This is an observational study to evaluate the effectiveness and safety of secukinumab in participants with AS who have never used TNFi, JAKi, or IL-17i drugs before.

This study is an observational study to evaluate the effectiveness and safety of secukinumab in patients with ankylosing spondylitis who are naive to TNFi/JAKi/IL-17i in Korea. Subjects will be recruited from 10 institutions in Korea. The enrollment period is 8 months from the initiation at the first institution and the follow-up periods are 28 weeks(±4 weeks). Data will be gathered at initial visit, 16 weeks(±4 weeks), and 28 weeks(±4 weeks).

Secukinumab is prescribed within the scope of labeling approved in Korea.

Inclusion Criteria:

1. Subjects diagnosed with ankylosing spondylitis (AS), as defined by the modified 1984 New York criteria
2. Subjects who have symptoms of active disease at screening and baseline, as evidenced by BASDAI score of ≥ 4
3. Subjects who have never used TNFi, JAKi, or IL-17i drugs before
4. Patients suitable for secukinumab treatment within the scope of labeling by the Ministry of Food and Drug Safety
5. Subjects who have a time of less than 5 years since AS diagnosis
6. Subjects who are above the age of 18 years and below 40years old
7. Subjects who give informed consent form to participate in the study

Exclusion Criteria:

1. Subjects who are in a medical or psychological condition which may prevent them from participating in the study for the study period(28±4 weeks)
2. Subjects who have congenital/traumatic spinal deformities
3. Subjects currently enrolled in other clinical studies
4. Subjects who have any contraindications to secukinumab treatment

The subjects are biologic-naive AS patients who are <40 years old and have a time of less than 5 years since AS diagnosis.