This study is a population-based cohort of patients with ankylosing spondylitis (AS) from general medical practices in the UK, France, and Germany with a nested case control component to assess associations between drug exposures of interest and clinical outcomes relevant to patients using cyclooxygenase-2 (COX-2) inhibitors / nonsteroidal anti-inflammatory drugs (NSAIDS).

The main objective of the study is to describe in European participants with AS: 1) the use of etoricoxib 2) characteristics of those who use etoricoxib. 3) the safety profile of etoricoxib and other anti-inflammatory therapies with respect to specific clinical outcomes of interest relative to non-use of these medications and relative to each other.

Inclusion Criteria:

• A recorded Ankylosing Spondylitis diagnosis in the database
• A recorded AS diagnosis following the applicable "acceptable data quality" date for the database that contains the patient's records
• At least 6 months of registered medical records in the database after the applicable "acceptable data quality" date as described above, and prior to the recorded AS diagnosis
• Complete information on gender and birth year

This study will use the combination of the General Practice Research Database (GPRD) in the UK, The Health Improvement Network (THIN) database in the UK, and the IMS Disease Analyzer Database (Disease Analyzer) in the UK, France and Germany.