Geographic Variation in Cold Ischemia Time: Kidney vs. Liver Transplantation in the United States, 2003-2011

Regional variations in kidney and liver transplant outcomes have been reported, but their causes remain largely unknown. This study investigated variations in kidney and liver cold ischemia times (CITs) across Organ Procurement Organizations (OPO) as potential causes of variations in transplant outcomes.

This retrospective study analyzed the Standard Transplant Analysis and Research (STAR) data of deceased donor kidney (n=61,335) and liver (n=39,285) transplants performed between 2003 and 2011. CIT variations between the two types of organs were examined and compared. Factors associated with CIT were explored using multivariable regressions. Spearman's rank tests were used to associate CIT with graft failure at the OPO level.

Significant CIT variations were found across OPOs for both organs (p < 0.05). The variation was particularly large for kidney CIT. Those OPOs with longer average kidney CIT were likely to have a lower graft survival rate (p=0.01). For liver, this association was insignificant (p=0.23). The regression analysis revealed sharp contrasts between the factors associated with kidney and liver CITs. High risk kidney transplant recipients and marginal kidneys were associated with longer average CIT. The reverse was true for liver transplants.

Large variations in kidney CIT compared to liver CIT may indicate that there is a room to reduce kidney CIT. Reducing kidney CIT through managerial improvements could be a cost effective way to improve the current transplant system.