[Usefulness of DLco for the early diagnosis of pulmonary involvement in collagen diseases].

Collagen disease are chronic multisystemic disorders affecting many organs. Pulmonary involvement is frequently associated with these collagen diseases. The usefulness of the diffusion capacity of the lung for the early detection of pulmonary involvement was assessed in 182 collagen vascular disease patients. In addition, the clinical characteristics of those patients with pulmonary lesions were also evaluated. Among these, there were 69 cases of chronic rheumatoid arthritis (RA), 39 progressive systemic sclerosis (PSS), 24 systemic lupus erythematosus (SLE), 12 dermatomyositis-polymyositis (DM-PM), 12 mixed connective tissue disease (MCTD), 11 Sjögren syndrome (SS), 9 Behçet's disease (BD) and 6 unclassified connective tissue disease (UCTD). Patients with normal chest X-ray but with pulmonary dysfunction were recognized in 56% of RA, 59% of PSS, 50% of SLE, 50% of DM-PM, 71% of MCTD, 33% of SS, and 50% of BD cases. Moreover, a higher degree of immunological abnormalities was observed in those with pulmonary complications. From these results, we conclude that diffusion lung capacity is a useful index for the early diagnosis of pulmonary involvement in collagen vascular disorders.