Can We Just Check Everything? Why More Testing Is Not Always Better
In an era of incredible technological progress, it is tempting to believe that more data always leads to better health. However, in medicine, more testing is not always beneficial. While it might seem logical that a hundred tests would provide a hundred clues, the reality is more complex.
There is actually some math that helps to explain why in some cases ordering more tests could mean a worse outcome. No test is 100% perfect Although many tests are accurate greater than 95%, even a test that could predict with 98% accuracy still has a 2% chance of getting it wrong.
In general, there are two types of tests your doctor may order:
A screening test
A diagnostic test
Screening tests typically have a lower threshold, which means higher sensitivity. The point of screening tests is to test a lot of people who don't have clues about an illness. Separate those who test positive from those who test negative so the positive results can be followed up with a diagnostic test. Science is always working to improve the precision of screening tests so that people who test positive are likely to actually have the illness being tested for and that anyone who tests negative is truly negative. The risk then of screening tests is that a person who doesn’t actually have a disease may test positive. Remember, there's that 2% chance that it might happen and that’s with a screening test that is 98% sensitive. Two percent may not seem like a lot and it isn't, but remember that multiple doctors are ordering these tests multiple times a day, multiple days a week, multiple weeks a year. 2% of 10,000 people still means 200 people who got worried because they got a false positive. Oftentimes the diagnostic test that is done after a screening test is invasive or costly. Now picture 200 people in a town getting a costly or invasive test just because of one false test result. The harm this can do quickly adds up.
After a doctor gathers up enough information by talking to their patients, they can use their expertise in medicine to order targeted tests instead of fishing for answers. When specific tests are ordered for specific patients, they can paint a much different picture that is far more accurate and lead to better decision-making.
Whenever a doctor is ordering testing, it can be easy to lie back and let them order as many tests as possible. You should really ask yourself:
Why am I getting tested for this?
What does a positive or a negative test tell you?
What will we do in the case of a positive or negative test result for each test that is ordered?
Wasting time on a false positive or the unnecessary worry or potential harm that a false positive may produce is avoidable.
Dr. Sharma is a board-certified family medicine physician and the founder of HealthWinds, a virtual-first family medicine practice serving DuPage County and the surrounding Chicago suburbs. He brings over 15 years of family medicine experience with Duly Health and Care and Loyola Medicine's MacNeal Hospital, among others. He sees patients ages five and up, with longer visits and direct access built around a membership model rather than insurance.
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