Outcomes in HKT after Change in Allocation System

American Transplant Congress 2021

Heart allograft allocation is the primary determinant for heart-kidney transplantation (HKT) in the United States. S. Rao and colleagues conducted an analysis of the Organ Procurement and Transplantation Network (OPTN) database to compare outcomes of HKT performed under the former heart allocation system (prior-HAS, October 1, 2015-October 18, 2018, n=516) and under the current HAS that prioritizes sicker patients (after October 18, 2018, n=149).

The researchers reported results of the analysis during a virtual presentation at the 2021 American Transplant Congress. The presentation was titled Early Outcome of Heart-Kidney Transplantation in the Current Heart Allocation System in the United States.

The analysis included de-identified data from the OPTN registry with follow-up through December 6, 2019. Data included baseline demographics, comorbidities, and the etiology of cardiac and kidney dysfunction. Inotropic and/or mechanical circulatory support were used to assess pretransplant cardiac support. Serum creatinine level at listing, the need for pretransplant dialysis, and duration of dialysis (short ≤6 weeks, medium 7-12 weeks, and long >12 weeks) were used to assess kidney dysfunction pretransplant.

The percentage of HKT among total heart transplants has increased from 5.3% in the prior-HAS era to 6.4% under the current HAS (P=.038). While the prevalence of pretransplant dialysis was similar between the two groups (~50%), a higher percentage in the current-HAS group were in the short dialysis duration group (24.5% vs 7.3%; P=.01).

Results of univariate Cox regression analysis demonstrated lower 180-day survival in the current-HAS group (87.2% vs 92.4%; hazard ratio [HR], 1.75; 95% confidence interval [CI], 1.01-3.04; P=.04) and a trend toward lower kidney allograft survival (83.9% vs 85.9%; HR, 1.60; 95% CI, 0.09-2.59; P=.05). Following adjustment for covariates, the HAS era was not an independent predictor of outcomes. Delayed graft function of kidney allograft remained a strong predictor of poorer outcomes and was higher in the current-HAS group (35% vs 26%, P=.03).

In conclusion, the researchers said, “Our study shows that the rates of HKT have continued to increase under the current HAS. Similar to the higher mortality in heart transplant recipients under the current-HAS era, patient mortality was higher in the HKT recipients too. This study highlights the need for a novel HKT allocation policy with standardized listing and allocation criteria aimed to improve HKT outcomes.”

Source: Rao S, Doyle A, Brennan D, Constantinescu S. Early outcome of heart-kidney transplantation in the current heart allocation system in the United States. Abstract of a presentation at the virtual American Transplant Congress 2021 (abstract #413), June 6, 2021.