Heartburn drugs may raise risk of pneumonia

BMJ Group News

Drugs taken by millions to prevent heartburn may raise the risk of pneumonia, reports a new review of studies looking at acid-suppressing drugs such as Losec and Tagamet. However, some of the best studies in the review found no increase in risk, making these findings less certain.

What do we know already?

For people who suffer from frequent heartburn (gastro-oesophageal reflux disease, or GORD), acid-suppressing medicines can work wonders. These drugs reduce the amount of acid that the stomach makes, so there's less to cause uncomfortable burning in your chest, neck, or throat.

There are two main types of acid-suppressing drugs: proton-pump inhibitors (PPIs), such as omeprazole (Losec) and esomeprazole (Nexium); and H2 blockers, such as cimetidine (Tagamet) and ranitidine (Zantac). Many people take these drugs for years to control their heartburn, with few (if any) noticeable side effects.

But recent research has raised the possibility of hitherto unrecognised adverse effects. For example, some studies have found that these drugs may inhibit the body's absorption of calcium, leading to weakened bones. And others have suggested that they may raise the risk of respiratory tract infections, including pneumonia.

The link with pneumonia isn't as far-fetched as it might sound. By lowering acidity in the stomach, these drugs may encourage bacteria to grow in the stomach and oesophagus. The bacteria might then get into the lungs, causing pneumonia.

To learn more, researchers have now gathered the best studies looking at acid-suppressing drugs and pneumonia. They pooled the results of these studies to see what conclusions they could draw from this larger body of research.

What does the new study say?

Overall, people taking acid-suppressing drugs were between 22 percent and 27 percent more likely to get pneumonia than people not taking these treatments. The researchers estimated that for every 200 people taking one of these drugs, one extra person would develop pneumonia.

They also found that the risk of pneumonia seemed to rise with higher doses. And the risk was highest when people first started taking these drugs.

How reliable are the findings?

This was a thorough review of the research that included 31 studies with thousands of people.

However, many of the studies were different in design and focus. For example, some looked at people who developed pneumonia in hospital, while others focused on people outside of hospital. Such differences make it difficult to reliably pool the studies' findings.

The review also included two different types of studies. Eight were observational trials, which are useful for spotting trends but can't prove cause and effect. The remaining 23 were randomised controlled trials (RCTs), which are the best type of study for finding out the effects of a treatment. When the researchers looked only at the RCTs, they found that the best of these studies reported no increase in risk. This makes the review's overall findings less reliable. More good-quality studies will need to explore this.