AIR Louisville / Propeller Health

Asthma and chronic obstructive pulmonary disease (COPD) can be pervasive, impairing, expensive, and even life-threatening, especially when patients do not receive proper treatment. In the United States asthma is a prevalent condition - 7.6% of people over 18 years of age have it and 13.6 % have had it at some point.1 Apart from the health implications, these conditions cost the US economy over $80B per year, according to research published in the Annals of the American Thoracic Society.2 The study found that, for the 15.4M people in the US with treated asthma, the associated out-of-pocket medical cost of asthma each year was $3,266 per person.  To address the serious challenge of asthma, the city of Louisville, Kentucky, a city where poor air quality makes it one of the “most challenging” in the US for people with asthma to live, turned to the collective intelligence of its residents to get more timely and objective data of where and when asthma is occurring.3

A key problem in effective and rapid treatment -- and prevention -- is accurate and complete information about the onset of an incident. Doctors are reliant on patients’ ability to recall factors surrounding an incident and patients may not be aware of contributing environmental factors. At a health research and policy level, the typical method for studying asthma outbreaks in specific locations is to conduct inefficient personal interviews with each patient, which could take months or even years. 

Confronted with this problem in Louisville was Ted Smith, the Louisville Metro Government’s Chief of Civic Innovation. Smith says he knew that Louisville:

...had a very high rate of breathing disorders compared to the national average. I spent enough time with companies having a hard time relocating to Louisville because of this, that when Mayor Fischer asked me what was on my innovation agenda, I knew this had to be part of it.4

Smith saw an opportunity to “revolutionize” asthma treatment in collaboration with the digital health firm, Propeller Health (then a research project called Asthmapolis) and local partners.5 In 2012, they launched the Air Louisville pilot program to capture better data about asthma and COPD triggers so they could use the knowledge to inform better interventions. Support from the Robert Wood Johnson Foundation enabled participation in the program to be expanded to include hundreds more residents.

Figure 1: A Propeller Health inhaler fitted with sensors (Source: https://www.airlouisville.com/about.html)

The result?

In Air Louisville, 1,147 residents signed up to Propeller Health’s mobile app and were given inhalers fitted with sensors.

The sensors captured data on the location, date and time, and dosages of inhaler use.

Figure 2: Image of the asthma risk “heat map” (Source: https://www.airlouisville.com/results.html)

The platform combines this data with air quality and weather data to create a map of triggers for asthma and COPD incidents across the city. The app also enables patients to get reminders to self-medicate and other tips for managing their condition.

Using the map of asthma and COPD triggers, the Metro Government identified steps it could take to improve air quality. This included developing recommended routes that directed trucks away from at risk neighborhoods, planting more trees, and considering zoning policies that create buffer zones around schools and residential areas to minimise the effect of highways and industrial emissions. The Government also introduced a notification system to alert residents when poor air quality and weather conditions increased the risk of incidents.6 Ted Smith, now a Professor of Environmental Medicine at the University of Louisville, meets regularly with Metro Government staff to discuss further implementation of the recommendations. 

Over a period of 12 months, the Air Louisville program observed in participants enrolled in the project:7

• An average of 82% reduction in asthma rescue inhaler use
• 29% of uncontrolled participants gained control of their asthma
• On average, participants more than doubled their symptom-free days
• Participants slept better, with an average 19% increase in symptom-free nights.

Air Louisville data continues to be applied in other ways. It was used to show health improvements after two energy plants switched from coal to natural gas. It has also helped to launch a new project led by the University ofLouisville - Green Heart - a five-year clinical trial in which researchers are examining whether increasing green space in a neighborhood improves air quality and human health.

Adoption of Propeller Health’s technology has grown too. Propellor’s sensors and app are now used by more than 100,000 people in the US for managing asthma or COPD.8  As of 2017, Properllor’s technologies were deployed in more than 45 programs, some of which include large health systems such as Dignity Health.9 The Propeller mobile app also continues to evolve and now includes a feature that helps people to manage their prescriptions and find a local pharmacy.

How did it work?

