Diagnostic value of exercise testing in asbestosis

Our plain-English summary of Diagnostic value of exercise testing in asbestosis, by J. Zejda (American Journal of Industrial Medicine, 1989).

The study

• Author: J. Zejda
• Journal: American Journal of Industrial Medicine
• Published: 1989;16(3):305-19
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 000181).

Abstract

The diagnostic value of simple exercise testing was examined in 81 current male asbestos-cement workers, divided into four groups according to the International Labour Office (ILO) category of irregular opacities: 0/0, 25; 1/1, 24; 1/2, 22; and 2/2, 10 men. An increasing X-ray score was accompanied by more severe functional abnormality in keeping with the development of a restrictive defect. Symptom-limited oxygen uptake (VO2SL) did not depend on the X-ray grade and was 76.7, 71.9, 68.7, and 73.5% pv, respectively, for the four groups. Subjects with ILO score 1/1 had significantly higher exercise ventilation at O2 uptake of 1.01.min-1 (VE 1.0) than those with grade 0/0. End-exercise tidal volume (VTSL in 1) decreased with an increasing X-ray score: 2.14, 1.98, 1.85, and 1.62, respectively. VTSL standardized for vital capacity (VTSL/VC) followed the same pattern. Asbestosis was diagnosed in 25 men, in whom VE 1.0 was significantly higher (p less than .02) and VTSL lower (p less than .01) than in the 0/0 group. VO2SL was similar in both groups. The findings suggest that VE 1.0 and VTSL may be early functional indicators of asbestos-related interstitial lung fibrosis. The measurement of both exercise indices may increase the certainty of clinical diagnosis of asbestosis in subjects with less advanced disease.

In plain English

This study in Sosnowiec, Poland, examined whether simple bicycle exercise tests help diagnose asbestosis. The author studied 81 male production workers from an asbestos cement factory who had been referred for suspected small irregular opacities on chest X-rays. The article does not name the asbestos fiber type. Workers were grouped by X-ray category (0/0, 1/1, 1/2, 2/2), and 25 met the author's criteria for asbestosis. Oxygen uptake at maximum tolerated exercise did not depend on X-ray grade. Breathing (ventilation) at a set level of exercise was significantly higher in the 1/1, 1/2 and 2/2 groups than in the 0/0 group. End-exercise tidal volume fell as X-ray scores rose. Men with asbestosis showed both differences compared with the 0/0 group. These differences were no longer significant after men with chronic bronchitis were excluded. The author concluded that exercise testing did not add much beyond the X-ray but could increase certainty of diagnosis in less advanced asbestosis. The author noted the small, selected group and possible effects of smoking.

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: Clinical study comparing lung function and exercise test results across groups of workers defined by chest X-ray category and by a clinical diagnosis of asbestosis
• Who was studied: 81 male production workers aged 24 to 66 from an asbestos cement factory, referred to the Institute of Occupational Medicine in the Mining and Metallurgical Industry, Sosnowiec, Poland, for suspected small irregular opacities on chest X-rays. Groups by ILO category: 0/0, 25 men; 1/1, 24; 1/2, 22; 2/2, 10. Men with cardiovascular disease or ECG abnormalities limiting exercise were not included.
• Exposure: Work in asbestos cement production for 3 to 28 years. Airborne asbestos dust concentrations ranged from 0.9 to 23.6 mg/m3 and fiber concentrations from 0.02 to 2.69 fibers per ml. The fiber type is not stated.
• Main results:
  • Group mean symptom-limited oxygen uptake ranged from 68.7 to 76.6% of predicted across the four X-ray groups and did not depend on the X-ray reading.
  • Ventilation at an oxygen uptake of 1.0 litre per minute was similar in the 1/1, 1/2 and 2/2 groups and significantly higher than in the 0/0 group (p less than .05).
  • End-exercise tidal volume decreased with increasing X-ray score: 2.14, 1.98, 1.85 and 1.62 litres for the 0/0, 1/1, 1/2 and 2/2 groups. The 2/2 group was significantly lower than the 0/0 group (p less than .01).
  • Asbestosis was diagnosed in 25 men. Compared with the 0/0 group they were significantly older (48.9 vs 41.6 years) and had longer exposure (20.7 vs 13.6 years).
  • Group mean symptom-limited oxygen uptake was 68.8% of predicted in the asbestosis group, compared with 76.6% of predicted in the 0/0 group.
  • After standardization for age, the difference in oxygen uptake between the asbestosis group and the 0/0 group was not statistically significant.
  • The ventilatory cost of exercise was significantly higher in the asbestosis group than in the 0/0 group (25.5 vs 22.9 litres per minute; p less than .02).
  • The asbestosis group had significantly lower end-exercise tidal volume than the 0/0 group (p less than .01).
  • Chronic bronchitis was diagnosed in 10 men with asbestosis and 6 men in the 0/0 group. After excluding them (15 with asbestosis, 19 in the 0/0 group), the exercise differences were no longer significant.
  • For asbestosis, sensitivity was 0.48 for raised exercise ventilation (above 25.0 litres per minute) and 0.64 for low end-exercise tidal volume relative to vital capacity (below 45%).
  • For asbestosis, the likelihood ratio was 2.4 for raised exercise ventilation and 1.6 for low end-exercise tidal volume relative to vital capacity.
• The authors' conclusion: The author concluded that the study does not show that exercise testing adds much to diagnosing asbestosis beyond the X-ray. The author also concluded that it can yield additional information to increase the certainty of clinical diagnosis in less advanced stages.
• Limitations the authors state:
  • Subjects were selected because of suspected asbestos-related X-ray abnormalities, and the number of subjects was rather small.
  • Lung-function results may have been substantially affected by smoking.
  • The exercise indices were associated with lung abnormalities that had already been detected by standard X-ray, which limits their practical use in diagnosis.
  • Chronic bronchitis might partly explain the exercise results, but the groups left after excluding men with bronchitis were too small for a firm conclusion.

Topics

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

Medical terms in this study, explained in our Lexicon: Asbestos-Cement, Interstitial, Fibrosis.

Related studies

• Role of exercise testing in assessing functional respiratory impairment due to asbestos exposure — J. Howard, Z. Mohsenifar, et al. (1982)
• Spiroergometric parameters at maximal exercise testing assessed functional respiratory impairment in asbestos-induced fibrosis — J. Schneider, R. Arhelger, et al. (2014)
• Cardiorespiratory responses to incremental exercise in patients with asbestos-related pleural thickening and normal or slightly abnormal lung function — A. Miller, A. Bhuptani, et al. (1993)
• Exercise impairment in asbestos-induced pleural fibrosis. Is it really just interstitial fibrosis? — E.T. Mannix, W.J. Martin (1994)
• Evaluation of breathlessness in asbestos workers. Results of exercise testing — P. Agostoni, D.D. Smith, et al. (1987)
• Exercise alveolar-arterial oxygen pressure difference in interstitial lung disease — C. Risk, G.R. Epler, et al. (1984)

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