Specifically, the researchers used automated software to identify searches for info on the Paxil antidepressant, the Pravachol cholesterol drug or both pills during 2010. And they found evidence that the combination of these drugs caused high blood sugar. The study was published in the Journal of the American Medical Informatics Association (here is the abstract).
Two years ago, the researchers had previously culled adverse events reported by physicians to the FDA and found the risk of developing hyperglycemia was greater than the risk of hyperglycemia from taking either drug individually. The latest study was designed to access a faster way of gaining such insights.
"Historically, it's been really hard to detect synergistic effects of drug combinations that aren't necessarily side effects of any of the drugs alone," Russ Altman, a Stanford University professor of bioengineering, of genetics and of medicine, and co-author of the study, says in a statement.
The researchers first identified individual searches for the drugs and the calculated the odds that people in each group would search for hyperglycemia — or almost 80 of its symptoms or descriptive terms, such as "high blood sugar," "blurry vision," "frequent urination" or "dehydration."
They found that, among people who searched for Paxil, which has the chemical name paroxetine, about 5 percent also searched for hyperglycemia or a related phrase. For Pravachol, or pravastatin, the rate was below 4 percent. But for those who searched for both drugs - suggesting they used both pills - the search rate was 10 percent.
To verify the accuracy of their analysis, they examined 31 drug-drug interactions already known to cause hyperglycemia, and 31 interactions known to be safe. Overall, the drugs with known interactions led to more search queries on hyperglycemia.
"But the results also suggested that around 12 percent of users searching for drug combinations known to have no interactions also had an unusually high rate of hyperglycemia searches, which would lead researchers down dead ends if they pursued them," according to the Stanford statement.
The researchers believe that combining search history data with other sources of information — such as social media, patient support forums and information from medical records and doctors - will improve the false-positive rate.
"I believe patients are telling us lots of things about drugs, and we need to figure out ways to listen," says Altman. "This is just one way of listening and one application."