a 5-year follow-up study investigating factors associated with osteoporotic fracture in chinese postmenopausal women

Conditions: Osteoporotic Fractures; Osteoporosis, Postmenopausal

Summary: this proposed study was designed to investigate the prevalence of a 5-year incident osteoporotic fracture and evaluate the association of a 5-year change of 25-hydroxyvitamin d (25\[oh\]d)/bone turnover makers/bone mineral density (bmd) with the incident fracture in the chinese postmenopausal women, based on an endeavor of a 5-year post-baseline follow-up visit of a previous cross-sectional study, pk-vf, in which 1724 participants were enrolled and examined.

1. in 2013, 5 years after pk-vf, the same 2070 subjects were contacted by the original sites. among them 1242 subjects were able to come for the follow-up assessment. 2. clinical assessments: the participant's bio-information, physical examination and medical history were collected;questionnaire including social/life style and medical evaluations (years since menopause (ysm), fracture history, milk/yoghourt/coffee/wine intake, calcium intake, or smoking history) were collected by pk-vf investigators. non-vertebral fracture history evaluation: specific non-vertebral fracture sites include rib or clavicle, forearm, upper arm, hand (including wrist), pelvis, hip, thigh (not including hip), leg, and foot (including ankle). when non-vertebral fractures are suspected, questions were raised to the participant to eliminate possible biases (how did you get these fractures, a slight fall at home, fell from a high place, hit by someone, broken during a car accident or an operation? did you see a doctor to confirm these fractures?) a fracture occurred in regular daily activities or due to mild trauma was defined as fragile non-vertebral fracture. 3. biochemical measurements: fasting blood sample (\~5 ml) was collected from each participant at participating sites; in 2007-2008 study, blood samples were collected during april-july, while in the 5-year follow-up; samples were collected in the same period of time. c-terminal telopeptide of type i collagen (β-ctx), n-aminoterminal prepeptide of type i procollagen (p1np), and 25 (oh) d will be determined by a laboratory method of electrochemiluminescence (e170; roche diagnostics, basel, switzerland) in the institute (peking union); chemistry including alkaline phosphatase (alp), calcium (ca), creatinine (cr), and glucose, will be measured by using automated techniques in the institute (peking union); 4. bmd measurements: lumbar spine (ls) and femoral neck (fn) bmds by dual-energy x-ray absorptiometry (dxa) (lunar or norland) at pk-vf sites. bmd calibration: the participant's bmd were evaluated by the same type of dxa as previous. the coefficients of variation of the seven hospitals were 0.75% to 1.7% for ls and 0.56% to 1.0% for fn. cross-calibration equations between machines are: ls bmd (g/cm\^2) lunar = 1.012 × norland + 0.0137 and, fn bmd (g/cm\^2) lunar = 1.0377 × norland + 0.00026 5. vertebral fracture diagnosis: lateral radiographs of the thoracolumbar spine (t4-l5) were taken at pk-vf sites. vertebral fractures will be assessed using genant's semi-quantitative visual criteria. two specialist radiologists will independently evaluate and diagnose vertebral fracture. a worsened existing vertebral fracture will be regarded as a new vertebral fracture. in 2007-2008 study(published article about this study could be found in pubmed, pmid: 24760246), 2070 participants were recruited in this cohort, and 837 subjects (40%) were diagnosed as osteoporosis. after 5 years, 1242 subjects agreed to be re-evaluated in 2013. questionnaires and blood samples were collected, and bmd and spine x-ray were obtained at the 5-year follow up. we estimate that around 625 subjects would be diagnosed as osteoporosis. the remaining works include blood sample test (25(oh)d, ctx and p1np),spine x-ray films reading, data input and statistical analysis, paper writing and publication.

Eligibility criteria:
inclusion criteria: 1. postmenopausal women (normally over 50 years old and years since menopause over than 1 year) in peking. 2. participants without any fracture in 2007 pk-vf study were included in the prospective study investigating the association of bone turnover markers/bmd/25(oh)d with fracture incidence. exclusion criteria: participants with years since menopause less than 1 year.

Keywords: bone mineral density 25(oh)d