Most isolated intestinal graft losses are immunological. We conducted a pilot study to evaluate the feasibility of national sharing of HLA no-mismatch allografts for cadaveric isolated intestinal transplantation.
Methods: UNOS data were analyzed in a theoretical model. Part I: All solid organ donors between 1/95-8/97 who would have met criteria for bowel donation were considered potential donors for all recipients who actually received isolated intestinal transplants during this period. We then determined how many donor intestines could have been directed to no-mismatch candidates had national sharing been in place. Donor exclusion criteria were CMV+ donors to CMV- recipients, hemodynamic instability, age >50, size mismatch (donor weight greater than recipient), and obesity. Mean and median waits for transplants, as well as theoretical mean and median waits for transplants that would have occurred given national sharing, were calculated. Part II: We estimated, based on registry graft survival data, the number of intestinal transplants necessary to demonstrate a no-mismatch graft survival advantage at 2 years.
Results: Part I: Although no actual cadaveric no-mismatch transplant was performed, 12-17% of patients could have received no-mismatch allografts had sharing been in place, using various donor acceptance criteria. The impact on waiting time was variable. Part II: Accepting a 15% rate of no-mismatch cases and a survival advantage of 10% at 2 years, 793 transplants would be required to prove an advantage to HLA matching at P<0.05. If the graft survival advantage were 20% at 2 years, the time to show significance would be approximately 5 years. Using early acute rejection as an endpoint could require fewer transplants (93), and only a few years to complete the study.
Conclusions: National sharing of cadaveric isolated intestinal allografts is feasible. Median waits would not be significantly increased. The time necessary to prove graft survival advantage would be considerable, but a difference in the rate of acute rejection could be seen within 2 years. Additionally, a national sharing arrangement might improve the overall outcome of isolated intestinal transplantation.