Low bone density is not associated with aortic calcification

The aging process is associated with an increasing prevalence of osteoporosis and aortic calcification, but it is uncertain if these two conditions are interrelated. We examined the relationship between bone mineral density (BMD) and evidence of aortic calcification on spinal radiographs among 524 Japanese-American women living in Hawaii. The prevalence of aortic calcification increased with age from less than 10% below age 55 to essentially all women over age 75. Unadjusted BMD was significantly lower among women with aortic calcification at all measured sites (distal and proximal radius and calcaneus). However, the differences in BMD between women with and without calcification were diminished and no longer significant after adjustment for age. Aortic calcification was positively associated with body mass index (BMI), systolic blood pressure, diabetes, current smoking, and thiazide use, but negatively associated with physical activity index. Multivariate logistic regression analysis showed that age, systolic blood pressure, physical activity index (protective), and current smoking (common etiological factors for aortic calcification) were independently associated with aortic calcification, whereas BMD (mean Z-score) was not. We conclude that there is little evidence to support a direct relationship between osteoporosis (low BMD) and aortic calcification. Osteoporosis and aortic calcification appear to be independent processes that occur as women age. However, potential confounding factors may be involved, and prospective studies are needed to investigate this issue further.