Seropositive rheumatoid arthritis associated with decreased diffusion capacity of the lung.

Sixty-two patients with classical or definite rheumatoid arthritis were subjected to lung function analysis. The various parameters--spirography, plethysmography, blood gas analysis, measurement of lung compliance, and diffusion capacity--were correlated with duration and stage of disease, and with rheumatoid factor titres. A statistically significant correlation was found to exist between Rose-Waaler titre and specific diffusion capacity. Similar results between Rose-Waaler titre and lung compliance, however, were not statistically significant.