Associations between hip bone mineral density, aortic calcification and cardiac workload in community-dwelling older Australians.

Abstract

To determine whether there is an association between lower bone mineral density (BMD) and increased cardiac workload in older adults, and if this association was independent of abdominal aortic calcification (AAC). Three hundred thirty-seven participants [mean±SD age=70±5years and BMI=28±5kg/m2, 61% females] had BMD determined by dual-energy X-ray absorptiometry and AAC determined by radiography. Aortic calcification score (ACS) was determined visually in the L1-L4 vertebrae (range 0-24). Systolic blood pressure (BP) and heart rate (HR) were measured. The rate pressure product (RPP), a measure of cardiac workload, was determined by multiplying BP and HR. AAC was present in 205 (61%) participants. Mean±SD RPP was 9120±1823; range was 5424-18,537. In all participants, ACS was positively associated with log-transformed RPP [LnRPP] (β=0.011, p<0.001), and severe calcification was positively associated with LnRPP (β=0.083, p=0.004 relative to no calcification). In sex-stratified analyses, these associations were significant only in females. Lower odds of any AAC were observed per 1g/cm2 increment in femoral neck BMD (OR=0.08, 95% CI 0.01-0.95). A similar trend was evident in women separately (OR=0.05, 95% CI 0-1.17) but not men. In all participants, femoral neck (β=-0.20, p=0.04) and total hip BMD (β=-0.17, p=0.04) were inversely associated with LnRPP after multivariate adjustment. Adjusting additionally for AAC reduced the strength of the association in femoral neck (β=-0.19, p=0.05) but not total hip BMD (β=-0.17, p=0.04). Lower BMD was marginally, but significantly with increased LnRPP, and this relationship was partially mediated by AAC suggesting that older adults, particularly females, with osteoporosis may have an increased cardiovascular risk.