Bone mineral density and the risk of peripheral arterial disease in men and women: results from Mr. and Ms Os, Hong Kong

Previous population studies have demonstrated an association between peripheral vascular disease and bone mineral density in women, but not in men. In a large prospective cohort of 3,998 Chinese men and women aged 65 to 92 years of age in Hong Kong, the association between peripheral vascular disease and bone mineral density was explored. Demographic and lifestyle information was obtained from face to face interviews using a standardized questionnaire. This included demographic information, medical history and lifestyle factors. Physical examination measurements included anthropometry and tibial and brachial systolic blood pressures. The ratio of the posterior tibial and brachial systolic blood pressures, the ankle/arm index, was used as a measure of peripheral arteriosclerosis in the lower extremities. Bone mineral density (BMD) at the total hip and spine (L₁–L₄) was measured by Hologic QDR-4500 W densitometers (Hologic, Inc., Waltham, Mass.). In this cross-sectional analysis, the ankle brachial index (ABI) was positively correlated with hip BMD (correlation coefficient=0.27; P <0.001). However, after adjustment for confounders, the correlation became much weaker (correlation coefficient=0.03; P <0.05). This showed that much of the relationship between ABI and BMD could be explained by other confounders. In multiple regression analysis, an increase in ABI of 1 SD of ABI was associated with an increase of 0.5% (95% CI: 0.02%, 0.9%) in hip BMD after adjusting for age, sex, body weight, smoking status, history of diabetes, cardiovascular diseases, use of thiazide diuretics, grip strength and physical activity. Although our study shows that peripheral vascular disease in the lower extremities may be associated with decreased bone mineral density, the association is weak especially after adjustment was made for confounders. This indicates that other factors may be contributing to the association between peripheral vascular disease and osteoporosis.