A New Metric to Identify—and Prevent—Pharmacy Deserts

Local pharmacies fill more than 90% of prescriptions in the United States, making them essential for much of the population. They’re also key providers of vaccines and services such as medication management.

Much like food deserts—areas where people lack adequate access to affordable, healthy food—pharmacy deserts have too few pharmacies to support the population, and they pose a threat to medication access and public health.

In a study published in JAMA Network Open, Yale researchers developed a way to identify pharmacy deserts—and communities at risk of becoming pharmacy deserts—based on travel time. Their approach accommodates regional differences in what’s considered a reasonable amount of travel—rural residents may be used to longer travel times than city-dwellers, for instance—and by distinguishing areas at risk, it points to communities where additional resources could prevent a pharmacy desert from forming.

“Pharmacies are so much more than places to get prescription medications. They’re frontline community health resources,” says Walter Mathis, MD, assistant professor of psychiatry at Yale School of Medicine and senior author of the study. “And while there are some existing definitions of pharmacy deserts, we thought there was room for improvement. We wanted to develop a robust definition that was relevant on a national scale.”

The researchers first collected location information for all of the pharmacies in the United States. They then developed travel time thresholds for each U.S. census tract. “We really felt like travel time, as opposed to distance, which previous definitions of pharmacy deserts have relied on, was a more important metric, as that’s how most of us make decisions about travel day-to-day,” says Mathis.

Supermarkets are among the most common resources for a given area. So travel time thresholds were determined by the minimum amount of time it would take for 80% of a community’s population to get to a supermarket. If there were no pharmacies within that travel time, then a census tract was considered a pharmacy desert.

Among the 323.5 million people living in the United States at the time of the study, 17.7% lived in a pharmacy desert, the researchers found. And nearly 9% of people lived in an area served by a single pharmacy, which the researchers have dubbed “keystone pharmacies.”

Within 18 states, more than 20% of the population lived in pharmacy deserts, and in five—New Hampshire, South Dakota, West Virginia, Maine, and Vermont—that number rose to more than 25%.

Further, the most rural settings were disproportionately reliant on keystone pharmacies, and independently owned pharmacies were more likely than chains to serve as keystones.

Opening a new pharmacy requires substantial investment, but supporting a keystone pharmacy could be a more affordable, less resource-intensive option for communities. Therefore, directing financial support toward keystone pharmacies is one way that city, state, and federal government programs could prevent communities from becoming pharmacy deserts, say the researchers.

This could be particularly important for some regions where a single pharmacy serves as a keystone for multiple census tracts. For instance, a pharmacy in Oxnard, California, sits in the middle of several census tracts and serves as the keystone pharmacy for seven of them, possibly serving more than 34,000 people. And the researchers identified several pharmacies that were serving as the only one available to multiple neighborhoods.

“These keystone pharmacies—almost heroic in that if they were to go away, a neighborhood or neighborhoods would collapse into a dramatically underserved area—are really special cases,” says Mathis. “Subsidizing them through grants or changing how they’re reimbursed by insurance are a few options that could keep these essential pharmacies running. It comes down to helping them remain economically viable.”

Because food deserts also exist in the United States, calculating reasonable travel thresholds through supermarket access could misrepresent pharmacy access in areas where food resources are inadequate, say the researchers. So context will be important when considering how to best target at-risk populations.

In that regard, the researchers have begun sharing their data with organizations in areas relying on keystone pharmacies.

“Hopefully, this will lead to locally generated ideas about how to support keystone pharmacies, augmenting smart new policies at the state and federal level,” says Mathis.