Bone loss common in patients with HIV, and often progresses

There is a high prevalence of low bone mineral density among patients with HIV, Spanish investigators report in the online edition of AIDS. The researchers also found evidence during follow-up of deterioration of bone health in many patients.

“Our…study revealed a marked incidence of low BMD [bone mineral density] in a large number of patients with long-term HIV infection and prolonged antiretroviral therapy,” comment the researchers.

They believe that their findings have immediate clinical significance, and write: “Clinical monitoring of BMD by DXA scan should be a priority in HIV-infected patients, specifically in those at risk of fracture.”

HIV infection has been firmly linked with an increased risk of low bone density. However, the exact causes are unclear.

Traditional risk factors for this condition include smoking, heavy alcohol consumption, malnutrition, low body weight, and lack of physical activity.

HIV itself can cause loss of bone mineral, and treatment with some anti-HIV drugs has also been associated with loss of bone mineral density.

Spanish researchers wanted to gain a better understanding of the prevalence, risks and progression of bone loss in their HIV-positive patients.

They therefore designed a retrospective study involving 671 patients who received HIV care between 2000 and 2009 in Barcelona. All the patients had at least one DXA scan. Progression of bone loss was assessed in 391 individuals who had two or more scans.

Most (72%) of the patients were male, 6% were aged over 55, the median age was 42 years (interquartile range 37 to 47), 67% had a body mass index (BMI) within the normal range, 62% had an adequate calcium intake, and 35% were co-infected with hepatitis B or C.

CD4 cell count at the time of entry to the study was 496 cells/mm³, 93% had experience of antiretroviral therapy, and 61% had an undetectable viral load.

The patients had been taking anti-HIV drugs for a median of seven years, 53% were taking a protease inhibitor, and the same proportion of patients took tenofovir (Viread, also in the combination pills Truvada and Atripla).

Osteopenia – mild bone loss – was diagnosed in 47% of patients and osteoporosis – porous bone with an increased risk of fractures – in 23%.

Factors associated with low bone mineral density were increasing age (p < 0.001), low BMI (p < 0.001), male sex (p = 0.0078), high creatinine levels (p = 0.0047), taking HIV therapy at the time of DXA scan (p = 0.007), longer duration of antiretroviral treatment (p = 0.004), and increased amount of time taking a protease inhibitor (p = 0.0001).

Next the investigators looked at the progression of bone loss. Their analysis included the patients who had two or more DXA scans.

The median time between the first and last scan was 2.5 years, but in 27% of patients it was more than five years.

At the first scan, 49% of patients had osteopenia and 22% osteoporosis. At the second scan this had increased to 50% and 27%.

Overall, 29% of patients experienced progression to low bone mineral density, including 13% progressed to osteopenia, and 16% from osteopenia to osteoporosis.

When analysis was restricted to the 105 patients with five or more years of follow-up, 47% lost bone mineral density, including 18% who developed osteopenia and 29% who developed osteoporosis.

Factors associated with bone loss during follow-up included increasing age (p < 0.0001), male sex (p < 0.0001), low BMI (p < 0.0001), longer duration of treatment with a protease inhibitor (p < 0.0001) or tenofovir (p < 0.0001), and taking a protease inhibitor at the time the DXA scan was performed (p < 0.0001).

“We reveal a high prevalence of low BMD in our cohort. The longitudinal analysis – more than five years of follow-up in some cases – revealed rapid progression to demineralization,” comment the investigators.

The investigators stress the need “for close monitoring of BMD, specifically in at-risk patients who are taking antiretroviral therapy that affect bone demineralization”.

Bonjoch A et al. High prevalence of and progression to low bone mineral density in HIV-infected patients: a longitudinal cohort study. AIDS, online edition: DOI: 10.1097/QAD.0b013e328340a28d, 2010 (for access to the study’s free abstract, click here).