Response to: Correspondence on ‘No efficacy of anti-IL-23 therapy for axial spondyloarthritis in randomised controlled trials but in post-hoc analyses of psoriatic arthritis-related ‘physicianreported spondylitis’?’ by Siebert and Marzo-Ortega

With great interest, we read the comment of our colleagues from the UK on our recent viewpoint,1 and we appreciate that they largely agree with us.2 This is a bit different in a recent review on the same topic,3 which argues that it is still possible that anti-IL23 agents work for axial psoriatic arthritis (PsA). Nevertheless, our colleagues from the UK raise two important points, which we like to shortly comment on. First, the important factor of age is discussed, which plays an important role in the frequent clinical situation of patients presenting to the doctor because of acute or chronic back pain—simply because the prevalence of degenerative changes in the axial skeleton does increase with age,4 5 and axial spondyloarthritis (axSpA) starts most often in the third decade of life6 …