Clinical features of Crohn disease concomitant with ankylosing spondylitis

Extraintestinal manifestations (EIMs) cause increased morbidity and decreased quality of life in Crohn disease (CD). Ankylosing spondylitis (AS) belongs to EIMs. Very little is known on the clinical features of CD concomitant with AS. This study is to investigate the clinical features of CD patients with AS.We retrospectively collected all CD patients with AS in our hospital, and established a comparison group (CD without AS) with age, sex, and duration of Crohn disease matched. Clinical information was retrieved for comparison.Eight CD + AS patients were identified from 195 CD patients. Sixteen CD patients were randomly selected into comparison group. All CD + AS patients were male, HLA-B27 (+), and rheumatoid factor (-) with an average age of 40.8 ± 4.52 years. Significant correlation between disease activity of CD and AS was revealed (r = 0.857, P = 0.011). Significant correlation between disease activity of CD and functional limitation associated with AS was identified (r = 0.881, P < 0.01). C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and globulin were positively correlated to Crohn disease activity index (CDAI), Bath AS disease activity index, and Bath AS functional index(BASFI) scores (r = 0.73-0.93, P < 0.05). Albumin was negatively associated with CDAI and BASFI (r = -0.73 to -0.91, P < 0.05). The ratio of albumin to globulin (Alb/Glo) was significantly related to all 3 scores (r = -0.81 to -0.91, P < 0.05).Male predominance with a 4.12% concomitant incidence of AS is observed in CD patients. Disease activity of CD correlates with disease activity of AS and functional limitation caused by AS. CRP, ESR, and Alb/Glo may serve as biomarkers for disease activity and functional limitation in CD patients concomitant with AS, although future studies are expected.