Geographic disparities in access to clinical trial sites exist for neovascular age-related macular degeneration (nAMD) in the United States, according to a study presented at the 38th Annual Scientific Meeting of the American Society of Retina Specialists. While proximity to urban centers is beneficial for efficiency and retention of subjects, the researchers identified populations with a high travel burden to sites, which may contribute to under-representation.
“In recent decades, the expanding pipeline of clinical trials has offered new therapies to improve visual outcomes in nAMD,” the study team wrote. “Including subjects from diverse backgrounds has important implications for data generalizability and improved access to innovative care. Understanding accessibility to clinical trials is imperative to address the disease burden of nAMD for all populations in the US.”
The researchers conducted a cross-sectional, retrospective study, analyzing census tract-level data from public datasets and trial-level data from ClinicalTrials.gov. The primary outcomes were driving distance (greater than 60 miles) and time (greater than 60 minutes) from the population-weighted US Census tract centroid to the nearest clinical trial site, using geographic information systems software. They included 42 trials involving nAMD across 829 unique clinical trial sites in the US.
Travel Burden Significantly Linked With Access to Sites
The study team found upon multivariable regression that driving distance greater than 60 miles was significantly associated with rural location (adjusted OR [aOR] 5.54; 95% CI, 3.86-7.96) and Midwest (aOR 2.30; 95% CI, 1.21-4.38) and South (aOR 2.43; 95% CI 1.21-4.91) versus Northeast residence, as well as some college (aOR 1.02; 95% CI, 1.01-1.04) or an associate degree (aOR 1.05; 95% CI, 1.00-1.10) when compared with a bachelor’s degree. Lower odds of driving greater than 60 miles were associated with census tracts with a higher percentage of Blacks (aOR 0.98; 95% CI, 0.97-0.99), Hispanics (aOR 0.97; 95% CI, 0.95-0.99) and Asians (aOR 0.90; 95% CI, 0.88-0.93) compared with Whites, as well as a lower percentage of the population less than 200% of the federal poverty level. Time traveled greater than 60 minutes had similar predictors in regression modelling.
The study team concurs that more research is needed to characterize the current state of generalizability of clinical trials in nAMD.
