A possible confounding factor that may increase the number of axSpA patients with psoriasis undergoing bDMARDs is the tumour necrosis factor-α (TNF-α) inhibitor-induced psoriasis phenomenon.37 In the DESIR cohort, 33 patients (4.7% of all patients and 18.3% of patients with psoriasis) were diagnosed with psoriasis after being treated with a TNF alpha inhibitor, though causality was not established. Here, TNF is linked to psoriasis.