[The value of researches, which assess bone mineral density and bone metabolism in patients with ankylosing spondylitis, in detecting osteoporosis].

BACKGROUND

Purpose of the study was: 1) to assess the best localization and the method for diagnosis of osteoporosis; 2) to assess risk factors of osteoporosis; 3) to assess risk factors of spinal fractures due to osteoporosis; 4) assessment of bone metabolism.

METHODS

The study consisted of 46 male patients with confirmed diagnosis of ankylosisng spondylitis (AS) aged 23-68 years. All patients underwent the following assessment: lateral x-ray of spine, bone mineral density (BMD) assessment of lumbar spine, femoral neck and radius by DEXA method and bone mineral density assessment of radius by peripheral quantitative computed tomography (pQCT) method. Activity of bone specific alkaline phosphatase, hydroxyproline-creatinine ratio and calcium-creatinine ratio were assessed. The following indexes were assessed: BASMI, BASFI, BASDAI, BASG-t i BASG-6. Biochemical activity of the disease was assessed by C-reactive protein (CRP), mucoproteids, fibrinogen, erythrocyte sedimentation rate.

RESULTS

34.8% of AS patients had spinal fractures. There were 19 fractures of thoracic spine, 9 of cervical and 5 of lumbar spine. There was negative correlation of spinal fractures and neck osteopenia (r = -0.485; p = 0.05). There was increased relative risk of fractures in patients with increased BASFI, BASDAI and BASMI and with increased level of CRP. Older patients with longer history of disease had higher relative risk of fractures. Together along with the duration of disease there was the decrease of neck BMD and the increase of lumbar BMD. AS patients compared with control group had increased hydroxyproline-creatinine ratio.

CONCLUSIONS

Ankylosing spondylitis patients have increased risk of spinal fractures due to osteoporosis. Assessment of BMD at femoral neck is the best for assessment of osteoporosis in AS patients.