Materials and Methods
Thirty-one nonsmoking consecutive patients (28 female, three male) with definite progressive systemic sclerosis according to the American Rheumatism Association criteria were studied. All the patients satisfied the single major criterion for classification of definite progressive systemic sclerosis (proximal scleroderma). The 31 patients were classified as having diffuse cutaneous systemic sclerosis or the limited cutaneous form of the disease according to the classification of LeRoy. All the patients were questioned for symptoms and examined for clinical and roentgenologic findings as well as serologic features reflecting pulmonary involvement of the disease. Thirty-one age- and sex-matched volunteer control subjects were studied in parallel. All the control subjects were lifelong nonsmokers.
Patients and controls were excluded from the study if they had the following: (1) a clinical history of asthma, bronchitis, or emphysema; (2) a professional exposure to lung irritants; (3) lung cancer; and (4) a history of ischemic heart disease, systemic hypertension, or congestive heart failure. None of the patients had ever taken medication for pulmonary disease.