Obesity Increases Disease Activity of Norwegian Patients with Axial Spondyloarthritis: Results from the European Map of Axial Spondyloarthritis Survey

Objective: To investigate the prevalence of overweight and obesity, as well as the association between body mass index (BMI) and disease activity in patients with axial spondyloarthritis (axSpA).

Methods: Norwegian axSpA patients from the European Map of Axial Spondyloarthritis (EMAS) survey were included in this analysis. Sociodemographic, anthropomorphic, and disease-related variables (HLA-B27, comorbidities, BASDAI, and self-reported spinal stiffness) were reported. Patients were categorized into under/normal weight (BMI < 25 kg/m²), overweight (BMI ≥ 25 to < 30 kg/m²), and obese (≥ 30 kg/m²).

Results: Of the 509 participants in the EMAS survey, 35% were categorized as under/normal weight, 39% overweight, and 26% obese. Compared to under/normal-weight patients, overweight patients had significantly higher degree of spinal stiffness (mean (SD) 7.91 ± 2.02 vs 7.48 (2.15) and number of comorbidities (2.45 ± 2.11, vs 1.94), both p < 0.001. Obese patients had significantly higher disease activity (BASDAI mean (SD) 5.87 ± 1.78 vs 4.99 ± 2.08, p < 0.001), degree of spinal stiffness (8.18 ± 2.03 vs 7.48 ± 2.15, p = 0.006), and number of comorbidities (3.43 ± 2.43 vs 1.94. ± .38, p < 0.001) than under/normal weight patients. After adjusting for gender and age, obesity proved to be independently associated with disease activity.

Conclusion: Obesity was associated with higher reported BASDAI score, and being overweight or obese was associated with a higher degree of spinal stiffness and number of comorbidities compared to under/normal weight respondents. The results highlight the serious impact of obesity on health status, and obesity should therefore be considered as a modifiable risk factor for disease activity within the disease management of axSpA.

Keywords: Axial spondyloarthritis; Body mass index; Disease activity; Obesity.