Geographic Access Disparities of Clinical Trials in Neovascular Age-Related Macular Degeneration in the United States

To identify geographic and socioeconomic variables predictive of residential proximity to neovascular age-related macular degeneration (nAMD) clinical trial locations.

Design: Retrospective, cross-sectional study.

Methods: Census tract-level data from public datasets and trial-level data from ClinicalTrials.gov were analyzed. We calculated the driving distance (>60 miles) and time (>60 minutes) from the population-weighted US census tract centroid to the nearest clinical trial site.

Results: We identified 42 trials studying nAMD across 829 unique clinical trial sites in the United States. In a multivariable model, driving distance >60 miles had a significant association with rural location (adjusted odds ratio [aOR] 5.54; 95% confidence interval [CI] 3.86-7.96, P < .0001) and with Midwest (aOR 2.30; 95% CI 1.21-4.38, P = .01) and South (aOR 2.43; 95% CI 1.21-4.91, P = .01) as compared to the Northeast region, and with some college or an associate's degree, as compared to a bachelor's degree (aOR 1.02; 95% CI 1.01-1.04, P = .0007, and aOR 1.05; 95% CI 1.00-1.10, P = .04, respectively). Lower odds of traveling >60 miles to the nearest nAMD trial site were associated with census tracts with a higher percentage of blacks (aOR 0.98; 95% CI 0.97-0.99, P < .0001), Hispanics (aOR 0.97; 95% CI 0.95-0.99, P = .002), and Asians (aOR 0.90; 95% CI 0.88-0.93, P < .0001), as compared to whites, and with a lower percentage of the population <200% of the federal poverty level. Similar predictors were found in time traveled >60 minutes.

Conclusions: There are geographic access disparities of clinical trial sites for nAMD in the United States.