Donor age and cold ischemia interact to produce inferior 90-day liver allograft survival

Background. Expanded regional sharing of liver allografts may increase cold ischemia and allograft failure, particularly with livers from older donors. The aim of this study was to examine whether older donor age and cold ischemic time interact to produce inferior allograft survival. Methods. We undertook a retrospective cohort study of adult liver transplants in the United States performed between December 1, 1995 and December 31, 2005, using data from the Organ Procurement and Transplantation Network. The primary outcome was allograft failure within 90 days. Results. Forty-four thousand seven hundred fifty-six liver transplant recipients were analyzed. Older age was defined as 45 years or more, and prolonged cold ischemia was defined as 12 hours or more. Using data from the pre-Model for End Stage Liver Disease (MELD), post-MELD and combined eras, three separate analyses of the interaction between older donor age and prolonged cold ischemia were performed. In multivariable logistic regression, the interaction of age 45 years or more and cold ischemia more than or equal to 12 hr reached statistical significance in the combined (OR 1.24, CI 1.08-1.42, P<0.01) and pre-MELD (OR 1.26, CI 1.08-1.46, P<0.01) datasets, but not in the smaller post-MELD dataset (OR 1.18, CI 0.81-1.72, P=0.38). In the combined dataset, recipients of livers from donors aged 45 years or more and cold ischemia more than or equal to 12 hr showed an adjusted absolute risk of allograft failure at 90 days of 17.3% (odds ratio 1.84), compared with 11.1% for recipients of livers from donors older than 45 years and cold ischemia less than 12 hr. Conclusions. These findings suggest that older donor age and prolonged cold ischemia interact to increase liver allograft failure at 90 days. Proposals to expand regional sharing of older livers should be regarded with caution.