Kidney transplantation and the intensity of poverty in the contiguous United States

Abstract

Background: Geographic variation in kidney transplantation rates in the United States has been described previously but remains unexplained by age, race, sex, or socioeconomic status differences. Geographic variations in the concentration of poverty appear to impact end-stage renal disease care and potentially access to transplantation.

Methods: We studied the impact of how spatial topography of poverty across geographical regions in the contiguous United States is associated with kidney transplantation in the 48 contiguous U.S. states.

Results: We found considerable geographic variation in transplantation rates across the country that persisted across quartiles of county-level median household income and percentage minority population. Higher transplant rates were seen with increasing median household income and decreasing minority populations but were not influenced by education level. Transplantation rates in counties with poverty rates above the national average had low transplant rates, but these rates were influenced by the poverty level in the surrounding counties. Similarly, wealthy counties had higher transplant rates but were lowered in counties of relative wealth that were surrounded by less wealthy counties.

Conclusions: Our results underline the geographical heterogeneity of kidney transplantation in the United States and identify regions of the country most likely to benefit from interventions that may reduce disparities in transplantation.

FIGURE 1

A, statewise median annual transplant rates (calculated by dividing the 15-year transplant rate for each state by 15. The 15-year rate of transplantation for each county was determined by dividing the total number of transplants over the 15-year period studied by the ESRD prevalence in the midpoint [8th] year, i.e., in 2000 for each state). B, county-level distribution of annualized transplant rates (calculated by dividing the 15-year transplant rate for each county by 15. The 15-year rate of transplantation for each county was determined by dividing the total number of transplants over the 15-year period studied by the ESRD prevalence in the midpoint [8th] year, i.e., in 2000 for each county).

FIGURE 2

Variation in transplantation rates across organ procurement regions. Map showing boundaries foreach of the 11 regions (please see Figure S1, SDC, http://links.lww.com/TP/A969 for cartographical depiction of this data).

FIGURE 3

Influence of county-level socioeconomic factors on the rate of kidney transplantation.

FIGURE 4

Impact of county poverty level on the median transplant rate.

FIGURE 5

Influence of spatial topography of poverty on kidney transplantation rates. (The number of counties in each category is listed at the base of the corresponding bar. The average category included 1,242 counties.)