Rheumatoid arthritis classification criteria: 1. Morning stiffness: stiffness in and around joints lasting at least 1h (duration of disease >= 6 weeks). 2.Arthritis in 3 or more regional joint sites: 3 of 14 regions (left or right proximal interphalangeal joint, metacarpophalangeal joint, wrist, elbow, knee, ankle and metatarsophalangeal joint) were observed by the physician to be involved and were accompanied by soft tissue swelling or fluid accumulation (not just bone augmentation) (duration of disease >= 6 weeks). 3.Hand arthritis: at least one joint swelling in wrist, metacarpophalangeal or proximal interphalangeal arthritis (duration of disease >= 6 weeks). 4.Symmetric arthritis: both joints are involved at the same time (bilateral proximal interphalangeal joints, metacarpophalangeal joints and metatarsophalangeal joints may not be absolutely symmetrical when they are involved) (duration of disease >= 6 weeks). 5.Rheumatoid nodules: The doctor observed subcutaneous nodules on the bony prominence, extensor surface or around the joint. 6, positive rheumatoid factor: any test that demonstrates abnormal serum rheumatoid factor levels, and the method has a positive rate of less than 5% in the normal population 7, radiological changes: typical radiological changes of rheumatoid arthritis in the posterior-anterior phase of the hand and wrist: must include bone erosion or definite bone decalcification in the affected joint and its adjacent areas. RA can be diagnosed by meeting four or more of the above seven criteria and excluding other arthritis.