The Web May Be Hazardous to Your HealthHow to figure out what's ailing you without becoming a cyberchondriac.
Posted Friday, Dec. 12, 2008, at 5:08 PM ET
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StumbleUponThis makes sense: Even though they're rare, serious conditions like ALS or brain tumors merit a lot of medical attention and, therefore, many articles on the Web. But human beings are easily confused into thinking that quantity represents likelihood. Psychologists call this the availability bias—if we hear about something a lot, we tend to think it's common. For instance, studies show that because newspapers cover deaths caused by accidents and homicide more often than they do deaths caused by disease or suicide, people erroneously believe that accidents and murders are a common way to die. In the same way, when you search for "headaches," you become entranced by the number of articles on brain tumors—and in the avalanche, you quickly forget that your headache is probably caused by something more mundane.
To escape this bias, you've got to become a smarter searcher. Doctors use a process known as differential diagnosis, in which they examine a patient to eliminate unlikely causes of disease. (If you want to know how this works, watch House.) The trouble is that finding the respective probabilities of certain diseases for different patients can be difficult online. If a 25-year-old woman experiences a sudden, sharp chest pain, she is most likely not having a heart attack; a doctor, knowing these facts, will dismiss that idea quickly and would try to find some muscular, gastrointestinal, or psychological condition causing her discomfort. (In one study, 25 percent of emergency room patients who experienced noncardiac chest pain were also diagnosed with a panic disorder.)
But Horvitz says that it took him a while to find the online statistics suggesting that heart attacks are uncommon in young people—and he's a medical doctor who knows where to look. If you experience chest pain and look to the Web for help, you'll see heart attacks displayed prominently. In their survey of Microsoft employees, White and Horvitz found that half of Web searchers took search rankings as a proxy for likelihood; if something was listed up high, they were more likely to assume it was what ailed them.
This suggests a way for search companies like Microsoft and Google to improve their health offerings, the researchers say. Search engines could detect when people are looking for symptoms of diseases and then switch to diagnostic mode. In this mode, the search engine would not only ask you to fill out symptoms but also things like risk factors (your age, sex, weight, and so forth). Then the search engine would display a list of Web results in order of the likelihood that the diseases mentioned in those articles might affect you. By acting in this manner, the search engine would be closer to what doctors call "decision support systems," sophisticated programs that doctors use to help in their diagnoses. Several studies show that these systems can be accurate in spotting even complex diseases like schizophrenia.
Until we get such a search engine, White and Horvitz's research suggests that you might be better off looking for information at dedicated medical sites like WebMD, the Mayo Clinic, or the health sections on MSN or Yahoo. Compared with articles found by searching the Web, pages found on dedicated health sites were far more likely to point toward innocuous—rather than grave—causes for certain symptoms, the researchers found. WebMD even has a "symptom checker" tool similar to the diagnostic search engine I describe above. You tell it your sex, age, and a few symptoms, as well as descriptions of what you're feeling (is your chest pain sharp, dull, stabbing?), and it lists the conditions you might have.
There's only one downside to the WebMD page: Most people don't go to WebMD when they're sick. According to the Pew study, two-thirds of people looking for health information go to a search engine first, not a dedicated medical site. That's why search engines need to build in diagnostics—something that works much like WebMD's symptom checker but that includes articles from all over the Web. True, such a site probably wouldn't cure every cyberchondriac. But it would make the Web a lot less scary.
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