Introduction. While racial NIH funding disparities have been identified, little is known about the link between community demographics of institutions and NIH funding. We sought to evaluate the association between institution zip code characteristics and NIH funding. Methods. We linked the 2011-2021 NIH RePORTER database to Census data. We calculated the funding to each institution and stratified institutions into funding quartiles. We defined out independent variables as institution ZIP code level race/ethnicity (White, Black, and Hispanic), and socioeconomic status (household income, high school graduation rate, and unemployment rate). We used ordinal regression models to evaluate the association between institution ZIP code characteristics and grant funding quartile. Results. We included 731,548 grants (US$271,495,839,744) from 3,971 ZIP codes. The funding amounts in millions of U.S. dollars for the funding quartiles were fourth - 0.25, third - 1.1, second - 3.8, first - 43.5. Using ordinal regression, we found an association between increasing unemployment rate (OR = 1.03 [1.02, 1.05]), increasing high school graduation rate (OR = 3.6 [1.6, 8.4]), decreasing proportion of White people (OR = 0.4 [0.3, 0.5]), increasing proportion of Black people (OR = 1.3 [0.9, 1.8]), and increasing proportion of Hispanic/Latine people (OR = 2.5 [1.7, 3.5]) and higher grant funding quartiles. We found no association between household income and grant funding quartile. Conclusion. We found ZIP code demographics to be inadequate for evaluating NIH funding disparities, and the association between institution ZIP code demographics and investigator demographics is unclear. To evaluate and improve grant funding disparities, better grant recipient data accessibility and transparency are needed.
Keywords: NIH; disparities; grant; race; research funding; socioeconomic status.