An important marker of
sub-clinical cardiovascular risk is associated with reduced bone mineral
density in the hips of HIV-positive patients, according to Italian research
presented to the Sixth International AIDS Society conference (IAS 2011) in Rome.
found that calcification
– of the coronary artery was associated with low bone density in the
“The cross correlation
between bone demineralisation and subclinical atherosclerosis is of interest in
light of the accelerated bone demineralisation and high fracture rate noted in
HIV-infected subjects along with increased cardiovascular risk,” Dr Antonio
Bellasi of the Metabolic Clinic, University of Modena
and Reggio Emilia, told delegates.
and changes in bone metabolism are current hot topics in HIV care.
Research conducted in
HIV-negative patients has found that individuals with reduced bone mineral
density are also more likely to have hardening of the coronary artery. This
association appears to be of clinical significance. Post-menopausal women with
osteoporosis are known to have an increased risk of a cardiovascular event.
Moreover, both hardening of the arteries and osteoporosis have a similar
pathology, and they are also share risk factors
– for example low levels of
vitamin D, a highly prevalent condition in HIV-positive people.
However, little is
known about the association between calcification of the coronary artery and
bone mineral density in HIV-positive patients.
investigators therefore undertook a study involving 812 patients who received
care between 2006 and 2010.
They hypothesised that
there would be a relationship between cardiovascular and bone complications in
None of the patients
had a history of cardiovascular disease. After monitoring, the patients were
divided into two groups dependent on their coronary artery calcification score
(above or below 100, the higher score indicating more hardening of the artery).
Bone mineral density
was also measured in the lower spine and femoral neck of the hip. An individual
was defined as having low bone mineral density if this was below the 25th
Hardening of the
coronary artery was associated with a number of traditional risk factors
including older age, male sex, poorer kidney function, diabetes, high blood
pressure, a high ten-year Framingham risk score, and high body mass index.
There was a higher
prevalence of low bone mineral density in the hip among patients with a
coronary artery calcification score above 100 than in patients with a score
below 100 (23 vs 15%).
However, reduced bone
mineral in the lower spine was comparable between patients with higher and
lower calcification scores (16 vs 15%).
A series of
statistical analyses were then performed to see which factors were associated
with hardening of the coronary artery and reduced bone density in the hip.
The first model found
a near-significant association between age and sex (odds ratio [OR] = 1.73; 95%
CI, 0.88-3.38, p = 0.10).
A second model added
risk factors for cardiovascular disease such as a high body mass index, diabetes and a high Framingham score, and the result found an increased risk that fell just short of statistical significance (OR =
2.01; 95% CI, 0.97-4.19, p = 0.06).
factors, including CD4 cell count, viral load and treatment with tenofovir (Viread, also in the combination pills Truvada and Atripla), made the association significant (OR = 2.33; 95% CI,
1.11-4.86, p = 0.02).
The final model, including kidney function, vitamin D
levels, and thyroid function had little impact on this finding (OR = 2.33; 95%
CI, 1.09-4.99, p = 0.02).
A 'bootstrap' analysis
that compensated for the low number of recorded events confirmed the robustness
of the investigators’ findings. It also underlined the significance of
traditional risk factors such as age, kidney function and diabetes to coronary
calcification and reduced bone mineral density in the femoral neck of the hip.
The investigators were
unable to explain why hardening of the coronary artery was associated with
reduced bone density in the hip, but not in the spine.
emphasised that lifestyle changes such as regular exercise, a good diet, and
stopping smoking could reduce both cardiovascular and bone problems in
patients with HIV.
Dr Bellasi concluded,
“future studies should test the hypothesis that therapies that attenuate
cardiovascular risk in HIV may also favourably impact bone mineral density in