Effects of Nonsteroidal Anti-Inflammatory Drugs in Recurrence of Spondyloarthritis Patients After Remission

Inclusion Criteria:

1. Capable of giving informed consent and complying with the examination program of the protocol;
2. Participants with axial SpA fulfilling the Assessment of Spondyloarthritis international Society 2009 (ASAS) axial SpA classification criteria;
3. Participants must fulfill the criteria of maintaining remission of aSpA, defined as ASDAS<1.3；
4. Participants must fulfill the criteria of remission of aSpA defined as ASDAS<1.3，then continuous to evaluate every four weeks for three times and ASDAS<1.3 each time.
5. Laboratory results must fulfill following requirements: Hb≥85g/L；3.5×109/L≤WBC Count ≤10×109/L；Platelet count ≥ Normal lower limit; Liver function (ALT、TBIL) ≤Twofold of normal upper limit; Renal function (SCr) ≤Normal upper limit;
6. The pregnancy test must be negative for women of childbearing age; Efficient contraception must be taken for both male and female participants during the trial period and within three months after the end of the trial.

Exclusion Criteria:

1. Participants who previously have experienced allergic reactions to NSAIDs or sulfa-drugs;
2. Participants who are intolerant of NSAIDs;
3. Participants who are in active axSpA episodes;
4. Participants with previous or currant ulcers and/or gastrointestinal conditions or bleeding in three months
5. Participants who were in acute infection or acute attack of chronic infection during screening period;
6. At the time of screening, participants who were in the acute stage of acute infection or chronic infection, and if the acute infection had improved, they could be re-screened.
7. Participants who suffer from invasive fungal infections (e.g. histoplasma, coccidiosis's, candida, aspergillus, blastomyces, pneumocystis, etc.) within the first 6 months of screening; Or opportunistic bacterial infections (e.g. bacterial, viral or other infections, including Legionella and Listeria);
8. Participants with other autoimmune diseases which are expected to influence the evaluation of experimental medications, such as inflammatory enteritis, psoriasis, uveitis, etc.
9. Participants with previous or currant congestive heart failure, coronary heart disease, serious arrhythmia;
10. Participants with severe, progressive, uncontrolled vital organ and systematic disorders, and other conditions that are considered inappropriate to participate in this trial;
11. Participants with circumstances that may affect the compliance (e.g. prolonged travel or leave, planned relocation, mental illness, lack of motivation to participate, etc.).