Although longer cold ischemia time is associated with poor kidney transplant outcomes, its influence on graft survival is “modest” compared with the kidney donor profile index (KDPI), a new study concludes.

“Transplant programs should not consider prolonged CIT as a predominant reason to decline an organ, a recommendation that is particularly relevant when kidneys are transported beyond the 250-nautical mile radius,” according to Suphamai Bunnapradist, MD, MS, of the David Geffen School of Medicine at UCLA in Los Angeles, California, and colleagues.

Using 2000-2018 data from the Organ Procurement and Transplantation Network/United Network of Organ Sharing database, the investigators identified 179,347 deceased donor kidney transplant recipients. Cold ischemia time was 16 hours or less, 16-24 hours, 24-32 hours, 32-40 hours, and more than 40 hours for 46.8%, 33.3%, 14.0%, 4.1%, and 1.8% of transplants, respectively.

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The proportions of recipients in these cold ischemia time categories experiencing delayed graft function were 20.9%, 28.1%, 32.4%, 37.5%, and 35.8%, respectively, the investigators reported in Kidney Medicine. Primary nonfunction also significantly increased from 1.1% to 1.5%, 1.8%, 2.5%, and 2.2%, respectively. Median serum creatinine at 1 year after transplantation was 1.3 mg/dL for a cold ischemia time up to 24 hours and 1.4 mg/dL for longer cold ischemia times, but did not differ clinically.

Across each category of cold ischemia time, the investigators found significantly higher graft survival when kidney donor profile index (KDPI) was less than 85% vs more than 85%. In recipients of a kidney with a KDPI less than 85%, the 10-year death-censored graft survival rates were 71.0%, 70.5%, 69.6%, 65.5%, and 67.2% for patients with a cold ischemia time of 16 hours or less, 16-24 hours, 24-32 hours, 32-40 hours, and more than 40 hours, respectively, compared with 53.5%, 50.7%, 50.3%, 50.7%, and 48.3%, respectively, in recipients of a kidney with a KDPI more than 85%.

“This suggests that lower KDPI organs can better endure ischemic injury and recover from [delayed graft function] without long-term detrimental effects to long-term graft function,” Dr Bunnapradist’s team wrote.

In a multivariate regression analysis adjusted for KDPI and other factors, a cold ischemia time of 16-24, 24-32, 32-40, and more than 40 hours independently predicted a 7%, 15%, 25%, and 41% increased risk for graft failure, respectively, compared with a cold ischemia time of 16 hours or less.

The investigators acknowledged that use of machine perfusion may have played a role in acceptance of organs with longer cold ischemia time as well as in prevention of injury to the transplanted organ.


Lum EL, Homkrailas P, Abdalla B, Danovitch GM, Bunnapradist S. Cold ischemia time, kidney donor profile index, and kidney transplant outcomes: A cohort study. Kidney Medicine. Published online November 13, 2022. doi:10.1016/j.xkme.2022.100570