more research in BMJ Open, or return to medical research.