A Study Of Vertebral Fracture In Peking And The Association Between Bone Turnover Markers And BMD And Vertebral Fracture

BackgroundOsteoporosis has been gradually becoming a public healthy problem in China and also around the world along with the aging of the population. Osteoporotic fracture(OF) is one of the severe complications of osteoporosis, which causes a relative high rate of disability and even death. OF impacts the life quality of patients severely and brings the society heavy economic burden. Vertebral fracture(VF) is the most common form of OF. However, since VF is usually without a history of injury and the symptoms of VF are somehow insidious, patients of VF often can not notice. This causes the poverty of epidemiological data of VF. The study of the risk factors of VF is an important way to prevent VF, however prospective study in large-scale population concerning risk factors of VF is now deficient. The detection of bone turnover markers(BTM) is a convenient and non-invasive way to assess the situation of bone remodeling. Thus BTM has potential value in the assessment of osteoporosis, prediction of bone loss rate, evaluation of OF risk, and monitoring of the effectiveness of anti-osteoporotic drug therapy.Objective1. Calculating the prevlance of VF of postmenopausal women aged above 50 years old in Peking. Comparing the data with that of the first PK-VF epidemiological survey in 2008.2. Calculation the incidence of new VF from 2008 to 2013 in the follow-up population.3. Analyzing the association of clinical risk factors and new VF through Logistic regession model.4. Analzing the characteristic of the BTM of postmenopausal women, and the relationship between BTM and bone loss rate and new VF.Subjects and methods1. Subjects:two research cohorts are included in this study. The first cohort is 1991 postmenopausal women participated in the second PK-VF survey in 2013. The second cohort is 876 postmenopausal women participated in the 2008-2013 follow-up survey.2. Methods:1) Questionaire survey:we use the same questionnaire of 2008 to collect clinical data of the subjects. The questionnaire includes basic data, menstruation and pregnancy, habits and customs, daily activity, common healthy situation, history of drugs and history of factures.2) Biochemical markers analysis:Fasting blood sample was collected for each subject. Common biochemical maerkers including serum calcium(Ca), serum phosphate(P), serum glucose(Glu), serum creatinine(Cr), alkaline phosphatase(ALP), alanine aminotransferase(ALT) were analyzed. Besides, we also detect bone speficific markers including 25-hydroxyl Vitamin D(25OHD), parathyroid hormone(PTH), β-isomerized C-terminal telopeptide of type Ⅰ collagen(β-CTX), N-terminal procollagen of type 1 collagen(P1NP) and osteocalcin(OC).3) Bone mineral density(BMD) examing:we use dual energy X-ray absorptiometry (DXA) to exam the BMD at lumbar spine (L2-4, LS) and hip.4) Vertebral fracture assessment:X-ray of thoracic and lumbar spine was taken, and the pictures were read by radiological specialists. The diagnosis of vertebral fracture was executed according to Genant’s semiquantitative technique. 5) Statistical analyses were performed by SPSS 22.0 for windows.Results1. In all the 1991 subjects in corhort 1, the prevlance of vertebral fracture is 21.8%(95%CI 19.9-23.7%). This data is comparable with the prevlance in 2008, which is 24.0% (22.0-26.0%). The prevlance of vertebral fracture increases with age, and the most common site is T11-L1 vertebrae.2. In the follow-up population, cohort 2, the annualized incidence of new vertebral fracture is 1030/100,000 person-year.3. The decrease of LS BMD and a history of previous vertebral fracture are indepent risk factor of new vertebral fracture.4. The level of BTM, especially β-CTX is significantly inversely correlated with BMD. The baseline level of BTM measured in 2008 is not significantly correlated with bone loss rate during 2008-2013. However, the bone loss rate of subjects with constantly high β-CTX level in both two measurements of 2008 and 2013 is 51% faster than those with constantly low β-CTX level.ConclusionThe prevlance of vertebral fracture of the postmenopausal women aged above 50 in Peking remains stable from 2008 to 2013. The annualized incidence of new vertebral fracture is 1030/100,000 person-year, which is close to the data of Caucasian. Among the numerous clinical risk factors, only the decrease of LS BMD and a history of previous vertebral fracture are indepent risk factors of new vertebral fracture. No significant association has been found between BTM and new vertebral fracture. Single evaluation of BTM level seems to be useless in predicting the future bone loss rate. However subjects with constant high β-CTX level through repeated measuring may be at higher risk of rapid bone loss.