Osteoporosis risk high in India

Published : Jan 16, 2004 00:00 IST



Interview with Prof. John A. Eisman.

"With every major osteoporosis fracture, the risk of death doubles. Yet it is not taken seriously the world over," says Professor John Allan Eisman, Director, Bone and Mineral Research Programme, Garvan Institute of Medical Research, and Professor of Medicine, University of New South Wales, Sydney. One of the first researchers to identify the gene that causes osteoporosis, Prof. Eisman has written over a hundred research papers in international scientific journals. He is on the editorial board of several international scientific journals, including the Journal of Bone and Mineral Research and Osteoporosis International. He has held several prestigious international positions including as Chairman, Department of Endocrinology, St. Vincent's Hospital, Sydney; and Fellow, Swiss National Fund at Bern, Switzerland (along with Prof. Herbert Fleisch). Eisman, who was in Chennai to attend an international conference, spoke to Asha Krishnakumar on the causes, effects, incidence, treatment options and cost of osteoporosis. Excerpts from the interview:

What is osteoporosis?

Osteoporosis is the thinning and weakening of the bones that leads to their breaking even with minimum force. It is not a disease and you do not get it suddenly. People with osteoporosis may have a fracture (of the arms, legs, wrist, hip and spine) and it heals normally. But then they have more and more fractures and the incidence increases as they get older. Of course, normally bones get weaker as one grows older and the risk of fracture increases. But if one starts off with bones not very strong - that is, osteoporosis - then the risk of fracture gets higher.

And, most important, after almost all these fractures, the person's risk of death increases significantly. We do not understand the reason yet, but for almost all osteoporosis fractures the person's risk of death doubles compared to that of a non-osteoporosis person of the same age and similar circumstances.

What are the symptoms of osteoporosis?

Absolutely nothing until you break a bone. It is something like cholesterol, which can be high but you have no symptom until you have a heart attack or you drop dead.

How can it be diagnosed?

Sometimes it can be seen on an X-ray when there is a lot of bone loss. Then there are techniques such as bone densitometry, with which the density of the bones can be measured. This gives a good index of the risk.

We measure the bone density and find out how far it is away from normal ones. About every 10 per cent away from the normal, the risk of fracture doubles; 20 per cent away, the risk is four times; 30 per cent away, the risk is eight times; and so on. So, the risk increases dramatically as the quality of bones decreases.

What are the most common causes of osteoporosis?

It is so common in the world that it is hard to estimate the causes.

What is the incidence of osteoporosis? Does it vary with sex, age, ethnicity and environment?

The incidence, in general, is higher among women and older people. The reason it is lower among men is that their bones are bigger and hence less likely to break. And also, men tend to live not as long as women. But now as men also tend to live longer, the incidence among them is also increasing.

In Australia, women have a 50 per cent chance of having an osteoporosis fracture before they die. It is also quite common among men - one in three or four gets an osteoporosis fracture.

There are two interesting points about the disease in India - the high incidence among men and the lower age of peak incidence compared to Western countries.

Data suggest that the incidence of hip fracture - which is easily picked up by epidemiology studies as those with hip fractures end up in hospitals - is one woman to one man in India, while in places like Australia it is three women to one man. And in most Western countries, while the peak incidence of osteoporosis occurs at about 70-80 years of age, in India it may afflict those 10-20 years younger, at age 50-60. But we do not yet know why.

According to estimates, there are about 300 million people with osteoporosis in India. I suspect it may be more - over double the population of Australia. The evidence based on ageing population indicates that there may be a 50 per cent increase in the number of people with osteoporosis in India in the next 10 years. So, this is a huge problem in India.

What are the major risk factors in getting osteoporosis?

In any general population anywhere in the world, everything being the same, the biggest risk is genetic. A large number of those affected - maybe three-fourths - inherit it. General health appears to be important. In India, a large number of middle-class people have relatively low vitamin-D - nearly 70 per cent of the people have levels that in Australia would be termed as being severely deficient. A number of factors may be responsible for this. One of them may be the skin colour (pigmentation). As people become more affluent, they spend less time outside and hence have less exposure to sunlight. I am not sure if fog and pollution act as sunscreens.

The other suggestion is that people's calcium intake may not be particularly high. Though dairy products (which has a high level of calcium) are an important part of the food intake here, some people tend to become intolerant to lactose because of bacteria infection that causes stomach upset and move away from these products, and hence have low levels of calcium. Some start on soya drinks for reasons not entirely clear. But soya milk has no calcium in it.

The one thing that is very good for osteoporosis is physical activity. As affluence increases, people do much less walking, standing and so on. That may have an adverse effect and is a major contributory factor.

For women, there is a particularly important factor - menopause. During this phase, they lose bones rapidly for 5-10 years. Bones are like retirement fund. If you are in the upper part of the fund, then it will last you for life. But if you are in the middle or the lower part, you can run into problems quite early or have major problems if you live long enough.

Have the genes responsible for osteoporosis been identified?

Some have been identified. But these still only explain very little of the problem. So probably a range of genes are involved. These are not mutations or disease per se, but predispositions in some way.

How much of a risk does the environment pose?

It is important. But still it explains only part of the problem. There is a huge gap between what we know and what we don't. Probably important is the interaction between the genetic make-up and the environment.

Are there geographical or ethnic differences in the incidence of osteoporosis?

