In my last post, I discussed a new paper, A Primer on Kidney Transplantation: Anatomy of the Shortage, that Phil Cook and I just posted to SSRN. The paper provides a quantitative description of the kidney shortage and future trends, and yields some insights on possible policy solutions (and non-solutions) to the kidney shortage.
We wanted to provide a more fine-grained picture of the kidney shortage than what is typically presented, by documenting the flows on and off the kidney waiting list for a single year, 2011. For the sake of brevity I won’t repeat that analysis here, but we conclude that unmet need is at least 21,000 kidneys per year, and very likely more than that. Those interested in the specifics should consult Table 1, Figure 2, and the discussion in Parts IV and V of the article.
In considering where to look for more kidneys, we begin with the basic demographics: the typical criteria that are applied to identifying suitable deceased donors have the effect of disqualifying all but a small fraction of the 2.5 million U.S. deaths per year. Table 3 from our paper, reproduced above right, provides some detail on this “winnowing” process for 2010, gathered by sorting the 2.5 million records from the National Vital Statistics multiple cause mortality dataset according to particular fields in the electronic records, beginning with age. We begin with the fact that almost 2/3 of all deaths are over 70 and hence almost always deemed medically unacceptable due to age alone. Of the remainder, most are uncontrolled deaths out of the hospital, or deaths in the hospital from causes like cancer, diabetes, and renal disease that ordinarily are disqualifying.
The result is that, in 2010, only about 9,000 deaths were “eligible” by either the standard criteria or expanded criteria, and in 70% of those cases the kidneys were in fact donated. (In addition, there were 928 others who became donors after cardiac death, which is uncommon because it is a difficult, though expanding, procedure, which we discuss in more detail in the paper).
One lesson from these statistics is that even a deceased organ consent and allocation system with a 100% success rate would have yielded only an additional 2751 donors, or roughly 5500 kidneys. This is not nearly enough to satisfy current need, particularly if any progress is to be made on the backlog.
Those who believe that the kidney shortage can be eliminated through presumed consent, priority systems, funeral vouchers, or other proposals aimed at improving rates of deceased donation are thus mistaken. Additional kidneys from deceased donors would be welcome, of course, but will not be nearly enough to satisfy current need. Barring a major breakthrough in recovering organs from patients that are currently deemed unsuitable, increasing donations from living donors is the only plausible means to close the gap.
In my next post, I’ll conclude with some more specific policy implications of our paper.