Not all kidneys are the same Phil Clayton DNT Workshop Launceston 2 March 2015
Outline How the current allocation system works Quality matching in the current system KDRI and EPTS Trends in donor demographics Discard rates Good kidneys to good recipients? Marginal kidneys to marginal recipients? What are other countries doing?
Current Australian model Major listing criteria: ESKD on dialysis 80% likelihood of surviving for at least 5 years after transplantation Major allocation criteria: Blood group Equity Waiting time Equity HLA match Utility Highly sensitised Equity Childhood Utility
0.00 0.25 0.50 0.75 1.00 Death-censored graft survival Australian DD grafts 1995-2009 0 5 10 15 Years HLA mismatch 0 1 2 3 4 5 6
0.00 0.25 0.50 0.75 1.00 Patient survival Australian DD grafts 1995-2009 0 5 10 15 Years HLA mismatch 0 1 2 3 4 5 6
0.00 0.25 0.50 0.75 1.00 Death-censored graft survival Australian DD grafts 1995-2009 0 5 10 15 Years Donor age 0-24 25-34 35-44 45-54 55-64 65+
0.00 0.25 0.50 0.75 1.00 Patient survival Australian DD grafts 1995-2009 0 5 10 15 Years Age 0-24 25-34 35-44 45-54 55-64 65+
100 200 300 400 Age difference (donor minus recipient age) Australian DD grafts 1995-2009 Young donors Old patients Old donors Young patients 0-100 -50 0 50
KDRI Kidney donor risk index Developed by SRTR Components Donor age Hypertension Diabetes Terminal creatinine Cause of death Height Weight DCD status Hepatitis C status Reported in US at time of offer, and used for allocation
KDRI vs donor age Australian deceased kidney donors 2008-2013.5 1 1.5 2 2.5 3 0 20 40 60 80 Donor age (years)
0.00 0.25 0.50 0.75 1.00 Death-censored graft survival by KDRI quintile KDRI quintile 1 2 3 4 5 c=0.69 0 3 6 9 12 Years post transplant Clayton PA et al. TSANZ ASM 2015 (submitted).
EPTS Estimated post-transplant survival score Components Age Diabetic status Prior solid organ transplant Years on dialysis
EPTS vs age Australian kidney-only waiting list 31 December 2013 0 1 2 3 4 0 20 40 60 80 Age (years)
0.00 0.25 0.50 0.75 1.00 EPTS quintile 1 2 3 4 5 Patient survival by EPTS quintile c=0.69 0 3 6 9 12 Years post transplant Clayton PA et al. AJT. 2014 Aug;14(8):1922 6.
100 Kidney risk vs recipient risk Australian DD kidney-only grafts 2008-2012 80 60 40 20 0 0 20 40 60 80 100 EPTS percentile
100 Kidney risk vs recipient risk Australian DD kidney-only grafts 2008-2012 80 60 40 20 0 0 20 40 60 80 100 EPTS percentile
100 Kidney risk vs recipient risk Australian DD kidney-only grafts 2008-2012 80 60 40 20 0 0 20 40 60 80 100 EPTS percentile
Donor demographics Broad push to increase organ donor rates Increasing number of older donors with more co-morbidities ( marginal kidneys)
Deceased Kidney Donor Type Australia 2004-2013 100 200 300 400 0 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 DCD, donor after cardiac death DBD ECD, expanded critera donor after brain death DCD SCD, standard criteria donor after brain death DCD DBD ECD DBD SCD
Donor age over time Australian deceased kidney donors 2000-2013 0 20 40 60 80 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
KDRI over time Australian deceased kidney donors 2000-2013.5 1 1.5 2 2.5 3 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
Referred and actual solid organ NSW donors 2010-2014 Referred Donated 0 20 40 60 2010 2011 2013 2015 Courtesy of Daniel Hirsch. Data from NSW OTDS
Double adult kidney transplants Australia 2000-2013 0 5 10 15 20 1995 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013
10 Discard rate of retrieved kidneys Australia 2005-2014 0 2 4 6 8 2004 2006 2008 2010 2012 2014
Where we are so far Current allocation system doesn t aim to match quality of kidneys with recipients KDRI and EPTS are statistically valid scores to quantify risk Could be used for allocation purposes Increasing number of marginal kidneys Recent increase in discard rate Should we aim to match quality of kidneys and recipients?
Good kidneys to good recipients? Pros Increased utility get the most out of scarce resource Better kidneys go to patients most likely to need regrafting in the future Cons Inequitable patients jumping the queue ; ageism May reduce incentive to find a living donor How to define better kidneys and recipients?
Hippen BE at al. N Engl J Med. 2011 Apr 7;364(14):1285 7.
100 200 300 400 Living donor transplantation rate Australia 2002-2010 Observed Current allocation system Utility-based allocation system Simulated 0 2002 2004 2006 2008 2010 Year
100 Pure utility "Perfect" system 20 40 60 80 Current system Pure waiting time 0 0 20 40 60 80 100 Equity (median % patients waiting less than recipient)
Marginal kidneys to marginal recipients? Pros Reduces likelihood of discards Reduces waiting time for older patients Avoids allocating bad kidneys to people who shouldn t take them Cons Healthy patients offered a marginal kidney can (and often do) decline the offer anyway Reduces organ pool available to healthier (younger) recipients effects on utility may be negative Potentially inefficient allocation since fewer potential recipients for marginal kidneys (? more shipping) How to define marginal kidneys and recipients?
100 "Perfect" system 20 40 60 80 Current Old for old ECD 0 0 20 40 60 80 100 Equity (median % patients waiting less than recipient)
Other models US Longstanding ECD system Designed to reduce discards Discard rate much higher than Aust/NZ New system Allocates top 20% of kidneys to top 20% of recipients Designed to increase utility Europe Eurotransplant Seniors Program 65+ kidneys to 65+ recipients, ABO compatible, HLA mismatches ignored, local allocation UK Allocation score includes a term for age difference
Conclusions Current allocation system does not match kidney and recipient quality This could be done using KDRI/EPTS Need clear understanding of: Goals of system Ethical aspects Potential unintended consequences