[Diagnosis and treatment of rheumatoid arthritis:toward the best practice. Best practice with JAK inhibitors.].

Janus kinase(JAK)inhibitor is a new orally available disease modifying anti-rheumatic drug that has shown anti-rheumatic effect resembling biologics. Clinical trials for autoinflammatory and autoimmune diseases are under investigation. Administration route is convenient compared to biologics and possess high anti-rheumatic effect, however specific side effects considered as a class-effect exists. I would like to offer the best conceivable practice with JAK inhibitors based on evidence from clinical trials and real world experiences.