Neighborhood demographics heavily influence how Americans choose their pharmacies

An estimated 15.8 million people in the United States live in pharmacy deserts. With limited access to healthcare services, like hospitals and pharmacies, these individuals are at risk of elevated mortality risk and higher rates of preventable disease progression. 

A new study, published in Risk Analysis, has found that individual pharmacy choices are driven not only by proximity but by the sociodemographic character of the neighborhoods where they are located. 

Researchers from California Polytechnic State University (Cal Poly) conducted a case study combining mobility data from mobile phone usage and pharmacy foot traffic patterns with demographic and socioeconomic census data to examine healthcare access in Los Angeles County, California. The authors applied discrete choice theory to model consumer preferences and analyze demand behaviors in a state where healthcare access remains an issue. 

This research also draws a sharp distinction in how we understand access to essential services from a data-driven perspective. Much of the existing literature has focused on potential access, describing the extent to which services are geographically proximate. In this research, we looked at people's realized access, showing their actual use of facilities." 

Daniel Hopkins, an industrial engineering student at Cal Poly

The study found that only 70% of residents visited a pharmacy within 5km of their residence, despite nearly 98% having one that close (assuming individuals visit the nearest pharmacy). Additionally, over a third of low-income residents visited pharmacies in low-income areas while less than 7% traveled to wealthier neighborhoods for care, demonstrating that human mobility patterns exhibit strong social similarities. 

"Geographic access is necessary but not sufficient," added Dr. Zhiyuan Wei, an assistant professor in the Department of Industrial and Manufacturing Engineering. "People are not just going to the nearest pharmacy. They are going to places that feel socially familiar to them, and that has real consequences for how we plan and allocate healthcare services." 

The findings carry particular urgency given the scale of the pharmacy access problem nationally. With millions of Americans living in pharmacy deserts, areas with restricted access to the pharmacies that provide essential medications, rapid diagnostics and basic health services. In California alone, nearly 2.5 million residents, or 6 percent of the population, live in pharmacy deserts, the highest total of any state. In LA County, roughly 25 percent of census tracts are classified as pharmacy deserts. 

The researchers say their data-driven model can support decision-making beyond pharmacies, including grocery stores and other essential services, and could be especially valuable for understanding how access patterns shift during natural disasters and other hazard events, when mobility constraints intensify.