The prevalence of low bone mineral density
(BMD) is similar in HIV-positive and HIV-negative gay men, according to the
results of Dutch research published in the online edition of the Journal of Infectious Diseases. The only
significant risk factor for reduced BMD was low body mass index (BMI).
“HIV infection was not associated with
BMD,” write the authors, “part of the low BMD previously reported in
HIV-infected MSM [men who have sex with men] pre-dates HIV-acquisition.”
Several studies have shown a higher
prevalence of low BMD in HIV-positive people compared to age- and sex-matched
individuals in the general population. The inflammation caused by HIV infection
and the side-effects of some antiretroviral drugs are possible reasons for this
However, Dutch investigators found a high
prevalence of low BMD in HIV-positive gay men who had recently been infected
with HIV. None of these men had any of the biological markers associated with
increased bone turnover.
This led the researchers to postulate that
the low BMD observed in these people pre-dated their infection with HIV.
They therefore designed a study, comparing
bone mineral density in three groups of gay men: those with primary HIV
infection (known infection within the previous six months); men with chronic
HIV infection; and HIV-negative men. The authors also compared biochemical
markers of bone formation between these three groups.
The study was conducted between 2008 and
2011. Bone density was assessed using dual energy X-ray (DEXA) scans.
total of 41 men with primary HIV infection, 106 individuals with chronic HIV
infection and 30 HIV-negative controls were recruited to the study. All were
aged between 20 and 55 years. None had risk factors for low BMD such as
injecting drug use or kidney disease.
T- and Z-scores for bone density at the
lumbar spine, femoral neck of the hip and total hip were calculated. Low BMD
was defined as a Z-score of -2.0 the standard deviation (SD) for healthy age-
and sex- matched controls.
The three study groups were well matched in
terms of age and race. However, HIV-negative men were heavier (82 kg) than
those with primary or chronic HIV infection (74 kg; p = 0.009). BMI also differed
between the HIV-negative (24.4 kg/m2) and HIV-positive (22.7 kg/m2;
p = 0.04) participants.
The prevalence of traditional risk factors
for low BMD was slightly higher among the men with primary HIV infection
compared to the HIV-negative men, but the differences were not significant.
However, some biomarkers of increased bone
turnover did differ between these two groups. Serum phosphate and bone
formation marker P1NP were significantly lower in those with primary HIV
infection compared to the controls (p < 0.001 and p = 0.009 respectively).
The participants with primary HIV infection also had higher levels of alkaline
phosphate (p = 0.04), sex hormone-binding globulin (p = 0.01) and the bone
resorption marker CTX (p = 0.001) than the HIV-negative participants.
Regardless of these findings, the
prevalence of low BMD at one or more anatomical sites did not differ
significantly between the three groups, and was detected in 20% of participants with
primary HIV, 22% of those with chronic HIV infection and 13% of the
HIV-negative controls. The prevalence of low BMD in the control participants was
similar to that observed in other research involving HIV-negative gay men.
“Two antiretroviral pre-exposure
prophylaxis (PrEP) trials reported a 10-14% prevalence of low BMD…in healthy
HIV-seronegative MSM who were at risk for HIV infection,” note the authors. “One
of these studies observed that low BMD was associated with inhalants (i.e.
poppers, amyl nitrates) and amphetamine use.”
With the exception of total hip Z-score in
the HIV-negative controls, the lumbar spine, femoral neck and total hip T- and
Z-scores in all three study groups were significantly less than zero,
“indicating that the average bone density in our study populations was lower
than the average bone density of the…reference population”.
Lumbar spine BMD and T- and Z-scores were
slightly, but not significantly, lower in the men with HIV compared to the
Femoral neck and total hip BMD, T- and
Z-scores did not differ between the HIV-infected men and the HIV-negative
Statistical analysis failed to find any
evidence that the men with HIV had an increased risk of bone mineral density
compared to the control population. Low BMI was, however, a significant risk
factor (p = 0.001 to p < 0.001).
How can these findings be explained?
The authors suggest that it could be
because gay men are more likely than heterosexual men to have “lifestyle
factors for low BMD such as low body weight, smoking, alcohol and recreational
drug use”. They believe this is an important consideration when designing
studies to assess the impact of HIV infection and its treatment on BMD. “To
precisely measure the effect of HIV-infection on BMD in MSM, it is important to
use adequate control groups comprising HIV-negative MSM.”