Interstitial lung disease in patients with rheumatoid arthritis: a comparison with cryptogenic fibrosing alveolitis

Objectives. There is a lack of information on the natural history of patien ts with rheumatoid arthritis (RA) and associated interstitial lung disease (ILD). However, cryptogenic fibrosing alveolitis (CFA) is known to have a p oor long-term prognosis. As part of a longitudinal prospective study, we co mpared baseline characteristics in 18 patients with RA-ILD and 18 patients with CFA matched for age, sex and symptoms. We wished to establish whether there were significant baseline differences in clinical, physiological or r adiological parameters. Methods. A diagnosis of ILD was confirmed by high-resolution computed tomog raphy (HRCT) and supported by clinical and physiological findings in all pa tients. A number of clinical, immunological, physiological and radiological parameters were compared between the two groups. The median age in each gr oup was 77 yr and 10 patients in each group were male. Results. Twelve of the RA patients had smoked in excess of 10 pack yr as co mpared with nine patients with CFA (not significant). Clubbing was found in five patients with RA-ILD and in 14 with CFA (P=0.008). Pulmonary function tests showed no significant differences between the groups in forced expir atory volume in 1s, vital capacity or gas transfer factor. HRCT showed more ground glass shadowing and peripheral disease in RA patients, but more est ablished basal disease in those with CFA. Additionally, HRCT evidence of ho neycombing was associated with an absence of rheumatoid factor and a low ga s transfer factor. Conclusions. Clubbing is more common in patients with CFA, while RA-ILD pat ients have a higher prevalence of rheumatoid factor. Together with the diff erences in baseline HRCT, these variables in two groups of patients with si milar physiological impairment at baseline may be important predictors of o utcome in the longer term.