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How to Get More People to Take HIV Tests

Manipulating people with social science, for good.
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(Photo: Wheeler Cowperthwaite/Flickr)

(Photo: Wheeler Cowperthwaite/Flickr)

When you started your job, did your company automatically enroll you in a retirement plan? If it did, your human resources department was using social science to manipulate you—for good. Over the past couple of decades, several studies have found that when companies give new workers 401(k)s by default, employees are much more likely to participate in the plans than if they have to actively sign up. That's the power of "opt-out" versus "opt-in." Using opt out, you can steer people toward services that, though beneficial, many people might still neglect to undertake, out of sheer inertia.

With that in mind, in 2006 the Centers for Disease Control and Prevention recommended clinics offer HIV tests using an "opt-out" scheme. Now, a new study suggests the recommendation likely does increase the number of folks who get tested. Apparently the opt-out effect works for HIV diagnoses much the same as it does for retirement funds. At the same time, the new findings bring up fresh questions about balancing public health with individuals' right to freely choose the medical care they want.

Less than one-third of opt-in patients took an HIV test, compared to about half of the neutral patients and two-thirds of opt-out patients.

The study included 4,800 people who visited an emergency room in an anonymous, urban hospital between 2011 and 2013. All of the patients were randomly offered an HIV test in one of three ways: opt in ("Would you like a test today?"), opt out ("You will be tested unless you decline"), and neutral ("You can let me, your nurse, or your doctor know if you'd like a test today"). The results were striking. Less than one-third of opt-in patients took an HIV test, compared to about half of the neutral patients and two-thirds of opt-out patients. The effect held true across people of different sexes, races, education levels, and sexual orientations. The opt-out effect showed up strongly among people with a higher risk of HIV infection, such as injection-drug users and those with many sexual partners.

For public health officials, that's a win. Agencies like the CDC want lots of people to get tested, and no wonder: It's estimated 20 percent of HIV-positive Americans haven't been diagnosed. If doctors can catch those folks, they can offer treatment and reduce the spread of the virus.

The research team that conducted the study, however, noted using the opt-out effect in this way may not be fair to patients. Because so many more of the "opt-out" patients got tested, compared to those who were offered the test neutrally, some of the opt-out folks might have wanted to decline testing, but were afraid to speak up, the researchers, a team from the University of California–San Francisco, write in their paper, published yesterday in the journal BMJ.

With such solid results, it's hard to imagine public-health agencies choosing not to wield the opt-out effect. But the neutral approach best gets at people's true wishes, the UCSF team argues. This will be an important debate for doctors and patients to have into the future, for HIV testing and other medical tests too.


Quick Studies is an award-winning series that sheds light on new research and discoveries that change the way we look at the world.