From the "protective association between walkable neighborhoods and depression in older adults" to "associations between the built environment and levels of obesity," studies have shown the importance of patients' locations. "Because we spend 100 percent of our time somewhere, it is reasonable to expect that place matters when it comes to our health," he wrote.

Whether it's climate or crime, outside influences on a person's environment can affect his actual wellness – but smart use of GIS and EHRs in tandem can help target care interventions to those who need it most.

"Neighborhood characteristics such as safety, pollution, and availability of fresh foods can have substantial impacts on the health of individuals," write Christopher L. Simpson and Laurie L. Novak in a 2013 AMIA study titled, "Place Matters: The problems and possibilities of spatial data in electronic health records."

Since EHRs have patients' addresses, those "can be rapidly geocoded to produce computational data elements that, when linked to referential data such as crime rates, climate information, pollution/air quality and neighborhood walkability scores, can produce actionable alerts, reminders and other events for clinical decision support, care coordination and outreach," write Simpson and Novak.

For example, they write, integration of GIS with the EHR would give clinicians data about chronic disease patients who "may have experienced disruption from a natural disaster, and provide a basis for outreach and support for affected individuals."

Sara L. McLafferty is the department head and a professor of geography and geographic information science at the University of Illinois at Urbana-Champaign. She's been at the forefront of GIS and geospatial analysis for years, keenly interested in how the places where we live, work and interact affect our well-being."

For instance one of her studies on the geography of health, funded by the American Cancer Society, looks at how placed-based inequalities, with regard to things such as access to health services, impact prostate and colorectal cancer outcomes in Chicago.

"I'm interested in health disparities and how those are related to the kinds of neighborhoods and environments that people live in," says McLafferty. "If you live in an area that has a lot of hazardous waste sites, high crime rates and few physicians nearby, your health outcomes might be much worse than somebody who lives in a more advantaged neighborhood." GIS first made an impact on healthcare back in the late '80s, she says, when the systems became more accessible to people. "Desktop systems for GIS were first developed, and the data we need to go into GIS became more readily available," she says. 

In the decades since, GIS has "definitely changed a lot," says McLafferty. "For one, we can handle much larger data sets. Also, you have data sets that are, in some cases, real-time data: tweets about flu, or things like that, that are coming in real-time – we can analyze them on the fly as they happen."