Endocrine Abstracts

Background: Vitamin D deficiency/insufficiency and adiposity have deleterious effects on skeletal health and can increase arterial stiffness. Additionally, low bone mass is associated with increased arterial disease, but little is known about the association of bone geometry with arterial disease.

Objective: To determine the association between bone geometry and arterial stiffness in overweight (body mass index >25 kg/m²], older adults [50–80 years] with vitamin D insufficiency [<50 nmol/l].

Methods: Cross-sectional analysis. Demographics and clinical history were obtained via questionnaires and anthropometric data were obtained using standard protocols. Tibial bone geometry in the tibia at the 4% and 66% sites was assessed via peripheral quantitative computed tomography [XCT3000, Stratec, Germany]. Blood pressure and measures of arterial stiffness were determined by an oscillometric device [Mobil-o-Graph, IEM, Germany]. These measures included pulse wave velocity [velocity at which arterial pulse propagates throughout the vasculature], augmentation index [proportion of blood pressure waveform attributable to the reflection wave] and pulse pressure [difference between systolic and diastolic blood pressure]

Results: Thirty individuals were recruited [mean age: 57.7±6.3; women: n=15(50%)]. Mean systolic blood pressure was high-normal [128.6±13.5 mmHg]. In age and BMI adjusted models, there was an inverse correlation between trabecular area at 4% site [r=−0.80; P<0.001]; trabecular volumetric bone mineral density [r=−0.58; P=0.003]; cortical area at 66% site [r=−0.55; P=0.008]; fracture load(x) [r=−0.47; P=0.028]; fracture load(y) [r=−0.69; P<0.001] with augmentation index. Additionally, there was an inverse correlation between trabecular area at 4% site [r=−0.42; P=0.027] and cortical area at 66% site [r=−0.449; P=0.018] with pulse pressure. Bone marrow density correlated positively with pulse pressure [r=0.448; P=0.021]. In multivariate regression analyses adjusting for age, BMI and sex, trabecular area was inversely associated with augmentation index [β=−5.67; 95% confidence interval: −8.81, −2.43].

Conclusion: Poorer bone geometry was strongly negatively related with augmentation index, a measure of systemic arterial stiffness. This provides further evidence for an association between bone loss and changes in arterial stiffness that act to increase vascular risk. A randomised trial is now required to determine if an intervention to reduce underlying adiposity and correct vitamin D deficiency will improve these outcomes.