Background: Dyspnea is a symptom that is difficult to evaluate, especially in occupational diseases. Objective: To evaluate the relationship between chronic dyspnea, in its varying degrees of severity, and the functional repercussions for dysfunction or incapacitation in former workers with asbestosis. Method: A total of 40 former workers diagnosed with asbestosis were evaluated. Dyspnea scores were determined using the modified Medical Research Council scale, the 1984 and 1993 American Medical Association scales, and the Baseline Dyspnea Index. Spirometry, measurement of diffusion capacity for carbon monoxide and cardiopulmonary exercise tests (incremental and submaximal) were also performed. Results: Based on scores obtained using the Medical Research Council and 1984 American Medical Association scales, respectively, 72.5% and 67.5% of the subjects were classified as dyspneic, compared with 37.5% and 31.6%, respectively, using the 1993 American Medical Association and Baseline Dyspnea Index scales. There was greater concordance between the Medical Research Council and 1993 American Medical Association scales, as well as between the 1984 and 1993 American Medical Association scales, when the categories of "absent" and "mild" were grouped. No significant relation was found between dyspnea, as determined by each of the scales, and functional abnormalities - either at rest or during exercise. Conclusion: In individuals with asbestosis, the degree of concordance among the available dyspnea scales varies significantly. There is a real need for dyspnea indices that evaluate respiratory dysfunction at rest and during exercise.

Keywords: Asbestosis/diagnosis. Dyspnea/physiopathology. Spirometry/methods.