February 14, 2003
About three years ago, studies began to describe increased rates of thinning of the bones in HIV-infected men. Subsequent studies have confirmed that compared to HIV-negative men, men with HIV are more likely to have osteopenia or osteoporosis. Osteopenia and osteoporosis are, by definition, two stages of loss of bone calcium. Osteoporosis represents the more severe end of the spectrum. The major risk of osteoporosis is an increased risk of bone fractures, such as broken hips and collapsed vertebra, which can be crippling and even life threatening.
Most of the studies to date have been performed in men with HIV infection. However, the risk of osteoporosis is higher in women than in men, and increases dramatically after menopause. As more and more women are living with HIV, and as these women age, it has become increasingly urgent to learn if osteoporosis is a bigger problem for HIV-infected women. Three studies at the 10th CROI addressed bone health in women with HIV. Unfortunately, they did not give a simple answer.
Jacobson and her colleagues and Tufts (abstract 102) reported on women participating in an ongoing nutrition study called the Nutrition for Healthy Living Study. The women had DEXA scans at baseline and again after approximately two years. The type of DEXA used scanned the whole body, which is different from the commonly used approach that measures bone density at the hip and at the lower spine (lumbar spine).
The women studied were predominantly African American (52 percent) and one third were white. The median age was 39. Although normal scores are adjusted for age, the prevalence of osteopenia/osteoporosis increases with age. HIV disease was mild or well controlled with a median CD4 count of 478 and a viral load of 3.2 log (2-3,000). Importantly, many were overweight or even markedly obese with a median BMI of 27.6 (classified as significantly overweight).
At baseline, the African-American women had higher bone mineral density than the white women and osteopenia was more common in the white women, but this was accounted for by body weight. Over the course of follow-up, the women lost approximately 0.5 percent of their bone mineral density. The change was not associated with age, race or the use of HAART. However, it was associated with a loss of body weight, and an increase in CD4 count.
Arnsten and colleagues from the Bronx (abstract 103) reported on a cohort study of middle-aged women they are enrolling. They reported bone mineral density data by DEXA (traditional hip and lumbar spine) on 200 HIV-infected women and 205 controls, in a single cross-sectional ascertainment. The majority of the women were African American and they were quite heavy. The HIV-infected women had a mean BMI of 27.8 (significantly overweight) and the HIV-negative women had a mean BMI of 31.8 (morbidly obese). Almost 89 percent were current or past smokers and about 25 percent had a history of cocaine use.
The average bone mineral density was slightly lower in the HIV-infected women, and osteopenia was more prevalent (30 percent vs. 24 percent). Age, white race, and lower BMI were associated with having osteopenia, but in the multivariate models, HIV infection was not independently statistically significant. When bone density was looked at as a continuous variable, HIV infection did become an independent predictor.
The third study by Yin and colleagues (abstract 766) was much smaller (31 women) but was confined to post-menopausal women with a mean age of 55. They found a high prevalence of osteopenia (32 percent) and of osteoporosis (42 percent). Low bone mineral density was associated with years since HIV diagnosis, white race, lower body weight or BMI, years since menopause, and lack of hormone replacement therapy.
How do we put these three studies together and what should we do about it. Osteopenia does seem to perhaps be more common among HIV-infected women, and this appears to be strongly related to the other risk factors for osteopenia including low weight, white race, smoking and menopausal status. There is no clear answer yet as to whether treatment helps or hurts bone mineral density.
I believe we should be concerned about osteopenia in HIV-infected women and men who have other risk factors for osteopenia. These include low body weight, smoking, age, postmenopausal status and poor nutrition. Fractures with minimal or no trauma are a red flag. Based on some studies, but not yet confirmed, we should consider those with lipoatrophy to be at increased risk.
At least for adults, DEXA scan is the standard way to measure bone mineral density in adults. A baseline scan to look for osteopenia makes sense. The optimal timing of repeat scans remains unknown. DEXA scans to test bone mineral density are available in most clinical settings, but it can be difficult to get insurance to pay for the scan. Often, you need to demonstrate the presence of two or more risk factors to obtain approval for a baseline scan.
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