AB0360B ANALYSIS OF SEQUENTIAL DEVELOPMENT OF PULMONARY LESIONS IN PATIENTS WITH RHEUMATOID ARTHRITIS

Background Pulmonary involvement is critical for the management of RA. Pulmonary involvement shows various features in pathology and imaging such as interstitial pneumonia (ILD) and airway diseases (ADs). Importantly, pulmonary abnormalities coexist with other ones. We have previously reported that there were coexpstence patterns and ADs were shared abnormalities of patients with pulmonary lesions. However, it remains unknown through what pathways various pulmonary lesions develop. Objectives The purpose of this study was to determine the sequential development of pulmonary abnormalities in RA. Methods A retrospective cohort study. Subjects were consecutive 208 RA patients who were treated with bDMARDs as the first one from Feb.2004 to Sep. 2015 in our department and received HRCT scan before and during the therapy. Based on HR-CT imaging, pulmonary abnormalities were classified into 4 categories (ILD, nodular lesions, airway disease (AD) and others) and 20 lesions such as ground-glass opacity (GGO), reticular pattern, bronchiolitis and bronchiectasis. We recorded their existence and distribution and examined their changes. Cluster analysis was conducted according to new lesions at the second CT scans during the biological DMARDs, by Ward method. A checkerboard analysis with Chi-square test followed by residual analysis was conducted to examine the relation between pre-existing and newly emerging lesions. We compared the frequencies and pattern of newly emerging lesions in patients with or without pre-existing lesions. Results Subjects were 208 RA patients; M/F; 64/144, mean age; 59.2 years old, disease duration; 7.9 years, positive for RF in 84.1%. bDMARDs used for the longest period were TNF inhibitors in 79.8% of the subjects, abatacept in 15.4% and tocilizmab in 4.8%. Pulmonary abnormalities were found in 146 (70.2%) of patients at the entry (ILD 81, (38.9%); nodular lesions 45, (21.6%); and AD 115, (55.3%)). During the observation period (3.26±2.61 years), newly emerging pulmonary lesions were found in 31.3% of patients and the incidence of which was 11.1/100 person-year. Cluster analysis of newly emerging lesions showed 7 clusters (Fig.1); Cluster 1; no new lesions, Cluster 2; nodular lesions, Cluster3; curved linear opacities, Cluster 4; bronchioectasis, Cluster 5; consolidations, Cluster 6; new bronchiolitis, and Cluster 7; GGO. Newly emerging lesions frequently occurred in patients with pre-existing pulmonary lesions. Notably, curved linear opacities and bronchiolitis were developed in patients without pre-existing lesions with high frequencies compared to those with pre-existing ones (Fig.1). In patients with pre-existing lesions, various lesions were developed, particiraly GGO and consolidation. The checkerboard analysis of pre-existing and newly emerging lesions revealed relation between 1) pre-existing honeycomb, small nodular lesions, bronchiolitis or bronchioectasia and newly emerging GGO and 2) pre-existing nodules and new bronchial wall thickening. In addition, bronchoectasia has the tendency to develop in patients with bronchitis, and conversely bronchiolitis occurred in patients with bronchioectasia. The relation between pre-existing small nodules or bronchiolitis and GGO was shown by analysis of pre-existing lesions and clusters of newly emerging ones. Conclusion Pulmonary lesions were developed in several patterns, not at random. Pre-existing pulmonary abnormalities induced new pulmonary lesions. Airway diseases, particularly bronchiolitis, might be important initial lesions that induce new pulmonary lesions, especially GGO. Disclosure of Interests None declared