Osteoporosis in Hong Kong : important issues in prevention, assessment and treatment

The overall objective of the present study is to find out effective measures to prevent fractures among postmenopausal women in the Hong Kong population. Fracture prevention can be accomplished by preventing bone loss within the general community, especially over menopausal transition, and identifying high risk subjects for treatment. There is relative paucity of data regarding bone loss across menopausal transition among Chinese women. 160 women between 45 to 55 years old were followed up longitudinally for four years for bone mineral density measurement. Data on menstrual status, lifestyle and dietary habits were collected. Biochemical and hormonal assay were carried out. The time of onset, rate and determinants of peri-menopausal bone loss were investigated. No significant bone loss was detected at both spine and hip in premenopausal women. Maximal bone loss was noted at the peri-menopausal stage (STRAW stage -1/-2) and bone loss attenuated after final menopausal period. Subjects tended to experience more rapid bone loss if they were older, had an early menopause, weighed less or had a higher FSH level at baseline. The second part of the study aimed to investigate means by which to identify high risk postmenopausal women for treatment to prevent fracture. This part consisted of three studies utilizing the same cohort of 2266 local postmenopausal Chinese women. First, the discriminative values of various models for fracture prediction were compared. Second, the clinical utility in fracture prevention was evaluated when different international guidelines were applied to this cohort. Third, the effectiveness in fracture prevention using different intervention strategies was assessed. The discriminative value for major osteoporotic fracture prediction was found in our study to be better for an ethnic specific clinical risk factors model with T-score than the WHO Fracture Risk Assessment (FRAX) while the performance for hip fracture was similar. The former model has a 10% higher sensitivity than FRAX at specificity of 0.8 or above. The clinical utility of various international guidelines including NOF, National Osteoporosis Guideline Group (NOGG) and Taiwanese guidelines to direct BMD screening and treatment strategies for fracture prevention was compared and found to be low as reflected by the poor clinical utility index. Finally, different treatment strategies which include treating women with prior fractures, women with age-specific FRAX probability corresponding to those with prior fractures, women with osteoporosis as well as women with FRAX probability above a fixed cut-off based on optimizing sensitivity and specificity on the ROC curve were compared. All strategies had negative predictive value of >90%. Using a fixed cut-off of 9.95% (major osteoporotic fractures, with BMD, determined by finding the optimal threshold point from the ROC curve) had the highest sensitivity but lowest specificity and positive predictive value. The above findings may help to design effective public health measures to prevent osteoporosis and provide an important step in the development of treatment guidelines specific to the Hong Kong population.published_or_final_versionMedicineMasterDoctor of Medicin