Donor-Recipient Weight Mismatch as a Risk Factor for Delayed Graft Function in Renal Transplantation
Background: Matching of kidney donors and recipients is an important predictor of outcomes following kidney transplantation. Studies have demonstrated weight pairing of donors and recipients (DR) to be particularly important for kidney graft outcomes. Recipients receiving organs from smaller donors have been shown to experience significantly worse outcomes than those receiving kidneys from weight-matched donors. With the rising rates of obesity amongst kidney transplants recipients, the impact of obesity in the setting of DR weight mismatch warrants investigation. We investigated the outcome of delayed graft function, defined as need for dialysis within the first 7 days following transplantation.
Methods: We used a large database to identify kidney transplant recipients. We grouped DR according to their weight mismatch at time of transplantation, which yielded the following 4 groups: weight mismatched DR by >30 kg and 10-30 kg (D>R; D<R). We separately grouped DR according to their obesity status, using a BMI cut point of 30 kg/m2 to identify obese vs. non-obese DR. We determined the likelihood of DGF for each of the DR weight mismatch groups compared to weight matched DR.
Results: A total of 255,480 transplant recipients were included; 18% developed DGF. DGF was highest in the 30 kg weight-mismatched groups (22.4% for D>R; 21.1% for D<R). In all DR obesity pairings, D<R by 30 kg was associated with the greatest risk of DGF versus no weight difference.
Conclusion: Our study demonstrated that the risk of DGF is highest in the setting where recipients are larger than their donors by 30 or more kg. This finding was observed irrespective of DR obesity status. This may be explained by more complicated surgery in the setting of larger recipient-to-donor size. This finding is supported by previous studies which have demonstrated DGF to be linked to more difficult and prolonged transplant surgery.