Factors associated with ASDAS remission in a long-term study of ankylosing spondylitis patients under tumor necrosis factor inhibitors

OBJECTIVE: To determine the clinical and demographic factors associated with disease remission and drug survival in patients with ankylosing spondylitis (AS) on TNF inhibitors. METHODS: Data from a longitudinal electronic database of AS patients under anti-TNF therapy between June/2004 and August/2013. Demographic, clinical parameters, disease activity by ASDAS remission (< 1.3) and inactive/low (< 2.1) were analyzed to characterize reasons for drug survival and switching of anti-TNF. RESULTS: Among 117 AS patients, 69 (59%) were prescribed only one anti-TNF, 48 (41%) switched to a second anti-TNF and 13 (11%) to a third anti-TNF. Considering ASDAS-CRP < 1.3, 31 (39%) patients were inactive at the end of the study. Non-switchers (P = 0.04), younger age (P = 0.004), non-smoking (P = 0.016), shorter disease duration (P = 0.047), more frequent use of SSZ (P = 0.037) and lower BASDAI (P = 0.027), BASMI (P = 0.034) and BASFI (P = 0.003) at baseline were associated with remission. In the multivariate analysis younger age (P = 0.016) and lower BASDAI (P = 0.032) remained as remission predictors. CONCLUSION: This study supports that ASDAS-CRP remission is an achievable goal not only for non-switchers but also for second anti-TNF, particularly in patients with younger age and lower BASDAI at baseline. Co-medication and non-smoker status seems to have a beneficial effect in anti-TNF response in this population.