Femoral neck and spine bone mineral density-Surrogate marker of aortic calcification in postmenopausal women

OBJECTIVE Osteoporosis and abdominal aortic calcification (AAC) are associated with increased morbidity and mortality in postmenopausal women. The aim of this study was to determine the accuracy of anterior-posterior (AP) dual-energy X-ray absorptiometry (DXA) compared with that of X-ray lateral lumbar radiography (LLR) in detecting and scoring AAC. METHODS In this cross-sectional study conducted in 56 postmenopausal asymptomatic females aged 59.0 ± 9.3 years and who never used medications to treat osteoporosis before, we determined femoral neck and lumbar spine bone mineral density (BMD) by AP DXA and AAC by X-ray LLR. We hypothesized that the subtracted femoral neck BMD (BMDFN) from lumbar spine BMD (BMDLS) presented as ΔBMD=BMDLS-BMDFN would have a diagnostic value in detecting abdominal vascular calcification. RESULTS The mean BMDFN was 0.744 ± 0.184 g/cm(2), and the mean BMDLS was 0.833 ± 0.157 g/cm(2) (p<0.0001); the mean ΔBMD was 0.089 ± 0.077 g/cm(2), and the mean AAC score was 2.182 ± 1.982. Bivariate Pearson's correlation analysis revealed a significant positive correlation between AAC and ΔBMD (r=0.449, p=0.0006); by linear regression analysis, R(2)=0.2019, and by multiple regression analysis, βst=13.5244 (p<0.0001). We found a sensitivity of 64.3% and specificity of 82.9% by receiver operating characteristic [ROC; area under the ROC curve (AUC=0.759)] in the prediction of AAC by ΔBMD. CONCLUSION This AP subtracting BMD DXA method provides a useful tool for detecting and scoring subclinical and extensive AAC in postmenopausal women using a simple, semiquantitative, and accurate scoring system with minimal radiation exposure and low cost.