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 (IBP) that might be difficult to distinguish from other causes of chronic back pain (CBP). Many participants report persistent pain, including back pain, which impacts disease activity and quality of life including creating burdens 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 pain control, and the association between pain and clinical/patient-reported outcomes in axSpA participants.

Upadacitinib is being developed for the treatment of axSpA. Approximately 650 adult participants with active-axSpA will be enrolled across approximately 19 countries in Europe, North America, South America, and Asia-Pacific.

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. Participants will be followed for 12 months.

There may be a higher burden for participants in this study compared to usual standard of care. 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.

Inclusion Criteria:

• Clinical diagnosis of Axial Spondylarthritis (axSpA) according to the ASAS criteria.
• Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score >= 4 at Baseline.
• Total back pain score >= 4 at Baseline.
• Inadequate response to at least two nonsteroidal anti-inflammatory drugs (NSAIDs) over an at least 4-week period in total at maximum recommended or tolerated doses, or participant has an intolerance to contraindication for NSAIDs as defined by the investigator.
• Upadacitinib prescribed in accordance with the applicable approved label and local regulatory and reimbursement policies.

Exclusion Criteria:

• Prior exposure to any Janus kinase (JAK) inhibitor.
• Participants demonstrating active symptoms of fibromyalgia as per clinical diagnosis.
• Participation in a clinical trial of an investigational drug, concurrently or within the last 30 days.
• Unwillingness or inability to comply with the study requirements, including completion of patient reported outcome questionnaires.
• Participants who cannot be treated with upadacitinib according to the applicable approved label (e.g., contraindications).
• Vulnerable or protected adult patients with lack of capability to give informed consent.

Adult participants with Radiographic Axial Spondylarthritis (r-axSpA) who have been prescribed upadacitinib in the course of routine practice according to relevant approved licenses.