Geographic Access Disparities to Clinical Trials in Diabetic Eye Disease in the United States

Purpose: To identify geographic and socioeconomic variables predictive of residential proximity to diabetic eye disease clinical trial locations.Design: Cross-sectional, retrospective study.Participants: De-identified census tract-level data from public datasets and trial-level data from ClinicalTrails.gov.Methods: Using public data from ClinicalTrails.gov, we identified all active interventional clinical trials in diabetic eye disease since 2017. After geolocating every trial site, we used an origin-destination cost-matrix to calculate the driving distance and travel time from the population-weighted United States census tract centroid to the nearest site. We then used public databases to identify census tract-level socioeconomic factors predictive of driving distance and time.Main Outcome Measures: Driving distance > 60 miles and time traveled > 60 minutes to the nearest clinical trial site.Results: In a multivariate model, driving distance of more than 60 miles had a significant association with rural versus urban location (adjusted odds ratio, 5.22; 95% confidence interval [CI], 3.75-7.26; P < 0.001), percentage of population at less than 200% of federal poverty level compared with the fourth quartile (first quartile: adjusted odds ratio, 0.40 [95% CI, 0.29-0.55]; second quartile: adjusted odds ratio, 0.60 [95% CI, 0.47-0.77]; third quartile: adjusted odds ratio, 0.76 [95% CI, 0.63-0.91]; P < 0.001) and the Midwest (adjusted odds ratio, 2.15; 95% CI, 1.13-4.07; P = 0.02), South (adjusted odds ratio, 2.71; 95% CI, 1.23-5.99; P = 0.01), and West (adjusted odds ratio, 3.01; 95% CI, 1.21-7.54; P = 0.02) regions as compared with the Northeast. Driving distance was associated with county-level prevalence of diabetes in the univariate model (odds ratio, 1.12; 95% CI, 1.06-1.19; P < 0.001), although it was nonsignificant in the multivariate model. Similar predictors were found for time traveled in minutes.Conclusions: Geographic maldistributions of clinical trial sites exist for diabetic eye disease in the United States. Those with higher travel burden are more likely to reside in a census tract that is rural, low income, and from areas outside the Northeast. (C) 2020 by the American Academy of Ophthalmology