Usual interstitial pneumonia in rheumatoid arthritis-associated interstitial lung disease

Interstitial lung disease is a common manifestation of rheumatoid arthritis; however, little is known about factors that influence its prognosis. The aim of the present study was to determine whether or not the usual interstitial pneumonia pattern found on high-resolution computed tomography (HRCT) is of prognostic significance in rheumatoid arthritis-associated interstitial lung disease (RA-ILD). Patients with RA-ILD were identified retrospectively (n=82). The relationship of a definite usual interstitial pneumonia pattern on HRCT to survival was determined and compared to that in a cohort of patients with radiologically diagnosed idiopathic pulmonary fibrosis (n=51). A definite usual interstitial pneumonia pattern was seen in 20 (24%) out of 82 patients with RA-ILD. These patients showed worse survival than those without this pattern (median survival 3.2 versus 6.6 yrs), and a similar survival to those with idiopathic pulmonary fibrosis. On multivariate analysis, a definite usual interstitial pneumonia pattern on HRCT was associated with worse survival (hazard ratio of 2.3). Analysis of specific HRCT features demonstrated that traction bronchiectasis and honeycomb fibrosis were associated with worse survival (hazard ratio of 2.6 and 2.1, respectively). Female sex (hazard ratio of 0.30) and a higher baseline diffusing capacity of the lung for carbon monoxide (hazard ratio of 0.96) were associated with better survival. A definite usual interstitial pneumonia pattern on HRCT has important prognostic implications in RA-ILD.