Objective  To summarize the clinical features of ankylosing spondylitis (AS) complicated with Takayasu's arteritis (TA).

  Methods  We retrospectively analyzed the clinical data of AS complicated with TA patients who had been treated in Peking Union Medical College Hospital from June 2000 to July 2011. AS was diagnosed in accordance with the Modified New York criteria, and TA with American College of Rheumatology classification criteria. All patients had been tested for antinuclear antibody, rheumatoid factor, antineutrophil cytoplasmic antibody, and anticardiolipin antibodies to exclude connective tissue disease and other diseases. Other examinations included tests for erythrocyte sedimentation rate (ESR), C reactive protein, HLA-B27, echocardiography, CT angiography or digital subtraction angiography of aorta and its major branch, color Doppler ultrasound of aorta and its major branch, and X ray and CT of the sacroiliac joint.

  Results  Seven patients4 males and 3 females, with an average age of (29.6±10.6) years (range:18 to 50 years) during this period were diagnosed as AS complicated with TA. HLA-B27 was positive in 5 patients and negative in 2 patients. The levels of inflammatory markers such as ESR and C reactive protein were high in all patients. The average ESR was 84 mm/h. All patients were first diagnosed as AS, then found to be with TA years later. Before the diagnosis of TA, AS had lasted for (13.9±11.6) years (range:3 to 29 years). The main reason leading to the diagnosis of TA was the symptoms of the involved arteries and the fever caused by inflammation.

  Conclusions  AS complicated with TA is not a random phenomenon, in which the inflammatory process may play a crucial role.