Axial spondyloarthritis (axSpA) is an immune-mediated inflammatory disease primarily affecting the axial skeleton. The most frequent axSpA symptom is chronic, often inflammatory back pain that might be difficult to distinguish from other causes of chronic back pain. Many participants report persistent pain, including back pain, which impacts disease activity and and impairs quality of life while evoking typical disease burden such as sleep disturbance, social isolation, loss of productivity, as well as anxiety and depression. This study will assess the real-world effectiveness of upadacitinib on early and sustained disease control, and the association between pain and clinical/patient-reported outcomes in axSpA participants. Upadacitinib is being developed for the treatment of axSpA. Approximately 352 adult participants with active axSpA will be enrolled in Germany. Participants will receive oral upadacitinib tablets as prescribed by the physician prior to enrolling in this study in accordance with the terms of the local marketing authorization and professional and reimbursement guidelines with regards to dose, population and indication. The overall duration of the study is approximately 52 weeks. There may be a higher burden for participants in this study compared to usual standard of care due to study procedures. Participants will attend regular visits per routine clinical practice. The effect of the treatment will be checked by medical assessments, checking for side effects, and questionnaires.