Ischemic Times and 1-Year Outcomes in Kidney Transplantation

Previous studies have examined the effects of cold and warm ischemia times on graft function following kidney transplantation. Results of those studies have suggested that extended cold ischemia time (CIT) or extended warm ischemia time (WIT) were independently adversely associated with graft survival. However, according to Christopher Seet, MD, and colleagues at the Royal London Hospital, London, United Kingdom, there are few data available on analyses of both cold and warm ischemia times.

Dr. Seet et al. conducted an analysis to determine whether there is a significant association between a composite measure of cold and warm ischemic time and graft function. Results of the study were reported during a virtual poster session at the 28th International Congress of the Transplantation Society in a poster titled Effect of Cold, Warm, and Composite Ischaemic Times on One Year Graft Function.

The analysis included all kidney transplants conducted at the Royal London Hospital between April 2017 and March 2018. Cases where CIT, WIT, or 1-year creatinine measurements were not available were excluded. The final analysis cohort included 107 cases. Cutoffs of 15 hours for CIT and 35 minutes for WIT were used.

The analyses compared mean 1-year creatinine for cohorts with long versus CIT and long versus short WIT. The effect of CIT and WIT on delayed graft function was examined. In addition, cases were stratified into four groups based on length of CIT and WIT: low CIT/low WIT; low CIT/high WIT; high CIT/low WIT; or high CIT/high WIT. Mean 12-month creatinine levels between each group were compared.

In the overall cohort, there were a relatively small number of patients with long CIT >15 hours (n=17) compared with CIT <15 hours (n=86). However, an extended CIT of 15 hours had a significantly increased mean creatinine level at 12 months post-transplant compared with CIT <15 hours (173 vs 148 mmol/L; P=.02). Grafts with WIT >35 minutes also had significantly raised creatinine compared with WIT <35 minutes (64 vs 131 mmol/L; P=.006).

Following stratification into the four groups, there was a significant difference in mean creatinine in grafts with long CIT/long WIT compared with the other groups. There was no difference in mean creatinine among the other groups. The groups were also similar in delayed graft function.

The differences in high CIT/high WIT and high CIT/low WIT were greatest (mean difference 87 mmol/L; P=.012), followed by low CIT/low WIT (76 mmol/L; P=.001), and low CIT/high WIT (mean difference 53 mmol/L; P=.04). At 1 year post-transplantation, the worst graft function was associated with an extended cold and warm ischemia time; however, the results suggest that WIT may have a greater impact on long-term function than CIT.

“The durations of WIT and CIT have previously been shown to adversely affect graft function. A composite measure of CIT and WIT may be useful in predicting longer term outcomes in kidney transplantation. Our study suggests that WIT has a greater impact on graft function than CIT, and that maintaining CIT <15 hours and WIT <35 minutes is associated with improved one year creatinine,” the authors said.

Source: Seet C, Shetty S, Chowdary P, Mohamed IH,  Khurram M. Effect of cold, warm, and composite ischaemic times on one year graft function. Abstract of a poster presented at the virtual 28th International Congress of the Transplantation Society (Abstract P-11.70), September 13-16, 2020.