Whether you want to assess your hormone levels, liver function or heart health, find out why you’re tired all the time or get a general wellness profile, increasing numbers of at-home self-testing kits are promising to help. Often, these are marketed as a way of taking control of your personal health. But experts warn that consumers are at risk of buying products that may do more harm than good.
Patti Shih, a sociologist at the University of Wollongong, has studied the rise and rise of self-testing and recently co-authored a paper in The Lancet that examined its pitfalls. “There’s been an explosion in the variety and amounts of these tests,” says Shih. “Many consumers are using them because they’re accessible, whereas it can take weeks to get a doctor’s appointment, then they might be denied the test they want.
“It’s difficult to get a sense of the exact demographic buying them, but what we do know is that the market is big.”
The Covid-19 pandemic familiarised us with self-testing as we got used to taking rapid antigen tests at home. Some of the other direct-to-consumer tests available are similar, in that you conduct the whole thing at home and get fast results. With others, the sample is sent to a laboratory.
Although some tests might be accurate and useful, Shih says there are a range of problems associated with using them, such as the lack of medical guidance. A doctor will look at a patient’s medical history and assess symptoms before deciding on the appropriate method of diagnosis. They will also follow up and interpret any results. With self-testing, all of that may be missing.
“If you give a good quality test to the wrong patient, it’s still the wrong test,” she says. “There’s the potential of false positives or false negatives. And then, once you have the results, what do you do with them?”
Some self-testing isn’t backed by science: for example, hair-testing for food intolerances. Others might give an accurate result but still won’t be particularly helpful. Hormone self-testing is marketed at women in peri-menopause, but since hormones rise and fall, the test can provide a snapshot of only a moment in time and isn’t a good method of diagnosis.
Other tests are marketed as wellness checks and aimed at people who are very health conscious. Shih has been studying YouTube influencers who promote tests for testosterone levels and food sensitivity.
“These aren’t superstar A-listers, they’re everyday people who have a YouTube channel. Usually, they’ll offer a promotion code, and they might earn a few dollars per test that their followers order.”
Her concerns include misleading information, the risk of over-testing, distress associated with abnormal results that are not clinically important, and that self-testing may lead to unnecessary use of non-evidence-based supplements and treatments that carry health risks.
Perhaps most concerning are the cancer self-tests being marketed and sold in the US. These claim to detect over 50 types of cancer before symptoms have occurred. But Shih and her colleagues caution there is a high risk of false positives, and when they are accurate, these tests tend to detect cancer at an advanced stage, so lead to earlier but not more successful treatment.
Multicancer tests, which measure various substances such as abnormal DNA, are still in the development stage, says Shih. “There are a lot of promises – it’s like a shiny new gadget. But using one is a bit like using a driverless car before it’s been proven it works.”
Largely thanks to advances in diagnostic technology and digital health, in the US alone, sales of direct-to-consumer tests surged from $15 million in 2010 to $1.15 billion in 2022. Although it is difficult to predict how the market will grow, self-testing isn’t likely to go away, so experts are calling for better regulation and for patients to have clearer information about when testing is recommended and when it is not.
“There’s a place for these tests,” says Shih. “But we need to make sure they’re accurate and that people have clinical support around them.”