Air Louisville began with a pilot study conducted by the Metro Government and Propeller Health (then-known as Asthmapolis) in 2012, with 300 inhaler sensors distributed to Louisville residents. This pilot helped to demonstrate that, contrary to popular belief, asthma triggers were not specific to where the participants lived but rather appeared all over the place due to different environmental factors.10

The pilot generated significant public interest, including from the Robert Wood Johnson Foundation, which supported Ted Smith and the Community Foundation of Louisville to create the Institute for Healthy Air, Water and Soil. A partnership involving the Institute, the Mayor’s office, Louisville Metro Government, Propellor, and a coalition of employers, healthcare providers and advocacy groups that helped to enroll participants in the program, then developed and launched the expanded version of Air Louisville.  A total of 1.2 million data points were collected, including 251,000 medication puffs, that were combined with over 5.4 million environmental data points to create the map of asthma and COPD triggers that informed the Louisville Metro Government’s responses.11

Propeller Health’s app and sensors gather and share data by:12

• Distributing inhalers fitted with sensors to asthma and COPD patients and signing patients up to the Propeller app to track inhaler usage
• Storing the data captured In a central cloud that enables it to be aggregated, sorted and shared back with patients, doctors, researchers and policy makers
• Using the app to share back with patients information about their inhaler use, including visualizations, reports, reminders and a forecast based on the environmental factors of a location on a given day
• Providing doctors access to a web portal where, with patient permission, they can monitor a patient’s progress, adherence to medication, and state of asthma control
• Sending alerts to a patient’s doctor when a patient misses controller use for four consecutive days or is at risk of an exacerbation of their condition.

Why It Worked

The success of Air Louisville can be attributed to:

1. Data sharing that enabled collective action: By combining existing data sources with new data collected by patients and sharing it in useful ways, Air Louisville helped to develop a trusted evidence base for targeted interventions by government and patients themselves.
2. Strategic partnerships: By partnering with Propeller Health the government gained access to an existing suite of digital health products while collaboration with employers, healthcare providers and advocacy groups built participation in the program as well as the legitimacy of it.
3. User focus: Propeller’s system accounted for the needs of patients who already confronted the challenge of managing a chronic condition and rather than assign patients more tasks, automated the data collection through the sensors and the app.
4. Technology: The advent of smartphones and cloud computing unlocked the potential of digital health generally, and in Air Louisville, was key to enabling resident participation and faster data collaboration at scale.
5. Addressing an agreed, high priority problem: There was consensus among key stakeholders that air quality and respiratory illness was a significant issue that needed to be addressed in Louisville.

Listen to the podcast episode with city planner Ted Smith here

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1. US Department of Health and Human Services, Summary Health Statistics: National Health Interview Survey, 2018, accessed February 16, 2020, https://ftp.cdc.gov/pub/Health_Statistics/NCHS/NHIS/SHS/2018_SHS_Table_A-2.pdf.

2. American Thoracic Society, “Asthma Costs the US Economy More than $80 Million Per Year,” January 12, 2018, https://www.thoracic.org/about/newsroom/press-releases/journal/2018/asthma-costs-the-us-economy-more-than-80-billion-per-year.php.

3. “About,” AIR Louisville, accessed February 16, 2020, https://www.airlouisville.com/about.html. 

4. Ted Smith (University of Louisville School of Medicine), interview, December 19, 2019.

5. Propeller Health was initially created as Asthmapolis in 2010

6. Gary J. Kurtzman, “A Breath of Fresh Air: An Oral History of Propeller Health,” Safeguard (blog), September 6, 2017, https://www.safeguard.com/2017/09/06/breath-fresh-air-oral-history-propeller-health/. 

7. “AIR Louisville Results Summary,” AIR Louisville, accessed February 16, 2020, https://www.airlouisville.com/results.html.

8. Arundhati Parmar, “Even After Successful Exit, Propeller CEO Is Far from Done,” Med City News, October 30, 2019, https://medcitynews.com/2019/10/even-after-successful-exit-propeller-ceo-is-far-from-done/?rf=1.

9. “Propeller Health,” Most Innovative Companies (web page), Fast Company, accessed February 16, 2020, https://www.fastcompany.com/company/propeller-health.

10. Ted Smith (University of Louisville School of Medicine), interview, December 19, 2019.

11. “AIR Louisville Results Summary,” AIR Louisville, accessed February 16, 2020, https://www.airlouisville.com/results.html. 

12. For Air Louisville the full Propellor app was used with the exception of sharing data with doctors