Would you drive 500 miles? Geospatial barriers to accessing deep brain stimulation clinical trials in the United States

Introduction: Deep brain stimulation (DBS) is a standard treatment for patients with various movement disorders, yet several studies have illustrated significant disparities in access to DBS across age, sex, and race. The aim of this study is to further investigate geospatial disparities in access to DBS clinical trials.

Methods: Data on median household income, diversity, and population were collected using the census.gov application program interface (API). Information on DBS clinical trial hospital locations was collected using the clinicaltrials.gov API. The distance between each census-defined ZIP Code Tabulation Area (ZCTA) and the nearest clinical trial site was computed. A population-weighted linear regression was utilized to examine the relationship between median household income and distance to the nearest clinical trial site.

Results: Over 25% of the entire United States population resides over 66 miles from the nearest center that has offered DBS as a clinical trial therapy. Twelve states had no clinical trials of DBS, including Alaska and Hawaii. Individuals residing further away from these clinical trial locations tended to have lower median income per ZCTA (p < 0.001). Non-white ZCTAs were closer to clinical trial sites (weighted z-test p< 0.001).

Conclusion : There is a critical need to expand access to DBS across the United States. The fact that non-white patients also reside closer to these trials than white individuals emphasizes further need to expand recruitment of diverse minorities into DBS trials. This could be accomplished through assessment and reduction of barriers to care, as well as development of tools to help patients efficiently find nearby, appropriate trials for their treatments.