What is KDPI and does it matter?
The kidney donor profile index (KDPI) is used in the new kidney allocation system to match the longevity of the kidney with that of the recipient to maximize the years of life gained through transplantation. It combines 10 donor factors into a single number that summarizes the potential risk of graft failure after kidney transplant.
It is not intended to serve as the only metric for determining donor suitability. Indeed the C-statistic for this is 0.6, which is a little better than a coin toss. Many of the factors have no bearing on long-term function. Pediatric en-bloc kidneys and dual kidneys from older donors will have very high KDPI even though they will work far better than a single adult kidney with KDPI<85. It is an improvement over the old system of standard criteria and extended criteria kidneys, but far from perfect.
Given the poor relationship to outcomes, I do not place much value on this in my practice. In my experience the factors that are more predictive of a durable outcome are:
- the donors instability and comorbidies ( diabetes, hypertension, icu support requirements)
- the kidney biopsy ( glomerculosclerosis, interstitial fibrosis, arteriosclerosis)
- cold ischemia time (time from clamping the vessels in the donor to restoring blood flow in the recipient)
- the kidneys performance on the pulsatile perfusion machine
- recipients vascular disease (most kidneys are lost because the recipient dies with a functioning kidney)
- recipients ability to tolerate a rejection or infection episode.
- recipients compliance with medical care ( taking care of diabetes, blood pressure, immunosuppressants)
- regular followup with their transplant center.
- good insurance and solid support system
The newer non-nephrotoxic immunosuppressant, Nulojix, has shown better graft function and increased patient survival at 7 year. This is used in more than half of the patients receiving a transplant at the Iowa Methodist Transplant Center. The other patients are maintained on tacrolimus based immunosuppression.
So, KDPI is an improvement on the older system but it does not determine longterm kidney function. I do no place a too much emphasis on KDPI when evaluating kidney offers for transplant. The donor and recipient factors I have outlined above are far more important.
|pediatric en-bloc kidneys and dual kidney have very high KDPI despite having better long-term function compared to a single kidney transplant.|