The Impact of a Place-Tailored Digital Health App Promoting Exercise Classes on African American Women’s Physical Activity and Obesity: Simulation Study
Authors: Powell-Wiley Tiffany M , Martinez Marie F , Tamura Kosuke , Neally Sam J , O'Shea Kelly J , Curlin Kaveri , Albarracin Yardley , Vijayakumar Nithya P , Morgan Matthew , Ortiz-Chaparro Erika , Bartsch Sarah M , Osei Baah Foster , Wedlock Patrick T , Ortiz-Whittingham Lola R , Scannell Sheryl , Potharaju Kameswari A , Randall Samuel , Solano Gonzales Mario , Domino Molly , Ranganath Kushi , Hertenstein Daniel , Syed Rafay , Weatherwax Colleen , Lee Bruce Y 
Published: August 2022

Background
The increasing prevalence of smartphone apps to help people find different services raises the question of whether apps to help people find physical activity (PA) locations would help better prevent and control having overweight or obesity.

Objective
The aim of this paper is to determine and quantify the potential impact of a digital health intervention for African American women prior to allocating financial resources toward implementation.

Methods
We developed our Virtual Population Obesity Prevention, agent-based model of Washington, DC, to simulate the impact of a place-tailored digital health app that provides information about free recreation center classes on PA, BMI, and overweight and obesity prevalence among African American women.

Results
When the app is introduced at the beginning of the simulation, with app engagement at 25% (eg, 25% [41,839/167,356] of women aware of the app; 25% [10,460/41,839] of those aware downloading the app; and 25% [2615/10,460] of those who download it receiving regular push notifications), and a 25% (25/100) baseline probability to exercise (eg, without the app), there are no statistically significant increases in PA levels or decreases in BMI or obesity prevalence over 5 years across the population. When 50% (83,678/167,356) of women are aware of the app; 58.23% (48,725/83,678) of those who are aware download it; and 55% (26,799/48,725) of those who download it receive regular push notifications, in line with existing studies on app usage, introducing the app on average increases PA and decreases weight or obesity prevalence, though the changes are not statistically significant. When app engagement increased to 75% (125,517/167,356) of women who were aware, 75% (94,138/125,517) of those who were aware downloading it, and 75% (70,603/94,138) of those who downloaded it opting into the app’s push notifications, there were statistically significant changes in PA participation, minutes of PA and obesity prevalence.

Conclusions
Our study shows that a digital health app that helps identify recreation center classes does not result in substantive population-wide health effects at lower levels of app engagement. For the app to result in statistically significant increases in PA and reductions in obesity prevalence over 5 years, there needs to be at least 75% (125,517/167,356) of women aware of the app, 75% (94,138/125,517) of those aware of the app download it, and 75% (70,603/94,138) of those who download it opt into push notifications. Nevertheless, the app cannot fully overcome lack of access to recreation centers; therefore, public health administrators as well as parks and recreation agencies might consider incorporating this type of technology into multilevel interventions that also target the built environment and other social determinants of health.