[Standardized diagnosis and treatment of undifferentiated connective tissue disease and mixed connective tissue disease].

ribonuclear protein (RNP) antibody in serum, while with negative anti-Sm antibody. The update of diagnosis and treatment of undifferentiated CTD and mixed CTD lags behind other established CTD. There is a lack of evidence from randomized controlled trials or guidelines/recommendations on the treatment of undifferentiated CTD or mixed CTD. At present, the conventional therapy is mainly adopted according to the specific clinical manifestations of the disease. The standardized diagnosis and treatment of undifferentiated CTD and mixed CTD were drafted by the Chinese Rheumatology Association based on the previous guidelines and the progress of available evidence, so as to improve the management of these patients in China.