RENEE MONTAGNE, HOST:
In this era of big data, electronic medical records are a rapidly growing source for researchers, much like companies mine big data for ways to target ads. In the case of scientists, they're mining big data for the unsuspected side effects of drugs. One study has found a link between common heartburn medications and the risk of heart attack. NPR's Richard Harris reports.
RICHARD HARRIS, BYLINE: It's hardly a surprise that Stanford University, in the heart of Silicon Valley, would be home to people like Nigham Shah, an assistant professor of medicine and biomedical informatics.
NIGHAM SHAH: So we were analyzing electronic medical records and asking the question that people who take certain drugs - on average, do they have a higher rate of occurrence of certain kinds of adverse events?
HARRIS: Shah and his colleagues had access to millions of medical records - no names attached - from Stanford and a private outfit. And they decided to turn their attention to a widely used class of heartburn medicine called PPIs. That includes Prilosec, Prevacid and Nexium. Some laboratory research suggested that these drugs could affect heart tissue, so the researchers wanted to see if people who took these drugs were at a higher risk of getting heart attacks. They report in the journal PLOS One that they did indeed find a modest correlation.
SHAH: The increase in risk is about 16 to 20 percent, depending on the particular drug involved.
HARRIS: Assuming that the risk is spread evenly throughout the population, someone with a low risk of heart attack doesn't have much to worry about.
SHAH: So if your risk of a cardiovascular event or a heart attack is, say, 1 in 1 million, now it is 1.2 in 1 million.
HARRIS: Shah is more concerned about people who have a higher risk of heart attack. And considering that millions of people take these medications, even a low added risk for an individual can add up when you consider the whole population.
SHAH: I wouldn't want the public to panic and say we should stop taking these drugs. What I would rather want them is to have a conversation with their physician and ask, what is your baseline risk? And if your baseline risk is high, then maybe you want to take something else.
HARRIS: Or if your doctor happens to be drug-safety researcher David Juurlink at the University of Toronto, he'd say don't worry about this.
DAVID JUURLINK: The problem is that it's very easy to do studies of this sort that lead to conclusions that can be misleading. I know because I've done that; I've done it myself.
HARRIS: Dr. Juurlink has studied these PPI drugs and also found that people who take them are somewhat more likely to have a heart attack. But a correlation doesn't say anything directly about cause and effect. He has looked at all the factors that make someone more likely to be taking these drugs in the first place.
JUURLINK: Having a bad diet, drinking too much alcohol, smoking and all kinds of other things that might lead people to be on a PPI - I think it's much more likely that those things are the real reason for this association.
HARRIS: Juurlink says these heartburn drugs have been studied directly in people with a high risk of heart attack, and they did not appear to increase that risk. In case you're wondering, he says he doesn't take funding from drug companies. And he notes that PPI's are not risk-free - they can occasionally cause kidney problems, and they've been linked to osteoporosis, Vitamin B12 deficiency and low magnesium levels. Finally, Juurlink says research groups like the one at Stanford should keep mining their data to look for side effects, especially for drugs like this that are used by many millions of people.
JUURLINK: Drugs are brought to market because of randomized trials, typically a few thousand patients. And then they get used in patients who are very, very different from the patients in randomized trials. They get used in sicker patients. They get used for longer durations of time and at different doses, so it's really important that studies like this get done.
HARRIS: The challenge is that results from big data aren't always easy to interpret. Richard Harris, NPR News.
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