Disease Activity Cutoff Values in Initiating Tumor Necrosis Factor Inhibitor Therapy in Ankylosing Spondylitis: A German GO-NICE Study Subanalysis

Objective. International recommendations for the management of axial spondyloarthritis including ankylosing spondylitis (AS) recommend a Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) level of disease activity of >= 4 to initiate treatment with biologics. We aimed to evaluate the level of disease activity used to initiate tumor necrosis factor inhibitor (TNFi) treatment and the level of responses to treatment based on different BASDAI cutoffs. Methods. This is a posthoc analysis of the noninterventional, prospective, GO-NICE study in the subgroup of biologic-naive AS treated with golimumab (GOL) 50 mg subcutaneously once monthly. Results. Of the 244 biologic-naive AS patients at baseline, 70.5% had a BASDAI >= 4 (Group 1), 14.3% had 2.8 to < 4 (Group 2), and 15.2% had even < 2.8 (Group 3). A total of 134 patients (54.9%) completed the 24-month observational period. The mean BASDAI in Groups 1, 2, and 3 was initially 5.9 +/- 1.3, 3.4 +/- 0.4, and 2.0 +/- 0.8, decreased to 2.2 +/- 2.0, 1.9 +/- 1.2, and 1.0 +/- 1.2 within 3 months (all p < 0.0001 vs baseline), and decreased significantly to 2.2 +/- 1.7, 1.9 +/- 1.7, and 1.4 +/- 1.0 at Month 24 (all p < 0.005), respectively. BASDAI 50% improvement was noted in 68.8%, 44.8%, and 45.2% of patients at Month 3, and in 84.9%, 61.9%, and 55.0% at Month 24. Conclusion. TNFi treatment was initiated in almost a third of AS patients with lower disease activity states as assessed by BASDAI cutoff of >= 4. Patients with a BASDAI between 2.8 and < 4 appeared to benefit significantly from GOL treatment, while patients with BASDAI < 2.8 did not. This finding should lead to a reevaluation of the established BASDAI cutoff of >= 4.