Changing organ allocation policy for kidney transplantation in the United States

Table 1 Formulae for calculating Kidney Donor Profile Index and expected post-transplant survival

KDPI

KDPI = exp (-0.0194 × I[age < 18 year] × [age - 18 year] + 0.0128 × [age - 40 year] + 0.0107 × I[age > 50 year] + 0.179 × I[race = African American] + 0.126 × I[hypertensive] + 0.130 × I[diabetic] + 0.220 × [SCr - 1 mg/dL] - 0.209 × I[SCr 1.5 mg/dL] × [SCr - 1.5 mg/dL] + 0.0881 × I[cause of death = CVA] - 0.0464 × [{height - 170 cm}/10] - 0.0199 × I[weight < 80 kg] × [{weight - 80 kg}/5] + 0.133 × I[donation after cardiac death] + 0.240 × I[hepatitis C] - 0.0766, where I is equal to 1 if the condition is true and I is equal to 0 if the condition is false

EPTS

EPTS score = 0.047 × MAX (age - 25. 0) - 0.015 × Diabetes × MAX (Age - 25.0) + 0.398 × Prior Organ Transplant - 0.237 × Diabetes × Prior Organ Transplant + 0.315 × log(Years on Dialysis + 1) - 0.099 × Diabetes × log(Years on Dialysis + 1) + 0.130 × (Years on Dialysis = 0) - 0.348 × Diabetes × (Years on Dialysis = 0) + 1.262 × Diabetes

EPTS: Expected post-transplant survival; KDPI: Kidney donor profile index.

Table 2 Points awarded to wait-listed candidates in the new kidney allocation system

Candidate features	Points awarded
The waiting time (date of listing with GFR < 20 mL/min, or date of initiation of dialysis)	1 per year (1/365 per day)
Pediatric candidates at time of match with 0- ABDR mismatch donor	4 (if child is 0-10 yr) 3 (if child is 11-17 yr)
Pediatric candidate at time of match if KDPI < 35%	1
Prior living donor	4
Level of sensitization (cPRA ≥ 20%)	0-202, see description
Single HLA-DR mismatch with donor	1
Zero HLA-DR mismatch with donor	2

cPRA: Calculated panel reactive antibody; GFR: Glomerular filtration rate; KDPI: Kidney donor profile index; HLA: Human leukocyte antigen.

Table 3 Comparison of old vs new allocation policies

Old kidney allocation system (effective 1988 - 12/3/2014)	New kidney allocation system (effective 12/4/2014 onwards)
Wait list time starts from time of listing	Wait list time starts from time of listing or date of initiation of dialysis, whichever comes first
The quality of organs described based on the terms SCD, ECD and DCD kidneys	The quality of organs assessed by a KDPI score (0%-100%)
No metric was involved in allocating kidneys depending on the expected long- term outcomes of the transplant candidates	Longevity matching is used to allocate kidneys depending on the KDPI and EPTS scores
Only 4 priority points were given for HLA sensitization for a cPRA ≥ 80%	Gradation of priority points given based on HLA sensitization for cPRA ≥ 20% range from 1-202, which can bring the recipient much higher on the list
Long wait time for blood group B candidates	In order to decrease wait times for B blood group candidates, A2/A2B blood type donors acceptable
Pay back system present	Pay back system eliminated
Priority given to pediatric candidates: share 35 (donor age < 35 yr)	Pediatric candidates still get priority for kidneys with KDPI < 35%
National and regional sharing for sensitized patients was not mandated	National, regional and local priority sharing of organs for highly sensitized patients with cPRA of 100%, 99% and 98% respectively
High discard rate existed for marginal ECD/ DCD kidneys	Regional sharing of marginal kidneys (KDPI > 85%) is proposed

cPRA: Calculated panel reactive antibody; DCD: Donation after circulatory death; ECD: Extended criteria donor; EPTS: Estimated post-transplant survival; KDPI: Kidney donor profile index; SCD: Standard criteria donor.