Weight change trajectories in Aboriginal and Torres Strait islander Australians after kidney transplantation: a cohort analysis using the Australia and New Zealand Dialysis and Transplant registry (ANZDATA).

BACKGROUND: Weight change post-kidney transplantation and its associations in Aboriginal and Torres Strait Islander Australians, a group known to have poor patient and graft outcomes, are unknown. Weight change based on body mass index in Aboriginal and Torres Strait Islander Australian recipients was compared to non- indigenous recipients.

METHODS: We performed a cohort analysis of data from the Australia and New Zealand Dialysis and Transplant Registry for first deceased donor kidney transplant recipients between 1995 and 2014 in Australia. Weight change post-kidney transplantation was analysed by recipient ethnicity using multivariate mixed effect linear regression analysis.

RESULTS: There were 343 (5.24%) Aboriginal and Torres Strait Islander Australian kidney transplants recipients from a total of 6550 recipients. They had higher pre-transplant BMI (p < 0.001), higher rates of current smokers (p < 0.001), diabetes (p < 0.001), coronary artery disease (p < 0.001), cerebrovascular disease (p = 0.011) and peripheral vascular disease (p = 0.013), ≥4 HLA mismatches (p < 0.001), graft loss (p < 0.001), mortality (p < 0.001) and rejection rates (p < 0.001). Weight increased in the first 2 years post-transplantation in both Aboriginal and Torres Strait Islander Australians and non-indigenous Australians. After adjusting for the baseline differences, weight change diverged significantly at 6, 12 and 24 months. The difference was most marked between 6 and 12 months. When stratified by pre-transplantation BMI, all groups except underweight reflected this pattern. Normal weight and obese Aboriginal and Torres Strait Islander Australian recipients had substantial increase at 12 and 24 months and overweight at 6, 12 and 24 months. The difference in BMI trajectories between Aboriginal and Torres Strait Islander Australians and non- indigenous Australian transplant recipients persisted after adjustment in multivariate mixed effect linear regression analysis.

CONCLUSIONS: Post-kidney transplantation weight gain in this high-risk population is substantial and greater than in non-indigenous Australians. Further studies should assess the effect of treatment factors and weight gain on transplant and recipient outcomes.