FRI0475 Lung damage in patients with microscopic polyangiitis

Objectives We evaluated the frequency of clinical and CT features of lung damage in patients with microscopic polyangiitis (MPA). Methods We enrolled 97 patients with MPA, that was diagnosed according to CHCC2012. The median age at disease onset was 50.7±16.6 (M±SEM) years, the median duration of follow-up was 47.6±47.5 (M±SEM) months. 64 (66.0%) patients were ANCA-MPO-positive, 24 patients (24.7%) were ANCA-PR-3-positive, and 9 (9.3%) patients had undifferentiated ANCA. Diffuse alveolar haemorrhage (DAH) was diagnosed by the presence of dyspnea, hemoptysis, anaemia and pulmonary infiltrates on chest CT. Results Lung damage was diagnosed in 77 (79.4%) patients. 43 (55.8%) patients had pulmonary damage at the disease onset, while 34 (44.2%) patients developed signs of lung involvement within 8.0±4.1 (M±SEM) months. At baseline, the median pulmonary BVAS was 4. 2; 6 The interstitial changes occurred in more than half of cases at the onset of the disease. The most frequent CT-patterns included pulmonary infiltrates (n=49) and ground-glass opacity (n=39) (table 1). DAH developed in 30 (30.9%) patients, among them 15 (15.5%) had DAH at the onset of the disease. The pulmonary fibrosis was the most common CT-pattern at the end of follow-up (52 patients). Notably, interstitial damages at the onset of disease were associated with the development of fibrotic changes (OR=4.7, 95% CI 1.7–12.9) and bronchiectasis (OR=9.8, 95% CI 1.2–78.3) at the end of follow-up. The median of pulmonary VDI was 1 (0;4) at the end of the follow up. PR-3-positive group had higher occurrence of consolidations at the end of the follow-up as compared to patients with anti-MPO-antibodies (53.8% versus 16.0%, p=0.023). The pulmonary fibrosis was the most common CT-pattern at the end of follow-up (52 patients). Notably, interstitial damages at the onset of disease were associated with the development of fibrotic changes (OR=4.7, 95% CI 1.7–12.9) and bronchiectasis (OR=9.8, 95% CI 1.2–78.3) at the end of follow-up. The median of pulmonary VDI was 1 (0;4) at the end of the follow up. PR-3-positive group had higher occurrence of consolidations at the end of the follow-up as compared to patients with anti-MPO-antibodies (53.8% versus 16.0%, p=0.023). Conclusions In patients with MPA, the CT signs of interstitial damage were usually reversible. However, they predicted a higher incidence of lung fibrosis and bronchiectasis at the end of follow-up. DAH occured in one third of patients with MPA. Disclosure of Interest None declared