Pharmacy deserts: More than where pharmacies are

In the United States, geographic access is a major driver of health care disparities. Studies have shown that pharmacy deserts are prevalent in the United States, even in major metropolitan areas. However, one limitation often cited by these studies is the use of distance rather than travel time to define pharmacy deserts.

The aim of this study was to assess pharmacy deserts using travel time and to provide a more holistic approach by incorporating analysis of private vehicles and public transportation.

Pharmacy details were collected from the National Provider Identifier database and neighborhood characteristics from collected census data for the four largest U.S. cities. Pharmacy access was evaluated using open-source routing engines. We determined neighborhoods in pharmacy deserts using both distance and travel time analyses. Sensitivity analysis was performed to determine changes to pharmacy deserts based on small changes in travel time.

Of 4654 neighborhoods identified in the four cities of interest, 670 (14.4%) neighborhoods were in pharmacy deserts based on distance. Despite accounting for 28.9% of all neighborhoods, predominantly white neighborhoods only accounted for 4.3% of pharmacy deserts. When evaluating pharmacy deserts by car and public transportation, predominantly white neighborhoods accounted for 2.3% and 1.7% of total pharmacy deserts, respectively. Finally, by reducing travel time from 15 minutes to 10 minutes, pharmacy deserts by car and public transportation increased by 105% and 199%, respectively. All but 3 of the new pharmacy deserts found in the sensitivity analysis were found in nonpredominantly white neighborhoods.

Using travel time and incorporating modes of transportation, we found that disparities in pharmacy access are more than just where pharmacies are located geographically. There are additional layers of disparities, such as access to public transportation, that need to be addressed to reduce the number of pharmacy deserts.