What’s Behind the Jump in Kidney Discard Rate?

A broadening donor pool, increased risk aversion, and inefficient organ allocation may all contribute to the long-term increase in the percentage of deceased donor kidneys discarded, concludes a study in Transplantation.

The researchers analyzed Organ Procurement and Transplantation Network data to explore possible reasons for the well-documented, two-decade-long increase in the US deceased donor kidney discard rate (DKR). Beginning at 5.1% in 1988, the KDR rose more or less steadily to a high of 19.1% in 2009. This trend occurred at a time when the number of kidneys nearly doubled, from 7705 to 14,394. The KDR subsequently stabilized at 18% to 19% between 2010 and 2015. Multivariable regression and propensity analysis were performed to evaluate changes in donor characteristics and other potential explanatory factors.

The findings suggested that at least 80% of the increase in KDR was related to changes in the donor pool and in biopsy and pumping practices. Median donor age increased from 26 years in 1987 to 43 years in 2009, while the median Kidney Donor Risk Index increased from 1.1 in 1994 to 1.3 in 2009. There were also significant increases in black and Hispanic donors, diabetic donors, and donation after circulatory death.

Increased biopsy rates also contributed to the increase in KDR, as did an increase in kidneys pumped. During the 2000s, the percentage of kidneys placed on a pulsatile perfusion pump increased from 10% to 30%. Without this change in pumping practice, the increase in KDR would have been even greater.

The results suggest that the increase in deceased donor KDR from the late 1980s to the late 2000s largely reflected increased age and other changes related to the broadening of the donor pool. The unexplained residual increase may be partly related to behavioral factors including increased risk aversion, with transplant programs lowering their acceptance rates for less-than-ideal kidneys.

Inefficiencies in the organ allocation system may also be a contributing factor. In light of this and previous findings, the researchers conclude that “routine pumping . . . may be a potent and cost-effective way to increase the organ supply by reducing discards” [Stewart DE, et al. Diagnosing the decades-long rise in the deceased donor kidney discard rate in the United States. Transplantation 2017; 101:575–587].

April 2017 (Vol 9, Number 4)