15th Report from: 7th Conference on Retroviruses and Opportunistic Infections, San Francisco, Thursday Feb 3

Bone Mineral Density:

Two abstracts (207, 208) presented small studies of bone mineral density (BMD) in HIV-infected subjects with lipodystrophy who were receiving HAART. Both studies showed that a substantial proportion of subjects taking PIs had decreased bone mineral density, which led to diagnoses of osteopenia or osteoporosis. 21% of 64 persons taking a PI in one study, and 28% of 74 patients with VL <400 in the second study. One study found osteopenia and osteoporosis was prevalent among men with lipodystrophy , but does this mean there is an association with lipodystrophy? I don't think the data presented in this study supports that. Decreased BMD could be associated with HIV, the presence of any virus, bad diet, and other factors. But I think its difficult at this point in our knowledge base about BMD to make associations with specific causes. Interventions that help would be calcium supplements, pressure bearing exercise such as weight lifting, running, and walking. As well increasing dietary intake of foods high in calcium may help--green leafy vegetables.

Here are the two abstracts for your own reading pleasure:

Accelerated Bone Mineral Loss in HIV-Infected Patients Receiving Potent Antiretroviral Therapy.

Pablo tebas and others reported on this study exploring decreased bone mineral density in HIV-infected individuals. The use of potent antiretroviral therapy (HAART) has been associated with multiple metabolic complications whose pathogenesis is poorly understood at the present time. There have been anecdotal reports of bone disorders like avascular necrosis of the hip and compression fractures of the lumbar spine in HIV-infected patients receiving HAART.

The study analyzed whole-body, lumbar spine (L_{1}-L_{4}) and proximal femur bone mineral density (BMD) in 122 HIV-infected patients on HAART that included a protease inhibitor (n=64), HIV-infected patients not receiving a protease inhibitor (n=36) and healthy seronegative adults (n=22) using dual energy x-ray absorptiometry.

Men receiving protease inhibitors had higher incidence of osteopenia and/or osteoporosis according to World Health Organization definitions: RR=2.19 (95% confidence interval 1.13-4.23) (p=0.02). 21 percent of patients receiving protease inhibitor containing regimens had severe osteoporosis (z- scores less than 2 SD below normal for age, sex and race) compared with 6% among controls. Subjects receiving protease inhibitors had greater central to appendicular adipose tissue ratios than the other 2 groups (p<0.0001). However, there was no relationship between the central to appendicular fat ratio and the lumbar spine or proximal femur BMD, suggesting that osteoporosis and body fat redistribution are independent side effects of HAART.

Osteopenia and osteoporosis are unique metabolic complications associated with protease inhibitor containing potent antiretroviral regimens, that appear to be independent of adipose tissue maldistribution.

Osteopenia in a Randomized, Multicenter Study of Protease Inhibitor (PI) Substitution in Patients with the Lipodystrophy Syndrome and Well-Controlled HIV Viremia.

J Hoy and others from Australia reported on this study which switched individuals with lipodystrophy and on a protease inhibitor regimen to a PI sparing regimen. After 24 weeks following the switch Hoy looked at the incidence od oeteopenia to see if the switch made a difference. Osteopenia has been observed in patients with diabetes, male hypogonadism and inflammatory bowel disease. It has not been studied in HIV-infected patients to date, despite the presence of elevated insulin, low testosterone and elevated cytokine levels in many patients.

80 HIV-infected patients with lipodystrophy (defined by total body fat <20% on DEXA scanning) and suppressed viremia (viral load <400 copies/ml) enrolled in the PIILR study. Body composition measurements including determination of regional bone mineral densities (BMD) and T- and Z- scores by DEXA scans were performed at screening, weeks 12 and 24 after randomization to either continue the PI based regimen or switch to a non-PI regimen. Osteopenia was defined as a T-score between -1 and -2.5, and osteoporosis as a T-score less than -2.5.

21 of 74 patients (28.4%) had evidence of osteopenia at baseline, and a further 7 (9.5%) had osteoporosis. There was no change in the proportion of individuals with osteopenia, over 24 weeks. There was no significant change from baseline in BMD and T-scores for arms, legs, trunk and total scores and no statistically significant differences by treatment group. There was no association between baseline insulin level, CD4 cell count, duration of antiretroviral therapy, duration of PI use and baseline T-scores.