When you apply for health insurance on the exchange, you’ve got to put in some basic information. Age, location, gender and income are some of the data points that the health exchange collects from applicants-- race and ethnicity are optional on the application. Taken together, these data points help paint a picture of who and where the exchange has successfully reached.

“The good news is we’re enrolling more and more people, and so the target population we have to reach is smaller, but harder to reach for various reasons or they would’ve been part of the group we’ve already covered,” says Carolyn Quattrocki, executive director of the Maryland Health Benefit Exchange.

Quattrocki says enrollment data is useful not just for knowing who is signing up, but knowing who is not signing up. That information lets exchange officials target outreach efforts.

If Spanish speakers aren’t signing up in appropriate numbers, for example, more Spanish radio ads could help. The Eastern shore and Western Maryland were underrepresented last year, so there were more health fairs in those regions this year. And, Quattrocki says, there’s one group that’s always hard to convince to get insured: Young invincibles – those young people who don’t typically use a lot of health care, and don’t bother to buy health insurance.

“We did reasonably well with the young demographic last time around, but they continue to be a group that’s harder to persuade that they need insurance and can benefit from it,” Quattrocki says.

Thursday is the last day to buy health insurance that starts in January through Maryland’s health exchange. The exchange will still be open after the midnight deadline, but the coverage won’t start until February.

Maryland is making a big dent in the ranks of the uninsured. About 460,000 people signed up for insurance through the exchange last year, though not all of them were previously uninsured. More than 105,000 signed up this year as of Tuesday, although that number includes some repeat customers. Going forward, the exchange will rely even more heavily on data to target the shrinking pool of people without insurance.

“That last ten percent is always the hardest to reach,” says Jonathan Weiner, a professor at  Johns Hopkins Bloomberg School of Public Health. “They’re people that are hard to reach, people that have some challenges, perhaps don’t trust government or don’t trust healthcare providers.”

Weiner says data is changing healthcare, beyond the first step of getting people insured. “Right now our main focus is getting someone an insurance card. I think in the future though the real benefit will be health insurance plans and health agencies using this data to improve the health of people who have an insurance card,” he says.

Weiner says data collected by Maryland’s health exchange can be combined with information from public health agencies, hospitals and health insurance companies to figure out how people are actually using health care. That, in combination with the huge expansion of electronic health records in doctors’ offices under the Affordable Care Act and the proliferation of wearable health devices like FitBits, has huge potential to encourage better health and prevention for patients, he says.

Still, data has limitations. “Data will not make you healthy,” Weiner says. “If it shows you’re an outlier with weight or an outlier with exercise or an outlier with nutrition, someone has to take an action.”

So going to the gym and eating your vegetables is still on you.

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