Non-Steroidal Anti-inflammatory Drugs in Axial Spondyloarthritis

Patients with ankylosing spondylitis or axial spondyloarthritis who fulfills the inclusion
and exclusion criteria will be randomized into one of the four arms after an initial one week
washout period, including: 1) indomethacin 75mg Q12H; 2) diclofenac 75mg Q12H; 3) meloxicam
7.5mg Q12H; 4) celecoxib 200mg Q12H. The treatment length will be 6 weeks. Primary outcome is
the change of pain score from baseline to week 4 and to week 6.

Inclusion Criteria:

- A clinical diagnosis of ankylosing spondylitis (AS) by treating rheumatologists, or a
diagnosis of axial spondyloarthritis (axSpA) with a pelvis MRI with significant bone
marrow edema on STIR sequences;

- Minimum of 18 years old;

- Are taking NSAIDs on a regular basis for AS or axSpA (defined as more than 20 days in
the past month) and willing to withhold medication for one week; or having active
symptoms that require initiation of NSAIDs;

- Concomitant anti-rheumatic drugs are allowed, if the dose has been stable for the past
three months;

- Have active disease after initial washout period, defined by BASDAI >=4/10, or back
pain numerical rating scale (NRS)>=4/10

Exclusion Criteria:

- Patients who have concurrent rheumatic diseases other than AS or axSpA;

- Patients who have oral corticosteroid in the past two weeks; patients who have acute
peripheral arthritis;

- Patients with a fibromyalgia score >= 13;

- Patient with extensive cardiac history, history of gastrointestinal bleeding that
required blood transfusion, chronic kidney diseases, abnormal liver function tests; or
female patients who are pregnant.

Use of low-dose of aspirin (<100mg daily) is allowed in the study.