*Purpose: The impact of size mismatch on graft survival in living donor liver transplant is well established but is not a common concern in deceased donor liver transplant (DDLT). Although the effect has been proposed in a few studies, there is still uncertainty about which recipients can safely receive small pediatric and adult grafts. The aim of this study is to investigate recent trends in transplantation of size mismatched livers given shifts in allocation systems and determine the effect of mismatch on graft survival and patient mortality.

*Methods: Using SRTR data, we identified adults (age >18) who received a DDLT between January 2010-March 2021. We calculated donor-to-recipient body surface area ratio (DR_BSAr) as (DR_BSAr=BSA_donor/BSA_recipient). BSA is calculated as √(weight [kg]x height [cm])/3600. Allocation eras were defined as 1/1/2010-6/18/2013 (pre-Share35), 1/19/2013-2/4/2020 (Share 35), and 2/4/2020-3/21/2021 (acuity circles). Patient and graft survival were compared across strata of DR_BSAr (<0.8, 0.8-1.0, >1.0) using Cox regression adjusting for recipient and donor characteristics.

*Results: During the study period 63,785 DDLTs were performed. DR_BSAr was <0.8 for 12% of recipients, 0.8-1.0 for 44% of recipients, and >1.0 for 44% of recipients. The median age of donors in the DR_BSAr <0.8 group was 39 (IQR: 24,54), 42 (28,55) in the 0.8-1.0 group, and 43 (30,55) in the >1.0 group. The number of pediatric donors (age <18) was 883 (11.9%) in DR-BSAr <0.8 group, 1,324 (4.6%) in the 0.8-1.0 group, and 867 (3.0%) in the <1.0 group. For the 3 allocation eras spanning the study period there was no change in the proportion of transplants with a DR_BSAr <0.8 (Fisher exact p=0.69). Compared to DR_BSAr 0.8-1.0, DR_BSAr <0.8 was associated with increased risk of graft loss (aHR=1.09 (1.03-1.16), p=<0.01) but had no effect on mortality (aHR=1.06 (0.99-1.14, p=0.075 (Figure). When removing pediatric donors from the analysis a similar effect was found on graft loss (aHR=1.09 (1.03-1.16), p=<0.01).

*Conclusions: There has been no change in number of DDLT performed in recipients with a DR_BSAr <0.8 since the shift in allocation systems. DR_BSAr of <0.8 is an independent predictor of worse graft survival. Centers should be cautious about size match (DR_BSAR <0.8) not just from pediatric donors but adult donors as well.

« Back to 2022 American Transplant Congress