Body mass index is related with the presence of syndesmophyte in axial spondyloarthritis: Data from the Korean College of Rheumatology BIOlogics (KOBIO) registry

Objective: We investigated whether body mass index (BMI) is associated with parameters of disease activity and clinical manifestations in axial spondyloarthritis (axSpA). Methods: Demographic, clinical, and radiological features and disease activity indexes from 789 axSpA patients (619 males and 170 females) were obtained from the Korean College of Rheumatology BIOlogics (KOBIO) registry. BMI (kg/m(2)) was classified into normal (BMI < 23.0), overweight (23.0 <= BMI < 25.0), and obese (BMI >= 25.0). Disease activity indexes included Bath ankylosing spondylitis disease activity index (BASDAI), erythrocyte sediment rate (ESR), C-reactive protein (CRP), and ankylosing spondylitis disease activity score (ASDAS). Results: The mean BMI in patients with axSpA was 23.3 +/- 3.5. 50.2% of all patients were overweight or obese. Overweight/obese patients had more syndesmophyte and less peripheral arthritis than those in normal BMI patients (p<0.001 and p<0.030, respectively). BMI was not associated with disease activity indexes in axSpA patients. Patients with syndesmophyte had higher BMI than those without syndesmophyte (24.2 +/- 3.6 vs. 22.9 +/- 3.3, p<0.001). Multivariate logistic regression analysis showed that increased BMI was closely related with the presence of syndesmophyte (OR = 1.086, 95% CI 1.031-1.143, p = 0.002) Conclusions: Our results imply that increased BMI is significantly associated with the presence of syndesmophyte, but not with disease activity in axSpA.