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

Undifferentiated connective tissue disease (CTD) usually refers to patients who are presented with certain symptoms and signs related to CTD, and positive serological evidence of autoimmune diseases but don't fulfill any of the classification criteria for a certain CTD. Mixed CTD refers to patients who are presented with one or more clinical manifestations such as hand swelling, synovitis, myositis, Raynaud's phenomenon, and acrosclerosis. Patients with mixed CTD always have high-titer anti-nuclear antibodies (ANA) of speckled pattern and high-titer anti-U1 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.未分化结缔组织病（CTD）通常指患者出现某些CTD相关的症状和体征，同时伴自身免疫病的血清学证据，但不符合任意一确定的CTD分类标准。混合性CTD是指患者出现手肿胀、滑膜炎、肌炎、雷诺现象、肢端硬化等一种或多种临床表现，伴血清高滴度斑点型抗核抗体（ANA）和高滴度抗U1核糖核蛋白（U1RNP）抗体阳性，而抗Sm抗体阴性。未分化CTD和混合性CTD的规范化诊断和治疗的更新慢于其他确定的CTD，治疗均缺乏随机对照研究证据或指南推荐，目前主要按照构成疾病的具体临床表现而采用相应的常规治疗措施。中华医学会风湿病学分会在既往诊治指南及近年研究进展的基础上制定了本规范，旨在提高国内未分化CTD和混合性CTD的临床诊治水平，改善患者预后。.