Q&A: The impact of low bone mineral density

Video transcript

This transcript has been lightly edited for clarity

How does low bone mineral density contribute to the global burden of disease?

Low bone mineral density is not one of the well-known risk factors to health. It has a particular effect on bones, as the name already suggests. And it makes bones weaker and, therefore, more vulnerable to fracture. And because falls are a very important contributor to death and disability at older ages, it contributes a considerable amount of health loss in the world.

What were the key findings of the study?

The key finding is, as I mentioned, the large impact of low bone mineral density on the outcome of falls. But also, we have quantified how much is contributed by road traffic accidents. And where traditionally people said, oh, if you have brittle bones, with road traffic accidents, it doesn’t make a difference because that’s a high-impact injury and therefore you don’t get it because you have brittle bones. But we’re now suggesting that there is – not as large as for falls – but there is a considerable amount of burden also associated with road traffic accidents.

You see, age by age, what the value of bone mineral density is. Higher values, stronger bones. Lower value is brittle bones. And then you can see that, in red, women have much lower values at every age than men, but that in men and women these values tend to drop with age, and hence the much greater risk at older ages of being affected by these brittle bones.

And so you can see there that the top age in females is around age 70, whereas it’s a much flatter pattern for males and much lower numbers in the elderly.

And you can see also the dominant position of falls across the whole age range, much more so in females than in males, and a much greater contribution, in yellow, by road traffic accidents in males.

Where do we see the greatest impact of low bone mineral density?

When we age-standardize, we take out the differences in population structure between countries. And, thus, we make the estimates between countries that have a very young or a very old population more comparable. So what you can see in this graph is that in many

parts of the high-income world, the rates of health loss in disability-adjusted life years are relatively similar – in that light pinkish color.

There are a number of parts of the world where these rates are much higher, particularly India, Saudi Arabia, a few countries in Africa, and look also at Greenland.

If we look at the bottom map, then we see similar countries lighting up with high estimates, but more so in the poorer countries of sub-Saharan Africa, with darker shades and, therefore, higher death rates. And that suggests that if you sustain a fracture in a lower- income country, you’re more likely to die from it – and so the case-fatality rate of fractures is greater. And that, then, is an important contributor to the overall amount of health loss.

What can be done to improve things?

There is a relatively easy and cheap method of measuring the density of your bones. And when you can determine that someone has low bone mineral density, then [things can be improved] partly through lifestyle factors and maybe supplementing with some calcium in case that is a problem. You can also target people who have the lowest values with particular drug therapy that makes your bones denser and hence protects you from some of these ill effects of the fractures.

So, we have a relatively easy way of determining bone mineral density. There are relatively effective medications to deal with the problem. And hence, there’s opportunity to address health problems through more targeted action.