A decrease rather than an increase in kidney graft size during the first year after deceased-donor kidney transplantation strongly predicts subsequent graft dysfunction, new findings suggest.

Compared with transplant recipients who experienced an increase in graft size, those who had a decrease had a significant 4.5 times higher risk of a composite outcome of a 50% or greater reduction in estimated glomerular filtration rate (eGFR) or end-stage graft failure during the first year post-transplant in adjusted analyses,  researchers reported in Transplantation (2016;100:1759-1766). They had a significant 4.4 higher of a 50% or greater reduction in eGFR and 5.4 times higher risk of end-stage graft failure.

In an observational study of 319 deceased-donor kidney transplant recipients, a team at University Medical Centre in Ljubljana, Slovenia, led by Miha Arnol, MD, PhD, found that 121 patients (38%) experienced a decrease in graft size and 198 (62%) had an increase at 1 year post-transplant. After a median follow-up of 53 months, 41 patients with a decrease in graft size reached the composite outcome compared with 12 who had an increase (34% vs 6%, respectively).

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The investigators measured graft size by ultrasound-Doppler examination. They defined graft size as the longest bipolar of the kidney, measured as the maximum diameter in a sagittal plane parallel to the long axis of the kidney.

Dr Arnol’s team noted that the mechanisms by which graft size affects transplant outcomes have long been a matter of investigation. Some researchers have suggested that intraglomerular hypertension and hyperfiltration leading to nephron loss has a role. “Data from our study suggest that variation in kidney [graft size] during the first year after transplantation may influence the development of immune-mediated injury.”

Recipients who had a decrease in graft size were more likely to experience rejection, and they had a greater incidence of rejection-associated graft failure, according to the investigators.

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