Background: Respiratory disability induced by dust exposure in coal workers is assessed by pulmonary function tests and radiological evidence of pneumoconiosis. High-resolution computed tomography (HR-CT) improves the visibility of tissue changes, but the value of the findings for the clinical evaluation is controversial. Objectives: It was the aim of this study to evaluate the correlation between the International Labour Office (ILO) classification and the degree of emphysema in HR-CT with self-reported dyspnea and pulmonary function tests including diffusion capacity for CO (DL,CO). Methods: We investigated 87 coal miners (aged 67 ± 6 years), having worked underground for 26 ± 9 years, with pulmonary function tests and HR-CT. Univariate associations were tested with correlation coefficients, and multivariable analyses used a stepwise forward regression model. Results: No aspect of the ILO classification showed a univariate correlation with dyspnea or forced expiratory flow in 1 s (FEV1). Emphysema CT score was strongly associated with DL,CO (rs = –0.40; p < 0.001) and FEV1/maximal vital capacity (r = –0.38; p < 0.001) in univariate analysis, but not with the clinical grade of dyspnea (r = –0.14; p = 0.256). CT emphysema score but not ILO classification was associated with FEV1 in multivariable analyses (rs = –0.37; p < 0.001). Dyspnea was best approximated by DL,CO (r = –0.312; p = 0.008). Conclusion: The clinical grade of breathlessness was best approximated by DL,CO. HR-CT showed a good association with expiratory flow limitation. ILO classification of the chest radiograph may be a marker of exposure but conveys little information about the degree of respiratory impairment.

Keywords:
Occupational lung disease, Pneumoconiosis, Chronic bronchitis, Chronic obstructive pulmonary disease
1.
American Thoracic Society: Adverse effects of crystalline silica exposure. Am J Respir Crit Care Med 1997;155:761–768.
2.
Fisher ER, Watkins G, Lam NV: Objective pathological diagnosis of coal workers’ pneumoconiosis. JAMA 1981;245:1829–1834.
3.
Cockcroft AE, Seal RME, Wagner JC: Postmortem study of emphysema in coalworkers and non-coalworkers. Lancet 1982;2:600–603.
4.
Cooper JK, Johnson TP: Exercise capacity in coal workers’ pneumoconiosis: an analysis using causal modeling. Br J Ind Med 1990;47:52–57.
5.
Violante B, Brusasco V, Buccheri G: Exercise testing in radiologically limited simple pulmonary silicosis. Chest 1986;90:411–415.
6.
Cotes JE, Zejda J, King B: Lung function impairment as a guide to exercise limitation in work-related lung disorders. Am Rev Respir Dis 1988;137:1089–1093.
7.
Musk AW, Bevan C, Campbell MJ, Cotes JE: Factors contributing to the clinical grade of breathlessness in coalworkers with pneumoconiosis. Bull Eur Physiopathol Respir 1979;15:343–353.
8.
Ferris BG: Epidemiology standardization project: recommended respiratory disease questionnaires for use with adults and children in epidemiological research. Am Rev Respir Dis 1978;118:7–54.
9.
International Labour Office: Guidelines for the use of ILO classification of radiographs of pneumoconiosis. Geneva, International Labour Office, 1995.
10.
Foster WL, Pratt PC, Roggli V, Godwin JD, Halvorsen RA, Putman CE: Centrilobular emphysema: CT-pathologic correlation. Radiology 1986;159:27–32.
11.
Quanjer PH, Tammeling GJ, Cotes JE, Pedersen OF, Peslin R, Yernault JC: Lung volumes and forced ventilatory flows. Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official statement of the European Respiratory Society. Eur Respir J 1993;6:5–40.
12.
Cotes JE, Chinn DJ, Quanjer PH, Roca J, Yernault JC: Standardization of the measurement of transfer factor (diffusing capacity). Report Working Party Standardization of Lung Function Tests, European Community for Steel and Coal. Official statement of the European Respiratory Society. Eur Respir J 1993;6:41–52.
13.
Pauwels RA, Buist AS, Calverley PM, Jenkins CR, Hurd SS, the GOLD Scientific Committee: Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease. NHLBI/WHO Global Initiative for Chronic Obstructive Lung Disease (GOLD) Workshop summary. Am J Respir Crit Care Med 2001;163:1256–1276.
14.
Gevenois PA, Sergent G, De Maertelaer V, Gouat F, Yernault JC, De Vuyst P: Micronodules and emphysema in coal mine dust or silica exposure: relation with lung function. Eur Respir J 1998;12:1020–1024.
15.
Collins LC, Willing S, Bretz R, Harty M, Lane E, Anderson W: High-resolution CT in simple coal workers’ pneumoconiosis. Lack of correlation with pulmonary function tests and arterial blood gas values. Chest 1993;104:1156–1162.
16.
Cotes JE, Chinn DJ, Reed JW, Hutchinson JEM: Experience of a standardised method for assessing respiratory disability. Eur Respir J 1994;7:875–880.
17.
Bestall JC, Paul EA, Garrod R, Garnham R, Jones PW, Wedzicha JA: Usefulness of the Medical Research Council (MRC) dyspnoea scale as a measure of disability in patients with chronic obstructive pulmonary disease. Thorax 1999;54:581–586.
18.
Sue DY, Oren A, Hansen JE, Wasserman K: Diffusing capacity for carbon monoxide as a predictor of gas exchange during exercise. N Engl J Med 1987;316:1301–1306.
19.
Cotton DJ, Soparkar GR, Grahan BL: Diffusing capacity in the clinical assessment of chronic airflow limitation. Med Clin North Am 1996;80:549–564.
20.
Bauer TT, Schultze-Werninghaus G, Schmidt EW, Kollmeier J, Weber A, Eibel R, Lemke B: Ventilatory response to sub-maximal exercise in patients with low-grade coal workers’ pneumoconiosis. Occup Environ Med 2001;58:794–799.
21.
Kinsella M, Müller N, Vedal S, Staples C, Abboud RT, Chan-Yeung M: Emphysema in silicosis. Am Rev Respir Dis 1990;141:1497–1500.
22.
Begin R, Filion R, Ostiguy G: Emphysema in silica- and asbestos-exposed workers seeking compensation. A CT scan study. Chest 1995;108:647–655.
23.
Ooi GC, Tsang KW, Cheung TF, Khong PL, Ho IW, Ip MS, Tam CM, Ngan H, Lam WK, Chan FL, Chan-Yeung M: Silicosis in 76 men: qualitative and quantitative CT evaluation – Clinical-radiologic correlation study. Radiology 2003;228:816–825.
24.
Park KJ, Bergin CJ, Clausen JL: Quantitation of emphysema with three-dimensional CT densitometry: comparison with two-dimensional analysis, visual emphysema scores, and pulmonary function test results. Radiology 1999;211:541–547.
25.
International Labour Office: Guidelines for the use of the ILO international classification of radiographs of pneumoconiosis. Geneva, International Labour Office, 2002.
© 2007 S. Karger AG, Basel
2005
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.