Introduction: Significant variations in kidney and liver transplant outcomes across OPOs have been reported, but their causes remain largely unknown. This study investigated variations in kidney and liver cold ischemia times (CITs) across OPOs as potential causes of variations in transplant outcomes. Existing literature also suggests differences in the procurement and handling of kidneys as compared to other organs. Our study investigated how this handling difference may be reflected to kidney and liver CIT variations across OPOs.

Materials and Methods: UNOS transplant recipient data between 2003 and 2011 was analyzed. Multivariable regressions with OPO fixed effects were used to examine the CIT variations across OPOs. Spearman's rank tests were used to associate CIT with graft failure at the OPO level. A survival analysis was conducted to measure the effect of CIT on graft failure and to estimate the effect of reduced kidney CIT on 1st, 2nd and 3rd year graft survivals.

Results: Significant CIT variations were found across OPOs for both organs (p < 0.05), after adjusting for graft transfer distance, quality and share type of organs. The variation was particularly large for kidney CIT. Those OPOs with longer average kidney CIT had a lower first year graft survival rate (p=0.008). For liver, this association was insignificant (p=0.23). We found 1st, 2nd and 3rd year graft survival would go up by 1%, 0.3% and 0.2% if kidney CIT was reduced from the current average of 17 hours to 7 hours (the average of liver CIT). This indicates, given that about 10,000 deceased donor kidneys are transplanted annually, an additional 100, 30 and 20 of these recipients would survive beyond one year.

Conclusion: Large variations in kidney CIT compared to liver CIT may indicate that there is a room to reduce kidney CIT by altering the way that kidneys have been handled by some OPOs and centers. Reducing kidney CIT could be a cost effective way to reduce graft failure and to improve the system as the reduction would avoid the need for Medicare coverage on dialysis, as well as the costs associated with relisting and re-transplanting a more complicated patient population.

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