In 2014, the Robert Wood Johnson Foundation committed to fund a first-of-its-kind study of asthma and air quality in Louisville, KY, in part because the organization wanted to see whether patient-generated data could influence public policy.
The study, which was also funded by the American Lung Association and several local foundations, involved providing hundreds of asthmatic Louisville residents with high-tech sensors for inhalers that track where and when they take their medications.
The results of the study, some of which were published earlier this month in a paper in the medical journal Health Affairs, represent a “strong example of the potential” for information collected by patients to lead to policy changes in areas like land development and zoning, says lead author Meredith Barrett. She’s vice president of research at Propeller Health, a Madison, WI-based startup that developed the inhaler sensors and complementary software used in the study.
Researchers enrolled 497 patients in the study, all of whom used an inhaler with one of Propeller’s sensors for 60 days or more. Together, they used their inhalers nearly 35,000 times during the course of the study.
Barrett and her co-authors write in the paper that on the whole, participants experienced measurable improvements in their health. Researchers observed a 78 percent decrease in patients’ inhaler use after 12 months among participants who shared sensor-collected data with investigators for a year or longer. The study data indicate that on average, patients experienced fewer problems breathing both during the day and at night after they began using Propeller’s sensors and software.
The sensors, which snap onto the tops of metered-dose inhalers, use GPS technology to record patients’ location and time of use, and transmit those data to their smartphones via a Bluetooth connection. Propeller develops mobile apps for Apple and Android devices that are designed to help people with respiratory disease better understand and manage their conditions.
Additionally, in the first week of the study, 62 percent of patients experienced “symptom-free days,” when they didn’t need their inhalers. After 12 months, the share of participants who experienced symptom-free days climbed to 90 percent, according to the Health Affairs paper.
Barrett says the results of the study show that the increasingly sophisticated methods for tracking inhaler use that companies like Propeller are developing put more information in the hands of patients and their healthcare providers. But what have also animated Barrett and other authors of the paper—a mix of Propeller employees and academic researchers—are some of the macro-level analyses they’ve been able to do with sensor data.
“I’m really excited by the potential that these type of data have, both to help individuals better understand their disease but also to enable us to better understand different trajectories of disease, different environmental sensitivities, and more effective ways to personalize treatment,” she says.
The paper’s authors write that they observed patients’ asthma symptoms were worse in areas with elevated levels of air pollutants and urban heat, a term that refers to increased temperatures due to human activity. “Tree planting is one intervention that could ameliorate both of these exposures by trapping and filtering air pollution and reducing urban heat,” they write.
Policies aimed at planting and preserving trees in areas with substandard air quality could help people there who have asthma breathe easier, Barrett says. For instance, Kentucky’s Jefferson County (where Louisville is) requires developers to replace 15 percent of the trees they remove when developing a parcel of land. The paper’s authors, working with local municipal leaders and others involved with the AIR Louisville program, suggest increasing the replacement requirement to 45 percent of removed trees.
Other policy recommendations in the paper include developing truck routes “that would direct diesel trucks away from sensitive populations living in neighborhoods with the highest asthma burden.”
The City of Louisville plans to merge the sensor data collected during the study with traffic data from the navigation app Waze, Barrett says. This could help traffic engineers when they plot future highway routes in and around the city, she adds.
AIR Louisville is also working to use algorithms developed by Propeller to send forecasts of asthma risk, based on local environmental conditions, to the smartphones of Louisville residents who have respiratory disease, Barrett says. That could help someone with asthma plan the best times to exercise outside, for example.
The city has already committed to making some of the changes recommended by leaders of the AIR Louisville program, including ones related to tree planting, Barrett says. But it may take months or even years for city leaders to decide whether to move forward with other recommendations.
“Digital health data collection occurs on such a different time scale than lasting policy change,” Barrett says.
Other cities that like Louisville have high asthma rates, such as Pittsburgh, Portland, OR, and Knoxville, TN, have met with leaders of AIR Louisville about addressing the issue through urban planning and other approaches.
“We’re at different points of conversation with those cities [and others] to launch similar [programs] there,” Barrett says. “If we really want to influence the national policy conversation, we need to have a nationally representative sample.”