Improvement of Function and Its Determinants in a Group of Axial Spondyloarthritis Patients Treated with TNF Inhibitors: A Real-Life Study

Introduction The aim of this work is to investigate the improvement of physical function and its determinants in axial spondyloarthritis (SpA) patients treated with tumor necrosis factor (TNF) inhibitors in a real clinical practice setting. Methods An observational study was conducted in patients with axial SpA treated with anti-TNF from 2010 to 2018 with a minimum 6 months of follow-up. All patients fulfilled ASAS or the modified New York criteria. The Bath Ankylosing Spondylitis Metrology Index (BASMI) and the Bath Ankylosing Spondylitis Functional Index (BASFI) were used as objective and self-reported functional indices. The improvement of function and factors associated were evaluated for the present study, as well as disease activity and patient-reported outcome measures. Results A total of 183 patients with axial SpA were examined. Among them, 27 were non-radiographic axial SpA, while the remaining 156 were ankylosing spondylitis patients. BASFI and BASMI significantly improved during follow-up. Improvement of metrology index BASMI inverse correlated with disease duration (rho - 0.2, p = 0.009) and directly correlated with the improvement of BASDAI (rho 0.26, p = 0.003) and CRP (rho 0.26, p = 0.0003). Improvement of BASFI significantly inversely correlated with disease duration and directly correlated with the improvement of BASDAI, CRP, and baseline ESR. Male sex, lower disease duration, high ESR, and the improvement of BASDAI were found to be associated with the improvement of BASFI. Conclusions Our results showed that in real-life settings, patients improve in BASMI and BASFI. Furthermore, factors associated with this improvement were identified.