Background/Purpose: To investigate clinical characteristics of interstitial lung disease (ILD) in rheumatoid arthritis (RA) patients, and to analyze whether high resolutional CT (HRCT) can predict the outcome of ILD in RA.

Methods: 365 patients with RA were treated at our hospital and followed up at least one year. All patients were performed chest radiological examinations at the initial presentation. The HRCT findings which include (1) ground glass opacity, (2) air-space consolidation, linear opacity including (3) septal line and (4) non-septal line, (5) honeycomb lung, (6) traction bronchiectasis, (7)pleural irregularity, and (8)pleural effusion were scored as the CT scoring system. The extent of involvement of each abnormality was assessed independently for each of the three zones of each lung. The HRCT extent score was represented the sum of the score of each lung. HRCT parameters which include the extension score and the clinical features at the initial presentation were retrospectively analyzed.

Results: 177 out of 355 patients had abnormal chest radiological findings which included bronchiectasis, bronchitis and ILD (49.8%). 91 (26 male(39.3%), 65 female(22.4%)) out of 355 patients showed ILD at initial presentation (25.6%). 5 out of 91 patients had shortness of breath and showed a rapidly progressive ILD (5.5%). In HRCT findings, ILD in these 5 cases were widely spread at the initial presentation. The rest of 86 patients   showed no progression of ILD and asymptomatic. However there were no difference in the HRCT findings which include nonseptal linear attenuation, ground-glass attenuation and air space consolidation between rapidly progressive ILD group and asymptomatic group, rapidly progressive ILD group showed more higher degree in honeycombing (p=0.0002) and extensive ILD (p=0.007). Prognosis of the rapidly progressive ILD was variable. The rapidly progressive ILD are treated with immunosuppressive agent which include high dose steroid, cyclophosphamide, azathioprine, cyclosporineA (CsA) and Mycophenolate Mofetil(MMF) for IP. 2 patients treated with CsA and one patient treated with MMF shows improving of ILD on HRCT. But in other 2 patients were resistant to these immunosuppressive agents.

Conclusion: HRCT findings focused on the extension score at the initial presentation is a useful predictor of the outcome of ILD in RA. And this study suggests that RA patients with preexisting honeycombing lung  must be aware of rapidly progressive ILD.