Diffuse interstitial pulmonary fibrosis and rheumatoid arthritis.

Diffuse interstitial pulmonary fibrosis in rheumatoid arthritis has received considerable attention since it was first described 20 years ago (Ellman and Ball, 1948). It appears that few authorities now doubt that the association is valid, despite the absence of statistical evidence from controlled investigations (Aronoff, Bywaters, and Fearnley, 1955; Talbott and Calkins, 1964; Stack and Grant, 1965). Locke (1963), in a radiographic study, did find an incidence of 28 per cent. compared with none in a control group, but this was a highly selected series of patients. Curiously, more support for the concept has arisen from uncontrolled observations such as those of Cruickshank (1959), Brannan, Goode, Divertie, and Baggenstoss (1964), Patterson, Harville, and Pierce (1965), and Thompson (1965), where a frequency varying from 1 1 to 5 per cent. has been found. The high incidence of rheumatoid factor in the sera of patients with interstitial pulmonary fibrosis even in the absence of rheumatoid arthritis (Turner-Warwick and Doniach, 1965) has further suggested a link between the two diseases. However, Scadding (1960) and Stack, Grant, Irvine, and Moffat (1965) did not find rheumatoid factor in their series. Whether the pulmonary lesions are a true systemic manifestation of rheumatoid arthritis or related in some other way is not yet known. As was recently stressed much controversy still surrounds the subject (Leading Article, 1967). The purpose of the investigation to be described was to re-examine the problem by studying a large series of unselected patients with rheumatoid arthritis and comparing them with a similar series with degenerative joint disease as a control group.