Predictors for Improvement of Global Functioning in Patients with Axial Spondyloarthritis

Objectives: We aimed to investigate the factors associated with changes in the global functioning of patients with axial spondyloarthritis (axSpA) and to identify predictors of improvement. Methods: One-hundred-and-eighty-five patients enrolled in the Incheon Saint Mary's axSpA prospective observational cohort were evaluated. Global functioning was assessed at baseline and at 1-year follow-up using the ASAS health index (HI). Improvement was defined as a reduction in the ASAS HI of ≥3. Physical function was assessed using the Bath Ankylosing Spondylitis Functional Index (BASFI). Disease activity measures included Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Ankylosing Spondylitis Disease Activity Score (ASDAS), and C-reactive protein (CRP) levels. Predictors of improved global functioning were identified by logistic regression analysis. Results: Nineteen patients (10%) showed improved global functioning at 1-year follow-up versus baseline. Univariate linear regression analysis identified body mass index at baseline, the use of TNF inhibitors, a change in the BASFI and BASDAI, and changes in CRP levels as being associated with changes in the ASAS HI. Multivariate analysis revealed that changes in the BASFI and BASDAI were associated independently with a change in the ASAS HI. Univariate logistic regression analysis revealed that a decrease in the BASFI, BASDAI, ASDAS, and CRP levels predicted improved global functioning. Multivariate analysis identified a decrease in the BASFI and BASDAI as a significant predictor of improved global functioning (odds ratio (95% CI) = 1.465 (1.006-2.135) and 1.414 (1.044-1.914), respectively). Conclusions: Changes in physical function and disease activity were associated independently with changes in global functioning assessed by the ASAS HI in axSpA. A decrease in the BASFI and BASDAI was a significant predictor of improvement in the ASAS HI.