International variation in proximal femur bone mineral density

Abstract

We observed higher proximal femur bone mineral density (BMD) in European women compared to average values derived from US Caucasian women in the National Health and Nutrition Examination Survey (NHANES) study. Across European centres, Parisian women had lower proximal femur BMD compared to women from Kiel or Sheffield. Proximal femur BMD of US adults (NHANES III) may not accurately reflect that of European women. We examined the heterogeneity of BMD across European and US Caucasian women and across different European populations. Proximal femur BMD was measured in women ages 20-39 years (n=258) and 55-79 years (n=1,426) from three European centres. Cross-calibrated BMD for total hip, femoral neck, trochanter and intertrochanter were examined. International variation in BMD was assessed by comparing means and SDs in the European data with those from the US NHANES III study. European populations were stratified into 5-year age bands to establish individual centre reference intervals. Between-centre differences were assessed using ANOVA and post hoc Fisher's least significant difference tests. European women had higher BMD than US women: The differences were 7.1% to 14.2% (p<0.001) and 0% to 3.9% (p<0.05) in the older and younger women, respectively. Standard deviations for BMD at the different sites were comparable to those for US women. Among older, but not younger European women, proximal femur BMD was significantly lower in French women (Paris) than in women from Germany (Kiel) or the UK (Sheffield) (difference=5.0% to 9.6%, p<0.05). International variation in hip BMD does exist, with international and between-centre differences being less evident at the femoral neck.