There are huge ethnic differences. In the United States, Afro-Americans have a relatively lower incidence than Caucasians. The Chinese have a slightly higher incidence. Whether these are all due to genetic differences, we do not know. A study in Europe showed the incidence of hip fracture to be very high in the Scandinavian countries compared to those in the Mediterranean nations. The difference was very big. In Europe, women have two-three times higher risk of hip fracture compared to men. In such places as Turkey, the incidence is low and the risk the same between men and women. We do not know why. So a man in a Scandinavian country has a higher risk of a hip fracture than a woman in Turkey and we have no explanation as yet for this.

What are the treatment options available?

There are lots of treatments now that are very well studied and shown to be effective and largely safe. For example, in the case of women, sex hormone replacement therapy can stop bone loss and even reverse it in part. This can also be maintained if the treatment is continued.

But there has been a lot of controversy the world over in using hormonal replacement therapy (HRT), particularly after the Women's Health Initiative study. What are your views on that?

Nothing is without side-effects. There is always an element of risk in whatever we do. There are a lot of studies - the Women's Health Initiative study, the Million Women study and so on - looking at risk factors in using HRT. These studies show that there is a small risk in the diagnosis of breast cancer - less than one in a thousand women a year. It is not a high risk. In the Women's Health Initiative study there was a clear reduction in all sorts of osteoporosis fractures, including those of the hip. But based on a composite index of all the data that researchers thought were important, the Women's Health Initiative study concluded that there was no advantage of being on HRT. But the researchers had left out almost all osteoporosis fractures while working out the index. If one looks at the study, one would think that patients were dying and hence they had to stop the study. But if you look at the mortality graph from the study, it was noticed that HRT and the placebo were virtually identical. But if you read the study you would think that taking HRT is such a dreadful thing. I think it is more because of misinterpretation of the data.

However, I think it is best to inform patients about HRT and let them take an informed decision. I have (osteoporosis) patients who have been taking HRT for 15-20 years and are very happy. They do not want to take a chance (and discontinue).

Are there other options apart from HRT?

There are a group of drugs called SERM (Selective Estrogen Receptive Modulators) that have a protective effect on the bone.

What precautions or preventive measures can be taken against osteoporosis?

In youth, it is important to have good physical activity, good intake of calcium, enough exposure to sunlight, no smoking and so on. Women around menopause should be thinking about hormone replacement for both symptoms and to some extent protection. This should be the case particularly if the woman has a family history of osteoporosis. Getting a bone density test done is a good way of knowing the risk. As women get older, there are drugs such as SERM that seem to have a protective effect on bones.

As you get older, the bones get worse. Another group of drugs - bisphosphonates (Ilendronate and Risresidronate) - only work on the bones. If you take an injection, half of it goes to the bones and the rest gets excreted. These drugs are very good at slowing the loss of bones as they get older. In fact, the bone improves a bit.

How can bones improve as you get older?

Bones are constantly changing. They are constantly being removed and replaced. Half your whole skeleton is replaced every 10 years. The body constantly monitors it, working where there are weaknesses by removing and repairing it. It is like the maintenance programme that is always on. The problem is that as one gets older the rate of this process seems to increase and the ability of the body to replace what is removed has not kept pace. That is why there is bone loss as one gets older. In the case of women, the rate of this process increases during menopause. Things like hormone treatment and SERMs seem to slow this rate of removal and allow the bones to replace enough; improve a bit, and then maintain it. There may not be huge improvement, but certainly some improvement. All studies show that this is enough to reduce half the risk of fractures.

We cannot take a 70-year-old skeleton and make it look like a 30-year-old one. But we can put back about 10 per cent if somebody has lost 20-30 per cent of the skeleton compared to when they were younger. This is consistent with many different agents. This can reduce the risk of almost every sort of fracture depending on the drug used. Clearly, there are things that work and are effective.

Until very recently we did not have any drug to treat someone who has lost a lot of bones. Now, Teriparatide, an injection given once a day, is prescribed for 12-18 months. This is a variation of a normal hormone we all have, called the parathyroid, which, with continuous high levels (during some diseases) leads to the loss of bones. With the injection every day, the bones actually improve at a much better rate than with any other treatment. This dramatically reduces the risk of bone loss. But if you stop it, then you start to lose the bone again. Then in most situations the patients follow other treatments such as bisphosphonates to retain and maintain what you got.

Thus there are immense treatment options today than there were a few years ago. For people in India and in most other countries, we have to think of the simple vitamin D from sunlight, tablets or injections as the solution.

The best way is to concentrate on children around puberty or just before and make sure they get a lot of physical activity, enough sunlight, adequate calcium and so on, so that they get better bones that would help them later in life - like a better bank balance compared to what their capacities are.

Do these treatment methods have side-effects?

Nothing comes without side-effects. People have reported bad cases of ulcer with the use of bisphosphanates that are now used once a week and have to be taken in a very specific way. With SERMs, people have reported clots in the legs. This is not a big risk. But people have got to know the risks.

How expensive are the treatment methods?

It depends on the treatment options. But more than cost considerations, the fact is that people do not take osteoporosis seriously as it is generally thought of as an old age problem particularly prevalent among women. I think it is a lousy neglect of human rights. That is why I think India can lead the world in this as osteoporosis occurs here earlier and also affects almost as many men as women. So India should see the need to deal with it urgently.

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