Bone Disease and HIV/AIDS: More Common Than You Think -- This Month in HIV
An Interview With Todd Brown, M.D., Ph.D., and Ben Young, M.D., Ph.D.
Hello and welcome to This Month in HIV. My name is Bonnie Goldman.
With the remarkable success of HIV treatment comes a renewed focus on other health issues that plague people with HIV. You've probably heard a lot about heart disease and HIV and certainly lipodystrophy and HIV, but bone disease may affect up to 50 percent of HIV-positive people and it is little talked about.
With me to explore this issue is Todd Brown, M.D., Ph.D. Dr. Brown is an endocrinologist and an assistant professor of medicine at Johns Hopkins School of Medicine. He's also one of the top researchers when it comes to bone disease in HIV-positive peoples and has been researching this issue since 2004.
Also with me is one of TheBody.com's online experts, Ben Young, M.D., Ph.D. Dr. Young is an assistant clinical professor of medicine at the University of Colorado. He is also a consultant physician at Denver Infectious Disease Consultants, and as such he'll be able to speak to what he's seeing in what is one of Denver's largest private practices.
"I think the biggest issues now are how to best screen, diagnose and optimally manage people who may have bone disease and HIV."
-- Ben Young, M.D., Ph.D.
Bonnie Goldman: Welcome, Dr. Young and Dr. Brown to This Month in HIV. I want to start with you, Dr. Young. What is the biggest issue you're seeing in your practice today?
Ben Young: Our patients are living much longer, and are much healthier than they were in the earlier pre-HAART [highly active antiretroviral therapy] and early HAART eras. This means that they are now beginning to worry about long-term survival and issues related to aging -- all of which are good things.
In the midst of all of this, though, about four or five years ago, we started seeing one or two patients a year with unexplained fractures. Compression fractures of the vertebrae were the sentinel symptoms of this problem.
At first, we thought that they were just outliers, unusual people with unusual problems, and not part of a larger trend. It was Dr. Brown's analysis in 20061 that brought the magnitude and the frequency of this problem to a head.
The biggest issues now are how to best screen, diagnose and optimally manage people who may have bone disease and HIV. I think this is going to be a very important topic, particularly as our patients age into the next decade of their lives, and so on.
Bonnie Goldman: What percentage of patients in your practice have bone disease?
Ben Young: We'll probably touch on this later, but it was really because of Dr. Brown's meta-analysis that we became concerned about silent bone disease in our practice. That is to say, thinning of the bones and brittle bones -- osteopenia and osteoporosis, respectively. What we detect in patients are fractures.
Obviously, from a preventive medicine standpoint, we like to identify patients who are at risk of having very serious fractures, or fracture risk, before they fracture. So we embarked on a program to try to do just this, namely doing dual energy X-ray absorptiometry, or DXA scanning.
"I've screened about 80 percent of the patients in our practice. ... Over 50 percent of our patients have one form or another of abnormally thin bones. This is a really striking number, much greater than many, many of the other complications that we worry about."
-- Ben Young, M.D., Ph.D.
I've screened about 80 percent of the patients in our practice. What we find is entirely sanguine with Dr. Brown's earlier analysis, which is: Over 50 percent of our patients have one form or another of abnormally thin bones. This is a really striking number, much greater than many, many of the other complications that we worry about.
Bonnie Goldman: When you say "silent," what do you mean? Do you mean no one is experiencing any symptoms?
Ben Young: This is similar to hardening of the arteries, which doesn't cause symptoms until something bad happens. A patient who has osteopenia, for example, should have no symptoms whatsoever. A patient who has osteoporosis frequently doesn't have fractures, right up until the point that he or she fractures a hip or a vertebral body. The real problem is recognizing risk and trying to improve bone health before this fracture.
Bonnie Goldman: Dr. Brown, what made you initiate your investigations into bone disease in the HIV-positive population?
Todd Brown: There had been scattered reports of low bone density among HIV-positive patients. There's some question regarding whether or not it was related to HIV itself, or antiretroviral therapy.
When I was in training at Georgetown University, we had conducted a study2 but it wasn't large enough to be able to draw firm conclusions about the most severe losses in bone mineral density.
"We did find about a 15 percent prevalence of osteoporosis -- the average age was probably the low 40s -- across the various studies that we looked at. Compared to the respective HIV-negative control population, this was about three and a half times the prevalence that was seen in those populations."
-- Todd Brown, M.D., Ph.D.
That's why the meta-analysis was an effective way to do this. We could look at osteoporosis, rather than a combined category of osteopenia, which is a lower than normal bone mineral density, and osteoporosis.
We did find about a 15 percent prevalence of osteoporosis -- the average age was probably the low 40s -- across the various studies that we looked at.
Compared to the respective HIV-negative control population, this was about three and a half times the prevalence that was seen in that population.
Bonnie Goldman: Could you explain what osteopenia and osteoporosis are?
Todd Brown: Bone density is probably the best way, or the most available way, of measuring and evaluating fracture risk using DXA, or dual X-ray energy absorptiometry. Osteoporosis and osteopenia are really designations, or classifications, based on [the bone density of] postmenopausal women. A lot of this research has been done in postmenopausal women just for the simple fact that this is where the burden of fractures lies.
When you look at bone density tests, DXA scans, the measure that most people use is something called the "T-score." This is the number of standard deviations that a person's bone mineral density is away from that of a gender-matched, young, normal population.
If your T-score is more than two-and-a-half standard deviations lower than that of a young, normal population, then you have osteoporosis. You have osteopenia if your T-score is between one standard deviation and 2.5 standard deviations less than that of the young, normal population.
Bonnie Goldman: When you say bone mineral density, are you simply referring to the thickness of someone's bones?
Todd Brown: That's right: the amount of mineral that's in your bones. This designation, as I mentioned, has mostly been validated in postmenopausal women, but has been applied to other populations, as well.
Bonnie Goldman: Postmenopausal women are the most likely to lose bone because of the hormonal changes that occur after they stop menstruating, is that right?
Todd Brown: That's right.
Bonnie Goldman: So, it's really not common in the general population.
Todd Brown: There's not a lot of good, standard data to understand what the bone mineral density is in the average person.
Bonnie Goldman: Dr. Young, is it a challenge to explain bone disease to patients?
My mother, for example, had osteoporosis. That's a precise term: a brittle bone. Often we'll use the terminology of abnormal, but not diseased, bones -- much analogous to HIV without AIDS, for example. It's not particularly complicated for people to understand.
Sometimes the T-score/Z-score standard deviation language can confuse people. But it just indicates how far away from the expected bone density you are. Once you're two-and-a-half standard deviations below that, then we define that as having osteoporosis.
What people should realize is that these scores, the standard deviations, are a continuous variable, in a way, so that the risk of fractures is continuous. It's a function of both the strength of the bones, if you will, and the likelihood that one is going to fall -- a larger component that also influences the risk of having a fracture.
In general, people do understand this. Explaining to them why I'm concerned about assessing them for bone health is not as complicated as some of the other things that we do in HIV medicine.
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This article was provided by TheBody. It is a part of the publication This Month in HIV.
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