This week Google unveiled its new symptom cards, which will pop to the top of your search results the next time you try to search for your various ailments. Currently only on the Apple or Android Google apps, this feature will eventually be available through web browser searches too. Google developed its symptom cards with the help of doctors at Harvard medical school and the Mayo Clinic.
Other symptom checkers, perhaps driven by medico-legal concerns, feed the fears of hypochondriacs. There’s no vetting process. They list scary and rare diagnoses alongside the most probable. The advice they give is conservative, recommending most patients seek care even when a little TLC at home would have done the trick. They’re also not very accurate. A study of 23 symptom checkers found they came up with the right diagnosis first only a third of the time.
Much to my relief, the Google symptom checker focuses on what’s most common. So maybe now I’ll have fewer patients asking for unnecessary scans or to be tested for heavy metal poisoning or food allergies or Lyme disease. A search for “runny nose and cough” ranks the common cold at the top. Google’s symptom card recommends taking over-the-counter remedies, not antibiotics.
Every medical student is taught “when you hear hoof beats, think of horses not zebras” – in other words, don’t favor an exotic explanation over a more likely one. Still, every once in a while, it’s a zebra.
Sometimes it’s a seemingly trivial or unrelated detail that helps us uncover the diagnosis. But patients and doctors don’t rank symptoms or describe them the same way. Patients emphasize what’s most painful or bothersome. We focus on what makes for a good clue and we look for red flags.
You might have disabling low back pain. Google’s symptom card tells us you likely have a strain or sprain and can be treated with physical therapy and pain relievers. That’s great advice for most people, but maybe you also have a fever or recently became incontinent of urine. You might not realize these symptoms could be related and point to something more serious like cancer or an infection in your spine. You might tell me you have chest pain, but having chest pain when you’re doing yard work means something different to me than having chest pain when you take a deep breath.
Doctors’ pattern recognition is based on more than a symptom or two. But enter three or more symptoms – such as constipation, blood in stool and weight loss, which would be concerning for colon cancer – and Google’s symptom checker stutters.
We also think in terms of demographics (eg age, sex, race and ethnicity), socioeconomics and geography. We want to know if you smoke or drink or use drugs, if you’ve traveled and where, and if you’ve been around anyone sick or have a new sexual partner. One medical condition could put you at risk for another, and some medical conditions run together.
Let’s say you have a fever. Google tells us you might have the flu. But if you just came back from a backpacking trip around southeast Asia, you could have malaria or dengue. If you also have swollen glands, Google says you could have mono, the flu, a common cold, Strep throat or tonsillitis. But if you told me you’d recently had unprotected sex after a first date, I’d worry you might have HIV.
But Google may have some advantages over us. Patients may be more honest with computers than their doctors and more willing to share embarrassing details. Though patients may not think a computer can harbor prejudice, computers suffer from the foibles of their human creators.
Google’s symptom checker won’t replace doctors anytime soon. But it’s important to remember that Google is in the business of collecting, using and selling information. So, people who care about public health shouldn’t just ask whether Google can make an accurate diagnosis one day – but at what cost that development might come.