Ankylosing Spondylitis (AS) is a chronic inflammatory disease. It mainly invades sacroiliac joint, spine process, paravertebral soft tissue and peripheral joints, causing symptoms such as inflammatory pain, morning stiffness, movement limitation. In severe cases, ankylosing spondylitis may occur. At present, the number of ankylosing spondylitis patients in China is between 5 million and 10 million, and the number of people affected is growing at the rate of hundreds of thousands per year. 

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by synovitis. It mainly manifests as symmetrical, chronic and progressive polyarthritis. As the disease progresses, it may cause destruction of articular cartilage, bone and joint capsule, and eventually lead to joint deformity and loss of function. RA is one of the main causes of labor loss and disability in China. At present, there is no way to cure it, you can only control the condition.  

China has done an epidemiological survey. According to the result of the survey, the prevalence rate of RA is 0.36%. If calculation is done based on the idea that the population is 1.3 billion, we should expect around 5 million RA patients in China. Thereof, 70% RA patients are moderate to severe. The first-line treatment is mainly consisted of methotrexate-based anti-rheumatic drugs (DMARD), which is used to alleviate symptoms such as inflammation. However, some patients have hyporesponsiveness or intolerant reaction to DMARDs, thus making biological agents and JAK targeting drugs the new choices. 

Psoriatic arthritis (PsA) is an inflammatory arthropathy associated with psoriasis. The patient has psoriatic rashes, accompanied with pain, swelling, tenderness, stiffness and movement disorders of the joints and surrounding soft tissues. Psoriatic arthritis occurs in 10-30% psoriasis patients.