Measuring bone density: Who stands to profit from this examination?

Women after menopause have an increased risk of having fragile bones. Drug treatments can strengthen the bones and lower the risk of fracture. Whether women profit from the medications can be assessed by measuring their bone density.

In osteoporosis, bones get more fragile and weaker, especially because the bone tissue loses substance. Osteoporotic bones break much more easily than healthy ones. Even a minor fall can lead to a bone breaking or cracking. The most common type of osteoporosis is primary osteoporosis, which has no specific cause. Especially people with certain risk factors get this disease, for example women after menopause.

Sometimes fragile bones have a specific cause, for example a disease like rheumatism or thyroid hyperfunction. People who take cortisone preparations over a longer period of time are also prone to developing fragile bones. This type of osteoporosis is called secondary osteoporosis. You can find more information about what goes on in the bones in osteoporosis and what other risk factors there are for developing fragile bones in our fact sheet.

Fractures are most common in people over 65 years

Bones of the hips, upper arms, the wrists and the vertebral bodies of the spine are the ones that most commonly break in osteoporosis. Usually people over 65 years are affected: in Germany, 6 to 7 out of 1,000 people in this age group break a hip bone (femoral neck) every year. In people of the same age, the risk of fracture is considerably higher in women than it is in men. Fractures of vertebral bodies do not always lead to symptoms and often remain unnoticed.

Certain drugs slow down the reduction in bone tissue or increase the production of new bone tissue. They can lower the risk of fractures. These medications have different adverse effects, however. It is therefore interesting to find out who benefits from a specific drug treatment or, to put it differently: who has more advantages than disadvantages from taking these drugs. To find this out, bone density is measured. The medical term for this examination is osteodensitometry or bone densitometry.

How bone density is measured

There are several tests to find out whether someone has fragile bones. The so-called dual energy X-ray absorptiometry (DEXA or DXA) is considered to be the most reliable one. When a DEXA is done, the upper thigh bone or the lumbar vertebrae are screened using weak X-rays. Measuring the amount of radiation the bones let through, bone density can be assessed: In lower bone density, more rays pass through then bones than in higher bone density.

In this examination, bone density is usually measured on a scale called the T score. A T score below  2.5 (for example  3 or  3.5) is considered osteoporosis. You can read more about T score and how the examination is done as well as on other bone examinations here.

For women after menopause who have already had a bone fracture, it has already been scientifically proven for some time that they can profit from medications that strengthen the bones. This is why statutory health insurance funds routinely cover the costs for osteodensitometry in these women.

The publisher of this website – the German Institute for Quality and Efficiency in Health Care (IQWiG) – has now looked into the question of whether other people also benefit from having their bone density measured. The researchers wanted to find out whether this examination can also identify people who have brittle bones and might benefit from treatment before they have a fracture.

What the researchers did

To answer this question, researchers from IQWiG and from the University of Lübeck assessed trials on osteodensitometry. However the researchers found hardly any conclusive trials that directly tested the effect osteodensitometry has on the treatment result. So they also systematically looked for treatment trials with people who were diagnosed with reduced bone density by using osteodensitometry before therapy started. So they were able to find indirect evidence on the benefit of osteodensitometry. A measurement taken beforehand could help to assess which people can benefit from drug treatment or another kind of therapy.

The researchers found a total of 15 treatment trials including a total of 25,000 participants. Most participants were women after menopause, however. There were only 2 trials that only included men, and only one trial with people with secondary osteoporosis. There were no conclusive trials on non-drug treatment forms.

Besides the treatment trials, the researchers also looked at trials that studied the reliability of different methods to measure bone density when compared to one another. And they evaluated whether in men there is a similar connection between low bone density and bone fractures as it has already been proven to exist in women. The IQWiG found no trials on the question of whether it makes sense to check bone density regularly during therapy.

Result: Women after menopause could benefit from measuring bone density

The IQWiG found evidence that women after menopause could benefit from having their bone density measured – even if they have not yet had bone fracture typical of osteoporosis. There was evidence that drug treatment had a benefit for women with severely reduced bone density. These women had a T score that was lower than  2.5. In women with higher bone density, there was no benefit of specific drug treatment (with a T score between  1.5 and  2.5). So osteodensitometry could help to identify a group of women who have more advantages than disadvantages from preventive drug treatment. When deciding to have such a treatment it is nevertheless always important to weigh the benefit against the possible adverse effects of the drugs – particularly, because in the end this is a personal decision.

Examination methods: dual energy X-ray absorptiometry (DEXA) found to be the most exact

The IQWiG evaluated various trials that tested whether there are examination methods with reliability similar to dual energy X-ray absorptiometry (DEXA) – the standard method. The researchers found that other methods, for example using ultrasound, were significantly less exact. They concluded that so far there is no equally good examination method that can be used instead of DEXA to diagnose osteoporosis.

Low bone density also increases the risk of fractures in men

The trials on the risk of bone fractures in men evaluated by IQWiG show that there is also a connection between low bone density and hip fractures in men, if bone density of the femoral neck is measured with DEXA. The evaluations done by IQWiG did not however give evidence that men in general or that a certain group of men may benefit from osteodensitometry. In people with secondary osteoporosis, the connection between low bone density and bone fractures has not yet been proven. This is mostly due to the fact that there are hardly any trials on this issue.

There are many possibilities to prevent osteoporosis. You could stop smoking, eat a calcium-rich diet, or do more exercise, for example. To read more about the different options for preventing osteoporosis, click here.

Author: German Institute for Quality and Efficiency in Health Care (IQWiG)

Next planned update: January, 2014. You can find out more about how our health information is updated here.

Note

This health information is a summary of a scientific report published by IQWiG. It is not an assessment of the right to have health care services reimbursed by statutory health insurance funds in Germany. By law, decisions about the reimbursement of diagnostic and therapeutic procedures can only be made by the German Federal Joint Committee (G-BA). The Federal Joint Committee takes IQWiG reports into consideration in its decision-making process. You can find information about the decisions of the German Federal Joint Committee on its English-language website, www.english.g-ba.de.

© IQWiG (Institute for Quality and Efficiency in Health Care)