Comparative Effectiveness of Secukinumab and Adalimumab in Ankylosing Spondylitis: A Retrospective Study

Background: Ankylosing spondylitis (AS) is a chronic inflammatory disease within the axial spondyloarthritis spectrum. Biological therapies targeting tumor necrosis factor-alpha (TNF-α) and interleukin-17A (IL-17A) have expanded treatment options for patients with persistent disease activity. Objective: To compare the effectiveness of secukinumab and adalimumab in patients with AS and to compare each biological therapy with conventional disease-modifying antirheumatic drugs (DMARDs) over one year. Methods: This retrospective comparative study included 83 patients: 31 receiving secukinumab 150 mg, 28 receiving adalimumab 40 mg, and 24 receiving DMARDs. C-reactive protein (CRP) was evaluated at weeks 16, 24, and 52. Disease activity at week 52 was assessed using the Ankylosing Spondylitis Disease Activity Score based on CRP (ASDAS-CRP), and clinical response was evaluated using the Assessment of SpondyloArthritis International Society 20% response criteria (ASAS20) at weeks 24 and 52. Statistical significance was set at p < 0.05. Results: At week 16, CRP differed significantly between secukinumab and DMARDs (p = 0.003). At weeks 24 and 52, CRP differed significantly between both biological treatment groups and DMARDs (week 24: secukinumab p = 0.009, adalimumab p = 0.013; week 52: secukinumab p = 0.017, adalimumab p = 0.012). Direct comparisons between secukinumab and adalimumab were not significant. At week 52, both secukinumab (RR = 1.902, p = 0.045) and adalimumab (RR = 1.816, p = 0.038) were associated with a higher likelihood of low disease activity compared with DMARDs. Secukinumab was associated with ASAS20 response compared with DMARDs at week 52 (RR = 1.82, p = 0.021); the direct comparison with adalimumab was not significant. Conclusion: Both biological therapies were associated with more favorable inflammatory and disease-activity outcomes than DMARDs in this cohort. No statistically significant differences were demonstrated between secukinumab and adalimumab. The retrospective design and small sample size limit causal interpretation.