There is an increased prevalence of osteoporosis and osteopenia in young HIV-positive men, Spanish researchers report in the online edition of the Journal of Acquired Immune Deficiency Syndromes. The study also showed that a low nadir CD4 cell count and therapy with a protease inhibitor were associated with lower peak bone mass.
“HIV-infected men showed lower hip T score and a higher prevalence of osteopenia and osteoporosis than HIV-uninfected controls,” write the authors. “Peak bone mass was inversely associated with nadir CD4 T-cell counts and the use of protease inhibitors, but directly associated with fat and lean mass.”
Low bone mineral density is a recognised complication of HIV infection. Causes are thought to include traditional risk factors such as smoking and drug use, the inflammatory effects of HIV itself, and the side-effects of some antiretroviral drugs.
Bone mass reaches a peak at the end of skeletal maturation. Up to 90% of bone mass is acquired by the age of 18 in females and the age of 20 in males. By age 30, everyone has reached their peak bone mass. It is well known that low peak bone mass is associated with an increased risk of osteoporosis and bone fractures.
Given the accumulating evidence that HIV infection is associated with low bone mineral density and an increased risk of fractures, a team of Spanish investigators designed an observational study comparing bone mineral density and T-scores in the lumbar spine and femur between HIV-positive young adults and age- and sex-matched HIV-negative controls. They also examined the risk factors for low bone mineral density in the HIV-positive participants.
Bone mineral density was measured using dual-energy X-ray absorptiometry (DEXA) scanning.
The study population comprised 232 HIV-positive participants and 75 HIV-negative controls. All were aged between 20 and 30 years and approximately three-quarters were male. Individuals with a very low (16 kg/m2 or below) or a very high (above 28 kg/m2) body mass index were excluded from participation, as were those with comorbidities known to increase the risk of bone metabolism problems.
Data concerning risk factors for low bone mineral density were available for 50% of the participants and 40% of the controls. As expected, individuals with HIV were more likely to be smokers than the HIV-negative controls (57 vs 13%, p =0.012), and were also were more likely to use drugs (15 vs 3%) and drink alcohol (20 vs 3%, p = 0.04). HIV-positive women were more likely to report the use of hormonal contraception (20 vs 0%, p = 0.05). Similar proportions of HIV-positive and HIV-negative participants reported regular exercise (48 vs 40%), which is known to protect again low bone mineral density.
Two-thirds of the HIV-positive participants were gay men and 94% were receiving antiretroviral therapy.
No differences in bone mineral density were found at any site between the HIV-positive and the HIV-negative individuals. The authors were “surprised” by this finding.
However, the mean total T-score in the femur was significantly lower in the HIV-positive participants than in the controls (-0.2 standard deviation [SD] vs +0.05 SD, p = 0.018).
Osteoporosis was present in 11% of the patients and 4% of controls. Osteopenia was detected in 57% of individuals with HIV infection and in 51% of the uninfected controls.
Normal bone mineral density was present in only a third of the HIV-positive participants, which was significantly lower than the prevalence in the controls (45%, p = 0.019).
“Increasing numbers of children and adults are affected by low BMD [bone mineral density], probably because secondary forms are becoming more common as a result of lifestyle, diet, chronic illness and medication,” note the investigators.
Analysis of the results according to gender showed that osteoporosis was more common in HIV-positive men compared to control men (12 vs 6%, p = 0.033), as was osteopenia (57 vs 46%, p = 0.014).
Mean total femoral T-score was -0.3 SD in HIV-infected men compared to +0.1 SD in the control men (p = 0.03).
Bone mineral density, T-score and the prevalence of osteopenia and osteoporosis were similar between the HIV-positive and HIV-negative women.
A low nadir CD4 cell count and therapy with a protease inhibitor were associated with lower peak bone mass in the lumbar spine and total femor (p = 0.022 and p = 0.005, respectively).
The authors suggest the “negative effect of low nadir CD4 T-cell count on BMD could be explained by the high levels of immune activation and inflammation usually associated with severe immunodeficiency”.
However, total lean mass and total fat mass were associated with increased bone density at all sites.
“Since lean mass is strongly related to physical activity, it is clear that exercise is an important component in the prevention of bone loss,” the researchers comment and they suggest exercise should be “strongly recommended in HIV-infected patients from the very early stages of the infection”.
They conclude: “Considering that this young population will be living with HIV infection for many years, risk factors for osteoporosis should be modified, if possible.”
Negredo E et al. Peak bone mass in young HIV-infected patients compared with healthy controls. J Acquir Immune Defic Syndr, online edition, doi: 10.1097/1.qai.0000435598.20104.d6, 2013.