Introduction: Although the new acuity circle allocation (ACA) policy has had an improvement in liver transplant (LT) rates in the United States, its effect on other solid organ transplants is unknown.  The ACA has likely resulted in institutional and regional changes in the distribution of deceased donor kidneys as well, especially in the setting of simultaneous liver kidney (SLK) transplantation. We sought to review SLK patterns before and after the institution of ACA and determine if SLK rate changes were associated with a change in kidney transplant (KT) rates and patient and graft survival.

Methods: Data from the Scientific Registry of Transplant Recipients (SRTR) was analyzed to evaluate rates of SLK transplantation before and after the implementation of ACA. Era 1 was defined as January 1, 2018 to February 3, 2020; Era 2 was defined as February 4, 2020 to June 1, 2021. Statistical comparisons between eras were performed.  Transplant programs were divided into high (25%ile), medium (26-74%ile), and low volume (75%ile) KT programs according to Era 1.  Similarly, transplant programs were divided into high (25%ile), medium (26-74%ile), and low volume (75%ile) SLK programs according to Era 1. Transplant volume was assessed for Era 2.

Results: We analyzed 28,085 SLK and 75,058 KT performed in adult recipients from January 1, 2018 to June 1, 2021; 16,799 SLK and 45,168 KT were performed in Era 1 and 11,286 SLK and 29,890 KT were performed in Era 2.  For SLK recipients during Era 1, the 1- and 3-year patient survival was 90.3% and 75.9%, respectively; the 1- and 3-year graft survival was 97.4% and 96.8%, respectively. During Era 2, the 1-year patient and graft survival for SLK recipients was 85.8% and 97.5%, respectively. For KT recipients during Era 1, the 1- and 3-year patient survival was 97.1% and 87.6%, respectfully; graft survival was 97.5% and 93.1%, respectively. During Era 2, the 1-year patient and graft survival for KT recipients was 93.2% and 96.9%, respectively. As a result of ACA, 1,008 additional kidneys went to SLK recipients.  Changes in volume were most evident for low-volume SLK centers with an increase of 8 additional transplants, medium-volume SLK centers (increase of 1.2) and high-volume centers (increase of 4.6); while KT programs generally lost KT with low-volume KT centers with a decrease of 1.7 transplants, medium-volume KT centers (decrease of 1.5) and high-volume centers (decrease of 67).

Conclusion: The institution of the ACA led to differing acceptance practices for SLK recipients with a net efflux of kidneys from solitary KT recipients. Interestingly, patient survival decreased while graft survival improved for SLK recipients while both patient and graft survival decreased for KT as a result of ACA.