Longer cold ischemic time (CIT) is associated with an increased likelihood of delayed graft function (DGF) and graft loss among recipients of kidneys from living donors older than 50 years, according to a new study.
Using data from the Australia and New Zealand Dialysis and Transplant registry, a team led by Wai Lim, MBBS, PhD, of the Sir Charles Gairdner Hospital in Perth, Western Australia, studied 3,717 patients who received live-donor kidney transplants from 1997–2012. The median follow-up was 6.6 years.
Of the 3,717 patients, 224 (25%) had a CIT of more than 4 hours but not more than 8 hours. Among recipients who received kidneys from donors older than 50 years, each hour increase in CIT was associated with a significant 28% increased odds of DGF in adjusted analyses, Dr. Lim’s team reported online in the American Journal of Transplantation. In addition, compared with a CIT of 1–2 hours, a CIT of more than 4 hours but not more than 8 hours was associated with a nearly 2-fold increased risk of both overall and death-censored graft loss, according to the investigators. The researchers observed no association between CIT and graft loss among recipients of kidneys from younger donors.
“Attempts to reduce CIT in live-donor kidney transplants involving older donor kidneys may lead to improvement in graft outcomes,” the authors concluded.
Dr. Lim and colleagues observed an inverse association between CIT and acute rejection among recipients of kidneys from donors older than 50 years, with each hour of CIT associated with a significant 8% decreased risk of any acute rejection and 27% decreased risk of multiple rejections in adjusted analyses.
“Given the acceptance of paired kidney exchange program worldwide where regional transport of live-donor kidneys may lead to extended CIT, it is critical to understand the association between CIT and live-donor graft and patient outcomes,” the authors noted.
In background information provided in their paper, the researchers noted that the association between prolonged CIT and adverse graft and patient outcomes is well established among recipients of deceased-donor kidneys, but less well established among recipients of live-donor kidneys.
In a previous study of 38,467 recipients of live-donor kidneys published in the American Journal of Transplantation (2007;7:99–107), Dorry L. Segev, MD, PhD, of Johns Hopkins University in Baltimore, and colleagues found that prolonged CIT was not associated with worse renal function and acute rejection (AR) at 1 year following transplantation or with worse allograft survival.
For the study, the investigators placed recipients into 4 groups based on CIT duration: 0–2, 2–4, 4–6, and 6–8 hours. The adjusted rates of DGF were 4.7%, 4.9%, 8.3%, and 9.2%, respectively. Compared with recipients with a CIT of 0–2 hours, only those with a CIT of 4–6 hours had a significantly increased likelihood of DGF. “Notably, this small increase in DGF that occurred with increased CIT was not associated with compromised renal function at 1 year or an increased rate of AR during the first year of transplantation.”