Analysis of bone mineral density in 1051 patients with ankylosing spondylitis

Objective To study the incidence of osteopenia and osteoporosis in 1051 patients with ankylosing spondylitis(AS),to investigate the effect of gender,age,duration of disease,HLA-B27,and the activity of disease on the genesis of osteoporosis associated with AS,and to explore the mechanism of osteoporosis in patients with AS.Methods Bone mineral density(BMD) of the lumbar vertebrae,the femoral neck,and the femoral trochanter of 1051 patients with AS and 767 subjects in healthy control group was measured using DEXA.Levels of erythrocyte sedimentation rate(ESR),C-reactive protein(CRP),PGA,rachialgia,and BASDAI was measured in AS group.Results The total incidence of osteoporosis and osteopenia in 1051 AS patients was 34% and 33.78%,respectively.The incidence of osteoporosis and osteopenia in the lumbar vertebrae and the femoral neck was 26.83% and 24%,7.33% and 21.03%,respectively.BMD of the lumbar vertebrae of the patients in AS lower-age group(20-29 years) was significantly lower than that in middle-age group(30-39 years) and the elder group(40-45 years).BMD of the femoral neck in AS lower age group was significantly lower than that in middle age group.The incidence of osteoporosis in male and female AS patients was 39.32% and 11.06%,respectively.BMD of the lumbar vertebrae,the femoral neck,and the femoral trochanter in HLA-B27 positive patients was significantly lower than that in HLA-B27 negative patients.BMD of AS patients in early stage with no decline of spinal function was significantly lower than that in control group(P0.001).BMD of patients with AS was significantly negatively correlated with the extent of sacroiliitis,ESR,and CRP.Conclusion The incidence of osteoporosis in AS patients is high.Patients in young,middle-aged stage,early onset,and middle term have showed a reduction of BMD of the lumbar vertebrae and the femur.The incidence of osteoporosis in male AS patients is higher than that in female AS patients.The incidence of osteoporosis in HLA-B27 positive patients is higher than that in HLA-B27 negative patients.Disuse is not the main reason of osteoporosis in AS patients,but it may aggravate the extent of osteoporosis in AS patients.The occurrence of osteoporosis in AS patients is correlated with the inflammatory activity of the disease and the extent of sacroiliitis.