A post hoc analysis of a DISCOVER-1 and DISCOVER-2 study subset of PsA patients with investigator-confirmed sacroiliitis (radiograph or magnetic resonance imaging [MRI]) showed significant and robust improvement in axial symptoms of PsA with both guselkumab 100 mg every 4 weeks (Q4W) and every 8 weeks (Q8W) treatment, as assessed by mean changes from baseline in the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and AS Disease Activity Score employing C-reactive protein (CRP) (ASDAS) and by achievement of ≥50% improvement in BASDAI (BASDAI50) and ASDAS responses [18]. Here, CRP is linked to ankylosing spondylitis.