Study on osteoporosis drug and risk of heartbeat problems

-BMJ Group

01/21/2009- You may have read reports this week that women who take a medicine commonly used for osteoporosis face an increased risk of heart problems. But how big is the risk, and should you worry about it? We take a closer look at the evidence to find out.

What do we know already?

Alendronate (brand name Fosamax) is a medicine for people with weak bones. Everyone's bones get thinner and weaker as they get older. Women's bones get weaker after the menopause. But if your bones are so weak that they break easily, you have a condition called osteoporosis.

There's good evidence that alendronate slows down the rate at which bones get weaker. It means your bones stay strong for longer, and you're less likely to break a bone. But alendronate has side effects and is not suitable for everyone. In the UK, it's mostly used for older women who've already broken one bone.

In a study of alendronate last year, doctors noticed that slightly more women taking the medicine got an irregular heart beat. This is called atrial fibrillation. The main problem with atrial fibrillation is that it puts you at risk of getting blood clots in your blood vessels, which can be dangerous.

Doctors were surprised by this finding, as it hadn't been noticed before. In the 2007 study, the difference was quite small, and could have been down to chance. So researchers have carried out another study to see whether there really is a link between atrial fibrillation and alendronate.

What does the new study say?

The new study compared a group of women who had atrial fibrillation with a similar group of women who didn't have atrial fibrillation. They found that women who had atrial fibrillation were more likely to have taken alendronate than women who didn't have it.

Tell me more about the study's findings

The study showed that 6.5 percent of women with atrial fibrillation had taken alendronate, compared to 4.1 percent of women who didn't have atrial fibrillation. This means that women who'd taken alendronate were 86 percent more likely to get atrial fibrillation.

The risks were greatest for women who had diabetes, or who were taking medicines called statins, which are prescribed for women at risk of heart disease. This makes sense, because these women would have already had a greater risk of getting heart problems like atrial fibrillation.

The risk applied to women who were currently taking alendronate, as well as those who had taken it in the past.

Where does the study come from?

The study was carried out in the US at the University of Washington, Seattle, and the University of California, San Francisco. It was published in the Archives of Internal Medicine, a medical journal owned by the American Medical Association.

How reliable are the findings?

The study is reliable enough to show there may be a link between alendronate and atrial fibrillation. However, this type of study can't tell us for sure that alendronate actually causes atrial fibrillation. That's because women who took alendronate might have been different in other ways, for example, they might have had another condition that affected their heart, which caused atrial fibrillation. The researchers tried to take account of this in their calculations. But we can't altogether rule out another cause.

Also, other studies have looked at women with atrial fibrillation and have come to different conclusions. A study earlier this year looking at alendronate and similar medicines (known as bisphosphonates) didn't find any link.

What does this mean for me?

It's always alarming to read stories saying that medicines may cause worrying side effects. But it's important to keep these findings in perspective. The increase in risk may not affect you. For example, in the previous study, 1 in 100 women who didn't take alendronate got atrial fibrillation compared to 1 in 100 to 2 in 100 women who did take the drug. So, 98 in 100 to 99 in 100 women who took alendronate in this study were fine.

You also need to remember why you're taking the medicine. Broken bones, particularly hip fractures, can be very serious for older people. They can be very painful and take a long time to recover from. The researchers say that for most people at high risk of breaking a bone, the benefits of taking alendronate are more important than the risks of getting atrial fibrillation.

However, for some people with heart problems like diabetes, the risk of atrial fibrillation may be bigger than the risk of breaking a bone. You and your doctor need to consider carefully which risk is more important for you.

This study only looked at alendronate. We don't know if there is any link between similar medicines for osteoporosis and atrial fibrillation.

What should I do now?

There's no need to take immediate action as a result of this study. If you are taking alendronate, and you are concerned about the risk, make a routine appointment to see your doctor. Talk with your doctor about the benefits and risks to you personally.

From:

Heckbert SR, Li G, Cummings SR, et al. Use of alendronate and risk of incident atrial fibrillation in women. Archives of Internal Medicine. 2008; 168 :826-831.