How iPhone Health Tracking Data Can Help Us Understand Asthma

Health data collected entirely from smartphones could help researchers study an unprecedented amount of evidence-based information about the nature of chronic diseases. And a new study of asthma patients shows that the data isn't just scalable, it's pretty reliable too.

Traditionally, finding and recruiting enough people to participate in clinical studies has been a challenge for medical researchers. But by using the Apple ResearchKit, launched in 2015, scientists at the Icahn School of Medicine at Mount Sinai in New York were able to develop an app for asthma that overcame those barriers. It allowed researchers to gain easier access to patients, without regard to their location.

The Asthma Health app measured patients' symptoms, triggers and medication adherence accurately. It also collected other useful data such as geolocation and air quality, helping researchers to correlate daily asthma symptoms to environmental factors. For example, the scientists were able to relate wildfires in Washington state to increased symptoms in some participants. Other triggers such as pollen and heat were also corroborated as expected.

The results rivaled the size and quality of existing asthma studies, such as the National Health Interview Survey conducted by the CDC, according to Pei Wang, a genomics professor at Mt. Sinai who co-authored the study.

Nearly 50,000 people downloaded the app, though researchers capped the study at 7,593 people who completed the consent process to enroll in the study. Once participants granted permission, the Asthma Health app could monitor their asthma inhaler use and connect to their electronic health records.

"We now have the ability to capture rich research data from thousands of individuals to better characterize 'real world' patterns of disease, wellness, and behavior," Eric Schadt, senior author on the paper, said in a statement. "This approach provides a more comprehensive and accurate view of our patients that was not feasible in the past."

However, the smartphone-based study has its limitations. The researchers admitted that people who voluntarily downloaded the app may not represent the those who suffer from asthma in the general population. There might be a bias toward those who have more severe forms of asthma, as well as higher-earning, college-educated iPhone users. For example, 87 percent of people earning more than $75,000 own smartphones compared to just 52 percent of people earning less than $30,000, according to a Pew Research survey.

And though the researchers assured participants that their personal health information was encrypted and compliant with the Health Insurance Portability and Accountability Act (HIPAA), data privacy is still a concern.

Despite these weaknesses, the findings point to a positive direction in thinking about how to use smartphone-generated health data, especially at a time when there are an estimated 3 billion users around the world.