Background: Transplantation provides numerous benefits, but racial/ethnic and gender disparities in access to renal transplantation exist globally. However, in the United States, the interaction between race/ethnicity and gender in transplant access has not been well explored.  Further, it is unclear how age at diagnosis modifies these disparities. 

Methods: We used the United States Renal Data System to identify a retrospective cohort of incident adult dialysis patients from January 1, 2005 – December 31, 2017 and followed through 2018. We used multivariable Cox regression to model the association between combined race/ethnicity and sex (race x gender) group and time to renal transplant waitlisting. We adjusted for clinical and sociodemographic factors and included a time-dependent covariate reflecting a 2014 change in the national kidney allocation policy (KAS) aimed to improve equity. We incorporated a race x gender x age group interaction term to test for effect modification by age group. We also conducted stratified analyses per age group.

Results: After excluding prior renal transplant recipients (n=5,227) and pre-emptive transplants (n=3,486), we identified 1,337,386 US incident dialysis patients of whom 19.4% were waitlisted (median time to waitlisting (interquartile range): 350 days (184, 651)). Most patients were over 50; 50-59 (n=215,028, 19.8%), 60-69 (24.8%), or 70 or greater (37.2%). Waitlisting was highest among Asian women aged 18-39 (n=6,260, 69.7%) and lowest among Hispanic women aged 70 or greater (n=2,315, 1.9%). We found significant effect modification by age in the association of demographic group and time to waitlisting (p-value: <0.0001).
Across all age groups, Black women experienced reduced access to transplant waitlisting compared to age-matched white men; this disparity was worst among the oldest (aged 70 or greater) (adjusted hazard ratio (aHR): 0.60, 95% confidence interval (CI): 0.56, 0.64) and youngest (aged 18-39) Black women (aHR: 0.77, 95% CI: 0.74, 0.79). Furthermore, older Hispanic and white women (60-69 and 70 or greater) exhibited reduced transplant access compared to aged-matched white men and men within their own race/ethnic group. Hispanic women aged 70 or greater experienced worst disparity with 42% reduced likelihood of waitlisting compared to white men (aHR: 0.58, 95% CI: 0.53, 0.64).

Conclusions: The interaction between race/ethnicity and gender in access to renal transplant waitlisting in the United States varies significantly by age. Older Black and Hispanic women and younger Black women have significantly reduced access to transplantation compared to other groups, even after adjusting for clinical and sociodemographic factors. More work is needed to understand and ameliorate these intersections of gender, race/ethnicity, and age-related disparities to promote equity in access to renal transplantation.