Ankylosing Spondylitis

• Non-governmental Healthcare Institution "Railway Clinical hospital on the Chelyabinsk Station of JSC Russian Railways" — Chelyabinsk, Russia
• Chelyabinsk Regional Clinical hospital — Chelyabinsk, Russia
• Kazan State Medical University — Kazan', Russia
• State Budgetary Higher Vocational Education Institution I.M. Sechenov First Moscow State Medical University — Moscow, Russia

Not specified

• Kocaeli University — Kocaeli, Turkey (Türkiye)

• Izmir University of Economics — Izmir, İzmir, Turkey (Türkiye)

• It is an observational study based on the The Swedish Rheumatology Quality Register — Stockholm, Sweden

• Orthopedic Outpatient Room — Fuzhou, China

• Bakırkoy Dr Sadı Konuk Hospıtal — Istanbul, Bakirkoy, Turkey (Türkiye)

• Afyonkarahisar Health Sciences University — Afyonkarahisar, Turkey (Türkiye)

• Teaching Hospital of Royal Vineguards — Prague, Czechia

• As0009 30 — Sarasota, Florida, United States
• AS0009 1 — Duncansville, Pennsylvania, United States
• AS0009 6 — Dallas, Texas, United States
• As0009 156 — Dobrich, Bulgaria