Small Airways Dysfunction in Systemic Sclerosis

A debate exists regarding the importance of small airways disease in systemic sclerosis, while smoking seems to have a major effect on the exact prevalence. In order to evaluate small airways dysfunction (SAD) in a pure systemic sclerosis population, we performed pulmonary function studies in 31 nonsmoking patients and 31 age- and sex-matched nonsmoking control subjects. Patients’ FVC, TLC, and Dco mean values were significantly lower compared with the corresponding values of the controls (p<0.05), while there was no difference in MEF25, RV, and RV/TLC. Seven (22.6 percent) of 31 patients and four controls (a nonsignificant difference) had evidence of SAD, namely a maximum expiratory flow at 25 percent of vital capacity (MEF25) less than 60 percent of predicted. Positive correlation (p<0.001) was found between MEF25 and FEV₁/FVC in the patients. Moreover, no differences were found in abnormal lung function patients with and those without SAD in demographic, clinical, roentgenologic, and serologic features and results of pulmonary function tests. These findings suggest that SAD in our patients is not a characteristic and early manifestation of systemic sclerosis and that, when present, it is not correlated with the severity of the pulmonary involvement in scleroderma.