Research On The Relationship Between Body Mass Index And Hip Fracture In Chinese Women

Aim:Hip fracture (HF) is a major public health concern in aging population and body mass index (BMI) is one of the important risk factors for HF. In general, low BMI is believed to be a significant risk factor in HF; for high BMI the opposite is true. However, there are few investigations on the relationship between BMI and HF in Asian. Previous researches on the relationship between BMI and HF risk in Chinese cant present the magnitude of HF risk change resulted from BMI variation.Previous investigations revealed that Caucasian with high BMI possess higher BMD and more favorable hip BGP. However little is known about the detailed relationship between BMI and BMD as well as BGP in Chinese.The current research aimed at investigation on the relationship between BMI and HF risk in Chinese to provide useful information for clinical purpose. Subjects and methods:There were two major groups of subjects, groupⅠand groupⅡ. The participants in groupⅠwere 669 Chinese Han women including 280 HF subjects and 389 none-fracture subjects. Logistic regressions were performed by treating the fracture status as the dependent variable, age and BMI as covariates. GroupⅡis made up of 874 Chinese Han women. Simple linear regressions were performed by treating BMI as the independent variable, BMD and 5 BGPs as dependent variable, respectively.Results:On average, for each unit increase in BMI, the HF risk decreased by 14%:OR 0.86 (95% CI,0.81-0.91). Compared with normal BMI (18.5kg/m2≤BMI<25. Okg/m2) type, the HF risk in low BMI (15.0kg/m2≤BMI<18.5kg/m2) type is 33% higher than that in the former, OR:1.33 (95% CI,0.64-2.76); while that of high BMI (25.0 kg/m2≤BMI<36.0 kg/m2) type is 35% of that in normal BMI type, OR 0.35(95% CI,0.21-0.56). In addition, for each unite increase in BMI, the BMD, CSA, CT, SM and BR of femoral neck changed by 0.0097,0.0314,0.0019,0.0168 and -0.1152 units, respectively.Conclusion:In conclusion, the risk of HF decreases with increasing BMI; compared with normal BMI type, the HF risk is higher in low BMI type, lower in high BMI type. Probably, the higher BMD and more favorable bone geometry paprameters in higher BMI type partially attributed to this phenomenon.