How Our Web Searches Could Expose Drug Side Effects

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Researchers looking for previously undiscovered drug side effects are turning to web searches for answers.

When drugs are approved by the Food and Drug Administration (FDA), they are vetted for potential side effects, and drug makers are required to divulge these on their products labels. But not all side effects emerge in the short term studies that manufacturers conduct, so many only come to light when hundreds of thousands, and even millions of people start using a medication. And what better way, a group of researchers from theStanfordUniversity School of Medicine and Microsoft Research decided, to suss out some of these unexpected side effects than to turn to where people are most likely to report, share and ask about them the internet.

The researchers combed through a year of web search history from 6 million Internet user volunteers. Usingautomatedtools, the scientists were able to to mine anonymous data from 82 million drug-symptom andconditionsearchers made by the participants who agreed to let the users install a Microsoft plug-in to monitor their history.

The team was rewarded with a previously unreported interaction between two commonly prescribed drugs paroxetine (Paxil), an anti-depressant, and pravastatin (Pravachol), a statin that lowers cholesterol. About 5% of the people who searched for paroxetine also searched for a descriptor of hyperglycemia, or high blood sugar, which can trigger symptoms of blurry vision and dehydration. Less than 4% of people searching for pravastatin also searched for hyperglycemia symptoms. However, among those who searched for both drugswhich suggested they were taking both10% typed in hyperglycemia-related searches. That hinted that users of both medications were experiencing a drug-drug interaction that previous studies had not identified, since drug approvals dont include exhaustive studies of every potential combination of drugs that patients may take.

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But the web searches could serve as an early harbinger of potential problems when certain drugs are combined, as well as reveal new side effects of individual medications that did not emerge during drug development. While the FDA currently tracks this information, as part of its Adverse Event Reporting System, the system relies on voluntary reports from doctors,pharmacists, patients and drug companies, and these reports often lag behind initial reports which in many cases need immediate medical attention. (After mining reports sent in to the FDA, the study authors discovered hyperglycemia was aside effect of the joint use ofparoxetine and pravastatin, confirming their search-based findings.)

To further validate their results, the research team also studied searchers surrounding 31 drug interactions known to cause hyperglycemia, and 31 safe drug interactions. They did find more hyperglycemia-related searches for people using the drugs known to cause problems, but also a high rate of hyperglycemia searches among patients using drugs with no known related side effects. The scientists believe that in order to decrease the amount of false-positive results, they need to combine data from other sources such as social media, medical records and patient support forums.

The idea of exploiting the vast amount of information embedded in internet searches has already been used in improve flu tracking. The Centers for Disease Control (CDC) has created aFluView Influenza-Like Illness Activity app that showsgeographicflu-like activity and trends based on information reported to the agency from health care providers. Google Flu Trends uses search terms the search engine has determined to be indicators of flu activity, such as fever, influenza and flu, and aggregates that search data to estimate flu activity by state. Similarly, the healthcare product companyHelp Remedieslaunched its lighthearted Facebook app called Help I Have The Flu, which scans through users Facebook accounts to identify which of their friends is most likely to give them the flu.

TIME covered the app during the peak of flu-season:

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How Our Web Searches Could Expose Drug Side Effects