Profiling immunologic risk for acute rejection in liver transplantation: Recipient age is an important risk factor.

Background: Careful management of induction and maintenance of immunosuppression is paramount to prevent acute rejection in liver transplantation. A methodical analysis of risk factors for acute cellular rejection may provide a more comprehensive method to profile the immunologic risk of candidates.
Methods: Using registry data from the Organ Procurement and Transplantation Network (OPTN), we identified 42,508 adult recipients who underwent orthotopic liver transplant (OLT) between 2002 and 2013. We excluded recipients with a blank entry for treated rejection. We analyzed this all inclusive cohort in addition to a subset of 27,493 patients with just tacrolimus immunosuppression. Multivariate logistic regression was used on both cohorts and identified independent risk factors for treated acute rejection at one year.
Results: Recipient age (reference group was 40 to 60years) was a dominant risk factor for rejection in both cohorts and had a dose response relationship. The strongest risk factors in the inclusive cohort were: age 18-25 (OR 2.20), age 26-29 (OR 2.03), and primary biliary cholangitis (OR 1.55). The most protective factors were age 70 and older (OR 0.68), and age 65-69 (OR 0.70). The rates of rejection had a similar pattern.
Conclusions: Although prior studies have suggested age as a risk factor for rejection in liver transplantation, this is the first study of national-level data to demonstrate a robust dose dependent relationship between age and risk for rejection at one year. Clinicians should place significant weight on recipient age when they assess their recipients for the immunologic risk of rejection.
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