P HOWSON1, A IRISH2, L D’ORSOGNA3, G WONG5, W LIM1,4
1Department of Renal Medicine, Sir Charles Gardiner Hospital , Nedlands, Australia, 2Department of Renal Medicine, Fiona Stanley Hospital , Murdoch , Australia, 3Department of Clinical Immunology, Fiona Stanley Hospital , Murdoch, Australia, 4School of Medicine, University of Western Australia , Nedlands , Australia , 5Centre for Transplant and Renal Research Westmead Hospital , Sydney , Australia
Aim: To examine the associations between ethnicity, biopsy-proven acute rejection (BPAR) and death censored allograft failure, and to determine whether BPAR mediated the effect between ethnicity and death censored allograft failure.
Background: Kidney transplantation in Indigenous Australians is associated with poorer allograft outcome compared to non-Indigenous Australians. The patterns, incidence and impact of acute rejection in this population is not well described.
Methods: Prospective population cohort inclusive of all kidney-only transplant recipients between 2000 and 2010 at all 3 tertiary hospitals in Perth, Western Australia. Outcomes measures: BPAR and death censored allograft failure.
Results: Of 616 kidney transplant recipients, 57 (9.3%) were Indigenous Australians. Compared with non-Indigenous recipients, Indigenous recipients were more likely to have diabetes, experienced longer waiting time and had received kidneys with a higher number of HLA-mismatches. During a median (IQR) follow up of time of 7.9 (5.7) years, Indigenous recipients were more likely to experience BPAR and death censored allograft failure compared to non-Indigenous recipients, with adjusted HRs of 2.17 (95%CI 1.52, 3.09, p<0.001) and 2.00 (95%CI 1.13, 3.54, p=0.017), respectively. Of those who had experienced BPAR, antibody mediated rejections were more common in Indigenous compared to non-Indigenous recipients. Mediation analysis showed that 45% of the effect between ethnicity and death censored allograft failure were mediated by BPAR.
Conclusions: Indigenous kidney transplant recipients experienced poorer allograft outcomes compared to non-Indigenous recipients. An increased risk of acute rejection episodes was a significant mediator of the increased risk of death censored allograft failure. Initiatives to reduce acute rejection episodes, and further research identifying other risk factors and mediators associated with poor allograft outcome in Indigenous recipients should be considered a priority.