Background/Purpose: There is a need to better characterize patients with ankylosing spondylitis (AS) who discontinue vs continue TNF inhibitor (TNFi) therapies in real-world clinical settings. The objective of this study was to compare patient characteristics and disease outcomes in patients with AS who continued vs discontinued a TNFi therapy by their second follow-up visit in the US-based Corrona Psoriatic Arthritis/Spondyloarthritis (PsA/SpA) Registry.

Methods: All patients with AS aged ≥ 18 years enrolled in the Corrona PsA/SpA Registry between April 2013 and January 2015 who were receiving or initiated a TNFi agent at the time of registry enrollment (index visit) and had ≥ 2 follow-up visits were included. Patients were assigned to a cohort based on continued or discontinued use of their TNFi at the second follow-up visit (mean [SD] follow-up, 17.8 [7.1] months). Patient demographics, clinical characteristics, patient-reported outcomes (PROs) and treatment history at baseline were compared between cohorts using t-tests for continuous variables and chi-square or Fisher’s exact tests for categorical variables. Reasons for discontinuation of the index TNFi were summarized descriptively. Mean changes from baseline in clinical disease activity measures and PROs were assessed at second follow-up and compared between cohorts using unadjusted mean differences.

Results: Of the 155 included patients, 37 (23.9%) discontinued their index TNFi therapy by the second follow-up visit, including 24 patients who switched to another biologic. Patients who discontinued their index TNFi were significantly older (52.1 vs 46.6 years), more likely to be obese (59.5% vs 34.2%) and had significantly worse mean BASDAI (4.8 vs 3.5) and BASFI (4.2 vs 2.8) scores at the index visit compared with those who continued their TNFi. Of the 37 patients who discontinued their index TNFi, 18 provided reasons for discontinuation; the most common provider-reported reasons for discontinuation were lack of effect (n = 6), side effects (n = 4) and other reasons (n = 5). Patients who discontinued their index TNFi had worse outcomes with respect to disease activity and PROs at the second follow-up visit compared with those who continued their TNFi; however, differences between the groups did not reach statistical significance (Table 1).

Conclusion: Patients with AS in the Corrona PsA/SpA Registry who discontinued their index TNFi therapy by the second follow-up visit were older, more likely to be obese and had higher disease activity at baseline compared with patients who continued their TNFi. Differences in clinical disease activity measures and PROs at the second follow-up visit between those who discontinued vs continued their TNFi did not reach statistical significance, possibly due to small sample size. These results provide insight into patient characteristics and disease outcomes in patients with AS who discontinue vs continue TNFi therapy.