In the past two years there have been reports of people who use HAART developing the following complications:
Why these problems occur is not clear. Some researchers suspect that the components of HAART — protease inhibitors, nukes and/or non-nukes — and even HIV infection may all play a role. A number of research teams are trying to understand why these bone problems occur. For background information on the possible causes of bone problems in HAART-users and possible solutions, please see TreatmentUpdate 118.
Researchers in Australia have been studying the impact of protease inhibitors (PIs) on the thickness of bones in PHAs. They found that over time the spine of PHAs who used the PI indinavir (Crixivan) became thicker. In contrast, in those PHAs who used the PI nelfinavir (Viracept), the density of their spine remained unchanged. At first glance, the increasing thickness of bone may seem like a good thing but the researchers caution that increased thickness does not necessarily equal increased strength. Indeed, the way that bone is formed and shaped — the architecture of bone — by the body also plays an important role in giving bones their strength. The Australian researchers note that their findings should be interepreted with the following points kept in mind:
Researchers monitored 54 male subjects who were using indinavir- or nelfinavir-containing treatment regimens for about two years. As part of the monitoring process, certain X-ray scans called DEXA (dual energy X-ray absorptiometry) were performed. DEXA was used to measure the thickness of the bones and fat content of the subjects' bodies. It is important to note that the 54 subjects did not have conditions or habits which could decrease the thickness of their bones, including the following:
Nor were subjects taking any of the following supplements or drugs which could strengthen bones and thus cause the researchers to misinterpret the effect of the protease inhibitors:
In addition to these 54 subjects, researchers also collected data from two other groups of PHAs:
Researchers used subjects from the two groups above to get measurements of the thickness of their backbones so that the results could be compared to those from the first group of 54 subjects.
Among the group of 54 subjects who were using indinavir or nelfinavir, researchers found the following:
When researchers compared results between 131 subjects who were using PIs and the 52 who had never used a PI at first they found that the non-PI-users had, on average, thicker spines. When they re-analysed their data taking into account such factors as weight and height of subjects this difference between PI- and non-PI-users disappeared. Their conclusion was that, in general, thinner subjects were more likely to develop osteoporosis than heavier subjects. This finding is similar to that from studies of HIV negative people.
According to the researchers, lean body mass — a term that describes mostly muscle — affects the thickness of bones. In general, the greater the amount of muscle, the thicker the bones, at least in men. In women it appears that the amount of muscle and fat play a role in maintaining the thickness of bones. So the researchers suspect that those subjects who developed thinner bones had relatively low levels of lean body mass when they entered the study.
The research team cautioned that just because the bones of indinavir-users became thicker doesn't necessarily mean that they are stronger. As a result more research is needed in the following areas:
REFERENCE
Nolan D, Upton R, McKinnon E, et al. Stable or increasing bone mineral density in HIV-infected patients treated with nelfinavir or indinavir. AIDS 2001;15(10):1275-1280.
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Copyright © 2001 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284 http://www.catie.ca.
AEGiS is made possible through unrestricted grants from Boehringer Ingelheim, Elton John AIDS Foundation, iMetrikus, Inc., the National Library of Medicine, and donations from users like you. Always watch for outdated information. This article first appeared in 2001. This material is designed to support, not replace, the relationship that exists between you and your doctor.
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