Correlation between respiratory symptoms and pulmonary function in asbestos-exposed workers

Our plain-English summary of Correlation between respiratory symptoms and pulmonary function in asbestos-exposed workers, by C.A. Brodkin, S. Barnhart, G. Anderson, et al (The American Review of Respiratory Disease, 1993).

The study

• Authors: C.A. Brodkin, S. Barnhart, G. Anderson, H. Checkoway, G.S. Omenn, L. Rosenstock
• Journal: The American Review of Respiratory Disease
• Published: 1993;148(1):32-7
• Cited by: 29 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Studies of respiratory questionnaire efficacy have emphasized reliability of responses; few have validated symptom response with objective measures of pulmonary function. To determine whether respiratory symptoms are associated with diminished pulmonary function, symptoms reported on the American Thoracic Society (ATS-DLD-78A) questionnaire were correlated cross-sectionally with measured spirometric volumes in 816 asbestos-exposed workers. Cough, phlegm, wheeze, and dyspnea were inversely related to pulmonary function. Cough, phlegm, and chronic bronchitis were associated with a 2 to 8% reduction (p < 0.001) in predicted values for forced vital capacity (FVC) and forced expiratory volume (FEV1); wheeze and dyspnea were clinically more significant, with an 11 to 17% reduction (p < 0.001). Wheeze, dyspnea, and roentgenographic fibrosis were all significant independent predictors of risk for restrictive impairment. These results support the validity of the ATS questionnaire as an epidemiologic tool and emphasize the importance of clinical history in assessing respiratory status.

In plain English

This cross-sectional study compared questionnaire-reported symptoms with spirometry in 816 asbestos-exposed men from a Seattle lung-cancer prevention trial, enrolled 1985 to 1988. 81% had worked at least 5 years in high-risk trades. Workers reporting wheeze or breathlessness (dyspnea) had predicted forced vital capacity (FVC) and FEV1 11 to 17% lower than those without; for cough and phlegm, 2 to 8% lower. Analyzed together with smoking and X-ray findings, only wheeze and dyspnea remained significant among the symptoms, each linked to 7 to 10% lower predicted FVC and FEV1. In adjusted analyses, wheeze (odds ratio 2.2, 95% CI 1.7 to 2.8) and dyspnea (odds ratio 2.6, 95% CI 2.0 to 3.3) were associated with restrictive impairment. Wheeze was linked to a lower FEV1/FVC ratio, but smoking, not any symptom, was significantly associated with obstructive impairment. The authors concluded these symptoms are associated with lower lung capacity in asbestos-exposed populations. Their stated limitations: the cohort may not be representative, the design cannot show whether symptoms predict later impairment or when they arise, and spirometry may misclassify restriction.

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 analysis comparing questionnaire-reported respiratory symptoms with spirometry
• Who was studied: 816 men aged 45 to 74 enrolled June 1985 to October 1988 in the Seattle Asbestos Lung Center Chemoprevention Trial, part of the Beta-Carotene and Retinol Efficacy Trial. They were recruited via physicians, unions, workers' compensation programs, the U.S. Navy and attorneys. Mean age was 58.
• Exposure: Occupational asbestos exposure (fiber types not specified). 661 (81%) had at least 5 years in high-risk trades: asbestos workers; shipyard boilermakers, electricians, shipfitters and ship scalers; plumbers and pipefitters; and sheet metal workers. The remaining 155 (19%) also had occupational exposure, with radiographic changes suggesting substantial cumulative doses. Mean employment in trade was 25 years (range 2.5 to 57).
• Main results:
  • Compared with workers not reporting the symptom, workers reporting wheeze or dyspnea had 11% and 13% lower predicted FVC, and 16% and 17% lower predicted FEV1. For cough and phlegm the differences were 5% and 2% for FVC, and 8% and 6% for FEV1.
  • In models including all symptoms, smoking and asbestos-related variables, only wheeze and dyspnea were statistically significant predictors among the symptom variables. Each was associated with 7 to 10% lower predicted FVC and FEV1. Smoking and asbestos-related variables were also associated with some lung-function measures.
  • In the full models, wheeze was also associated with a significantly lower FEV1/FVC, estimated at 5% of predicted, and with increased bronchodilator response, estimated at 3%.
  • Smoking status and asbestos-related findings did not confound the relationship between symptoms and lung function.
  • In logistic regression, wheeze (odds ratio 2.2, 95% CI 1.7 to 2.8) and dyspnea (odds ratio 2.6, 95% CI 2.0 to 3.3), but not cough or phlegm, were associated with increased risk of restrictive impairment.
  • In logistic regression for obstruction-only impairment, smoking (odds ratio 3.5, 95% CI 1.8 to 6.5) was associated with increased risk, but no respiratory symptom was.
  • The volume loss associated with wheezing and dyspnea (340 to 390 ml) was about equal to a decade of age-related decline (360 to 400 ml). It was greater than the 230 ml reduction associated with X-ray evidence of interstitial fibrosis.
  • Among asbestos-related variables, pleural thickening was associated with a 4% lower predicted FVC. Interval from first exposure was associated with an estimated 2% decline in predicted FVC and FEV1 per decade.
• The authors' conclusion: The authors concluded that cough, phlegm, wheeze and dyspnea are associated with significantly lower ventilatory capacity in asbestos-exposed populations. They found wheeze and dyspnea to be especially significant predictors of ventilatory impairment, independent of smoking.
• Limitations the authors state:
  • Because participants were recruited from a variety of sources, the cohort may not be representative of other asbestos-exposed groups.
  • The cross-sectional design does not allow conclusive statements about the predictive value of symptoms, or about when symptoms occur relative to the development of impairment.
  • Using spirometry rather than static lung volumes may have misclassified some restrictive impairment.
  • The design does not allow conclusions about whether wheezing represents an asbestos-related effect on small airways.

Topics

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

Medical terms in this study, explained in our Lexicon: Dyspnea, FEV1, Fibrosis.

Related studies

• Longitudinal pattern of reported respiratory symptoms and accelerated ventilatory loss in asbestos-exposed workers — C.A. Brodkin, S. Barnhart, et al. (1996)
• Malignant peritoneal mesothelioma presenting with respiratory symptoms — M. Daskalogiannaki, P. Prassopoulos, et al. (2000)
• Longitudinal analysis of respiratory symptoms in population studies with a focus on dyspnea in marine transportation workers — V.H. Arrandale, M. Koehoorn, et al. (2009)
• Effect of tale dust inhalation on lung function — M. Kleinfeld, J. Messite, et al. (1965)
• Lung function and respiratory symptoms in subjects with asbestos-related disorders: a cross-sectional study — B. Hilt, J.T. Lien, et al. (1987)
• Asbestosis, pulmonary symptoms and functional impairment in shipyard workers — K.H. Kilburn, R. Warshaw, et al. (1985)

Browse more research in The American Review of Respiratory Disease, or return to medical research.