RecruitingRemibrutinib in Real-world Clinical Practice - a US Sub-studyProspective, non-interventional study in patients with CSU where the treatment decision prior enrolment has been made to either escalate current sgH1-AHs treatment or escalate/switch current treatment to remibrutinib. The primary aim of this study is to gather real-world effectiveness and safety data for remibrutinib, a new treatment option, covering a broader, real-world clinical practice population.