Differences in access to kidney transplantation for Indigenous Australians

Introduction: In Australia, disparities in access to transplantation for indigenous Australians have been reported. Whether these are the result of lower rates of placement on the waiting list or lower likelihood of transplantation once on the waiting list is not known. In this study we examined the likelihood of placement of indigenous Australians in the transplant waiting list and compared with non-indigenous Australians. We also examined other predictors for listing; including interactions between comorbidities and indigenous status. Among those listed, we examined the likelihood of transplantation and other outcomes (including death) among indigenous versus non-indigenous groups.

Methods: This is an analysis of records from the ANZDATA registry. All patients registered with ANZDATA who started renal replacement therapy (RRT) from 28 June 2006 to 31 December 2012 in Australia aged 18 to 60 years at RRT initiation are included. This cohort is divided into two groups- one of indigenous Australians (Aboriginal and Torres-strait island patients, ATSI) and other with patients from all other ethnicity (non-ATSI). Waiting time is calculated from the first time a patient is active on the waiting list until transplantation, censored for living donor transplantation, death or end of follow-up. Cox regression was used to calculate hazard ratios for wait-listing, and for transplantation. Stata version 13.1 is used for statistical analysis.

Results: 6890 patients meet the inclusion criteria, of whom 1178 are ATSI. Female are more among ATSI (54%) while 38% among non-ATSI, p<0.001. Total of 2219 patients are active on the wait list within the study duration. ATSI are less likely to be wait-listed even when adjusted for age at RRT initiation, comorbidities, smoking, primary renal disease, late referral and body mass index with hazard ratio (HR) of 0.26 (95% CI 0.21, 0.32; p<0.001). However, this effect was not proportional over time; in the first two years of RRT initiation adjusted HR is 0.21 (95% CI 0.17, 0.28; p<0.001) for ATSI versus non- ATSI. From third year, adjusted HR for ATSI to be waitlisted is 0.44 (95% CI 0.30, 0.63; p<0.001). Once listed, HR of likelihood of receiving renal transplant for ATSI patients, adjusted for comorbidities, smoking, primary renal disease, body mass index, gender, age at listing & age at RRT initiation, is 0.61 (95% CI 0.45, 0.84, p<0.005) for ATSI. 58 out of 2219 patients on the waiting list died while waiting for a transplant, of whom 7 are ATSI. HR for ATSI who died (n=7) while waiting for transplant is 3.3 (95% CI 1.48, 7.3, p<0.005).

Conclusions: Disparities in wait listing and transplantation of indigenous patients exist, beyond those explained by measured comorbidities. Indigenous patients are less likely and slower to be listed. This requires further investigation to determine the causes and whether it is the result of unmeasured comorbidities, lack of referral, lack of acceptance or other factors.