Comparative Analysis of Rural-Urban Definitions in Predicting Surgeon Workforce Supply

There are multiple different systems that define a rural area in health services research, but few studies compare their ability to measure access to health resources. Our objective was to compare various definitions of rurality to determine which system best measures local surgeon supply.

In this retrospective observational study, we used the 2019 Area Health Resource File to obtain the 2017 county-level supply of general surgeons, surgical subspecialists, and total physicians for all counties in the United States. Physicians per 100,000 population were calculated for each physician measure and were the primary outcomes. The rural-urban measurements included were the Office of Management and Budget 2017 definition, Urban Influence Codes (UIC), Rural-Urban Commuting Codes (RUCCs), and Census urban population within the county. We also developed and tested a measure combining the RUCCs and Census urban population. Linear regression was used to compare performance of these definitions for each outcome using adjusted R² values.

In 3138 counties included in the study, dichotomous measures of rural-urban using the UIC/RUCC had the lowest adjusted R² values across all outcomes. Quartiles using the Census urban population and the RUCC/Census urban population combined measure had the highest adjusted R² values for all outcomes.

The Census urban population had the best performance in measuring geographic access to surgical care. This study can inform surgical health services researchers who want to include measures of rurality in their analysis.