Changes in pathologic findings of large and small airways have been reported in patients with scleroderma, but the prevalence and significance of functional abnormalities in the small airways have not been defined unequivocally. During the last years, high prevalence of SAD has been reported occasionally in scleroderma. However, most of the related studies are not controlled and include smoking patients, which probably affects the reported prevalence. Therefore, using the pulmonary function tests, we studied a group of nonsmoking patients with scleroderma and compared it with a group of nonsmoking age- and sex-matched controls, in an attempt to evaluate the presence of SAD in scleroderma.
Lung function may be abnormal in patients with scleroderma in the absence of pulmonary symptoms, clinical findings, or roentgenologic abnormalities. Therefore, the pulmonary function tests that we used in the present study are considered to be objective and the most sensitive among the noninvasive methods for the early detection of pulmonary involvement in scleroderma. In general, dynamic compliance, expiratory flow rates, closing volume (CV), RY and RV/TLC measurements have been usually used for the early detection of SAD.