| Objective: The objective of this study, in which the correlation analyses among two BMD datasets and other clinical indicators were conducted in parallel, is to explore the characteristics of BMD in HLA-B27 positive and negative ankylosing spondylitis (AS) patients. Methods Patients diagnosed with AS in China-Japan Friendship Hospital from March 2006 to December 2014, including 652 HLA-B27 positive patients and 99 HLA-B27 negative patients, were retrospectively surveyed. BMD of the lumbar spine, femoral neck, and trochanter were measured by dual energy X-ray absorptiometry. Correlation analyses with age, disease duration, disease activity index, radiological indicators and other clinical signs were performed. Results ①BMD of lumbar spine, femoral neck, and trochanter in HLA-B27 positive AS patients were significantly lower than that in the negative patients (P<0.01). The total incidence of OP and OT in HLA-B27 positive AS patients (66.76%) was significantly higher than that of the negative patients (41.41%). The incidence of OP at lumbar spine and OT at femoral neck and trochanter in HLA-B27 positive AS patients were significantly higher than that of the negative patients (P＜0.01, 0.01, 0.05). ②In the younger age group (20-29years old), BMD of the lumbar spine and femoral neck were lower in HLA-B27 positive AS patients than in the negative patients. In the older-age group (40-45years old), BMD of the lumbar spine were significantly lower in HLA-B27 positive AS patients than in the negative group. In patients who had AS for 5 years or less, BMD of the lumbar spine were lower in HLA-B27 positive AS patients than in the negative patients. In patients who had AS for 5 to 10 years, the total BMD was significantly lower in HLA-B27 positive AS patients than in the negative group（P<0.05, 0.01, 0.05, 0.01). ③ The total BMD in HLA-B27 positive AS patients was closely related with age and clinical signs (P<0.01). Conclusion The incidence of OP and OT was higher in the HLA-B27 positive AS patients, especially at lumbar spine, which showed obvious decrease of BMD. HLA-B27 positive AS patients showed a reduction of BMD at young-age, early onset and middle term, which could lead to function decline of the body. HLA-B27 positive AS patients should pay more attention to the screening, prevention and treatment of OP and OT, especially the examination of lumbar spine BMD. |