The Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL) was a consortium of 9 U.S. liver transplant centers performing adult-to-adult living donor liver transplant (AALDLT) with the primary goal of examining outcomes of AALDLT versus deceased donor liver transplant (DDLT). AALDLT is a relatively new procedure increasingly used at major transplantation centers. Relatively small numbers of cases are performed at any one center and approaches to the patient and donor are too diverse across centers to provide reliable and generalizable information on donor and recipient outcomes from individual centers. Therefore, the consortium was organized to accrue and follow sufficient numbers of patients being considered for and undergoing AALDLT to provide generalizable results from adequately powered studies.

The Adult to Adult Living Donor Liver Transplantation Cohort Study (A2ALL) consisted of both retrospective and prospective studies of AALDLT. Legacy data from the A2ALL retrospective cohort is housed in the NIDDK Data Repository. The A2ALL retrospective cohort comprised 819 adult patients, each with a potential living donor, evaluated between January 1, 1998 and February 28, 2003. The retrospective study was designed to gain initial insights into outcomes associated with liver transplant procedures, with data drawn from existing medical records and patient materials. It was hypothesized that pursuit of a living liver allograft leads to decreased pre-transplant morbidity and mortality and better long term outcomes for patients starting from the point at which listed patients have a potential donor evaluated (at least a history and physical examination). The study analyzed numerous variables to determine the factors influencing allograft survival in recipients.

The A2ALL study showed evidence that AALDLT is a viable option for liver replacement with outcomes that improve with center experience. Donor characteristics associated with survival included younger age and cold ischemia time of the right lobe graft.

MRI and CT Scan images from subjects enrolled in A2ALL are not included in the data package, but are available upon request.

The primary study objective of the A2ALL Retrospective Cohort Study is to determine whether the decision to undergo adult-to-adult living donor liver transplant is beneficial for the patients who choose this type of transplant. The principal hypothesis was that receipt of a living liver allograft leads to better long term outcomes for liver transplant candidates than pursuit of cadaveric transplant. Secondary objectives included addressing selected biological and clinical issues in transplantation structured around the comparison between DDLT and AALDLT.

A comparison of the mortality of AALDLT patients to the mortality of patients who have not yet received AALDLT was used as the primary outcome measure. The survival and rejection episodes for AALDLT vs. cadaveric recipients from time of transplant were also compared.

The eligibility criteria for recipients included:

• Potential recipient listed for single organ (liver) transplantation
• Eligible for AALDLT
• At least 18 years of age at the time of donor history and physical exam
• Indication for transplant of non-fulminant liver disease
• Potential donor identified and scheduled for evaluation (history and physical examination) within four weeks

The eligibility criteria for donors included:

• Met donor criteria of the transplant center
• At least 18 years of age at the time of donation
• Evaluated with a history and physical examination at the transplantation center

The A2ALL study showed evidence that AALDLT is a viable option for liver replacement. The donor characteristics associated with acceptance were younger age and cold ischemia time of the right lobe graft. Additionally, data demonstrated that AALDLT is a procedure in which center experience plays a significant role in outcome, with outcomes that improve with experience.