An epidemiological survey of low back pain and axial spondyloarthritis in a Chinese Han population

OBJECTIVE: To investigate the prevalence of low back pain (LBP) and axial spondyloarthritis (SpA) in a Chinese Han population. METHODS: A face-to-face investigation was performed in the Han population of Dalang Town, Yangshan County, Guangdong Province, China, using a questionnaire established in France in 1999. First the clinical features associated with SpA were investigated, then the human leucocyte antigen (HLA)-B27 and sacroiliac joint radiographic examinations were carried out. Finally, the diagnosis of SpA was determined by rheumatologists. RESULTS: A total of 13 315 subjects participated in the study and 10 921 were aged >16 years; of these, 787 (7.21%) had LBP. There were 92 axial SpA patients (0.782% in subjects >16 years old and 11.96% in subjects with LBP). There were 29 (0.253%) cases of ankylosing spondylitis (AS), 60 (0.507%) undifferentiated axial SpA (USpA), and three (0.022%) psoriatic arthritis (PsA). Patients in the SpA groups had higher percentages in onset <40 years, insidious onset, morning stiffness, and affected for >3 months compared with those in other LBP groups. Simultaneous symptoms associated with spondylitis, such as buttock pain, heel pain, psoriasis, and SpA family history, were more commonly present. Of the axial SpA patients, 82.67% were HLA-B27 positive, clearly a greater percentage than those (11.65%) in other LBP groups. CONCLUSIONS: The survey questionnaire for SpA in this study is useful for axial SpA screening in China. In southern China, the prevalence of LBP is 7.21%. The prevalence of axial SpA is 0.782%. USpA is the most common subtype of SpA, followed by AS.