| Objective To understand the geographic differences of bone mineral density (BMD) in women and the effect of using a multi-center combined reference database for diagnosing osteoporosis. Methods The reference population comprised 10343 females, aged 20–89 years old, from Changsha, Beijing, Nanjing, Shanghai, Jiaxing, Guangzhou, and Chengdu. Except for Changsha (n=1157), data were obtained from the GE Health Care service. Lumbar spine and femoral neck BMD was measured in the subjects using a bone densitometer (GE-Lunar DXA series). Results Data were analyzed using eight different regression models. We found that the cubic regression model was the best for describing age-related changes in BMD. The coefficients of determination (R2) of the fitting curve were 0.149 to 0.546 (all P=0.000). For the best-fit curve of lumbar spine BMD with age, the minimal difference was between Beijing and Nanjing (3.0± 3.4%), and the maximal difference was between Beijing and Chengdu (12.9±4.9%). The differences in curve values for femoral neck BMD were relatively small between regions. Compared with the multi-center combined BMD database, the detection rate for lumbar spine osteoporosis was higher by using the Beijing database (17.5% vs. 12.2%, P=0.028), and the rates were lower by using the Jiaxing (23.9% vs. 30.3%, P=0.001), Changsha (30.4% vs. 35.9%, P=0.037) and Chengdu databases (34.8% vs. 41.0%, P=0.032). Conclusion There are geographic differences in female BMD in mainland China, especially for lumbar spine BMD, so multiple regional BMD reference databases should be established in China. |