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Online Symptom Checkers: How Accurate Are They?


Computers are amazing. They can beat world-class chess champions. But they can’t yet replace your doctor. Case in point—online symptom checkers.

The checkers, free at sites such as WebMD, Mayo Clinic and the American Academy of Pediatrics and through free smartphone apps such as AskMD and iTriage, are powered by pretty sophisticated medical algorithms.

If you are like millions of other people, you may have turned to one of these to figure out what’s triggering a chronic cough or repeated headaches, a rash, insomnia or unexplained weight gain or loss.

These programs are easy to use—you just plug in one or more symptoms, the program asks you a few questions and then it suggests what condition or conditions you might have. The checkers make recommendations, too, such as what to do to feel better and whether to see your doctor—or head immediately to the ER. While symptom checkers may not explicitly promise to give you a diagnosis, it’s become increasingly common for people to turn to them to try to figure out what’s causing their symptoms.

A smarter approach: Don’t rely on these programs to help you figure out what’s wrong with you. While they may have some educational value, the latest research finds that they are not only unlikely to give you the most probable cause of your symptoms but also prone to putting people in a panic and sending them for urgent medical care when it is not needed. They do have a place, however—if you know the smart way to use them.


In the first study to compare the diagnostic accuracy of these online tools with the accuracy of live MDs, researchers at Harvard Medical School asked 234 doctors trained in internal medicine, family practice or pediatrics to evaluate 45 “clinical vignettes”—symptoms and medical histories of hypothetical patients—and give the most likely diagnosis plus two additional possibilities for each patient. The conditions ranged from common to uncommon, from minor to life-threatening—for example, canker sores to pulmonary embolism (a very dangerous blood clot in the lung).

Results: The white coats won by a mile. Computerized symptom checkers identified the most likely correct diagnosis only 34% of the time…doctors, 72% of the time. Counting all three suggested diagnoses, checkers included a correct diagnosis only 51% of the time—but docs included a correct diagnosis 84% of the time. (In case you were wondering, no particular symptom checker was better than the others.)

More findings from the study…

  • For the mildest diseases, the automated symptom checkers did a little better, nailing 40% of the cases on the first try. But docs nailed 65%.
  • For the most common diseases, checkers got 39% versus 70% for doctors.
  • For acute illnesses—the kind that really need immediate attention—checkers guessed right only 24% of the time…doctors, 79%. That’s a huge difference and could make a big impact on a patient’s life.
  • For the rarest diseases, checkers got it right only 28% of the time versus 76% for doctors.


It’s not that doctors have reached diagnostic perfection, either.  While they beat the technology tested in the Harvard study, they still failed to give the right diagnosis from three options in about 15% of the cases, which is consistent with previous estimates of human misdiagnoses.

A goal of the study was to see whether computers could help doctors get better at diagnosis. One way to improve is for the programs to build in data from epidemiology—real-time information about the frequency of illness in the community. After all, if you see your doctor with digestive ills and he/she knows that there’s a GI infection going around town, that may help target the diagnosis. Ideally, as the checkers improve, they’ll help doctors improve their diagnostic skills—and help the public, too.

In the meantime, patients should exercise extreme caution in using these programs. They can play a role if they help you educate yourself about possible causes of your symptoms—and that prompts a discussion with your doctor. That is, use them to educate yourself so that you can ask smart questions. But for a real diagnosis, there’s no substitute for a real doctor.

Source: Source: Ateev Mehrotra, MD, MPH, associate professor of health-care policy and medicine, Harvard Medical School, and hospitalist, Beth Israel Deaconess Medical Center, both in Boston. He was lead investigator of “Comparison of Physician and Computer Diagnostic Accuracy,” a study published in JAMA Internal Medicine. Date: March 1, 2017 Publication: Bottom Line Health
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