Comparison of Relapsing Polychondritis Patients with and Without Respiratory Involvement Based on Chest Computed Tomography: A Retrospective Cohort Study

Background: Relapsing polychondritis (RP) patients with tracheal cartilage involvement are different from other patients. The objectives of this study were to compare the clinical features and disease patterns between respiratory involvement subgroup and non-respiratory involvement subgroup according to chest computed tomography. Method We performed a retrospective cohort study collected RP patients hospitalized at the Beijing Chao-Yang Hospital between January 2012 - August 2021. Results The incident of costochondritis was more frequent in RP patients with respiratory involvement(p=0.03), the incidence of inflammatory eye disease(p=0.001) and auricular chondritis(p=0.001) was less frequent in RP respiratory involvement patients, compared with those of RP patients without respiratory involvement. Correlation analysis showed that a negative correlation between respiratory involvement and auricular chondritis (r=-0.58, p < 0.01), and between respiratory involvement and inflammatory eye disease (r=-0.45, P < 0.01). Auricular chondritis was positively correlated with inflammatory eye disease (r=0.49, P < 0.01). Compared with non-respiratory involvement subgroup, the incidence of pulmonary infection marginally increased in respiratory involvement subgroup(p=0.06). Inflammatory indexes except for CAR were significantly higher in respiratory involvement subgroup, subgroup analysis found that there was no significant relationship between inflammatory indexes and pulmonary infection. Conclusion RP patients with respiratory involvement was characterized by higher rate of costochondritis and pulmonary infection, fewer inflammatory eye disease and auricular chondritis compared to non-respiratory involvement. Increase inflammatory indexes may suggested that patients with respiratory involvement had a higher disease activity index of RP. The probability of survival was not significant between two subgroups.