Characteristics Associated with Liver Graft Failure:

The Concept of a Donor Risk Index

American Journal of Transplantation 2006; 6: 783–790S. Fenga, N.P. Goodrich,

J.L. Bragg-Gresham, D.M. Dykstra,J.D. Punch, M.A. DebRoy, S.M. Greenstein

R.M. Merion

Ri 張立禹

Introduction

Increasing organ utilization / Progressive shortage of donor organs

Increasing awareness of potential impact of aggressive organs utilization

The Model for End-Stage Liver Disease (MELD): solely based upon transplant candidate

Quantitative descriptions of organ quality, solely based upon donor characteristics

Materials & Methods (Data source)

Data source: the Scientific Registry of Transplant Recipients (SRTR)

Duration: 1998/1/1-2002/12/31

20,023 transplants

Deceased donor

Multiple organ transplants: excluded

Materials & Methods (Analytic methods)

Cox regression models

Time to graft failure: Transplantation to Retransplantation/ Recipient death

The median follow-up time: 3 years

Age, sex, race, ethnicity……

Recipient and transplant factors: adjusted to isolate the impact of donor characteristics.

Results -Donor and recipient characteristics-

Results -Risk factors for graft failure-

7 risk factors has significant association with liver graft failure:

1. Age

2. Race

3. Height

4. Cause of death (COD): CVA

5. COD: Other (not trauma/ CVA/ anoxia)

6. Donation after cardiac death (DAD)

7. Split/ Partial graft

“Donor Demographic Characteristics”

Age:

>40 years- increased risk of graft failure

>60 years– the strongest risk factor for graft failure

Race:

African-American– 19% higher than white donor

Height:

Stronger than body weight

“Cause and Type of Donor Death”

COD CVA:

COD Other:

Both have higher risk of graft failure (16% and 20%)

DCD:

51% higher risk of graft failure

Split/ Partial graft:52% higher risk of graft failure

--Two Transplant Factors--

Cold ischemia time:

↑1% risk of graft failure/ addition hour

Sharing outside of the local donor service area:

Outside the local area: ↑11%

Nationally shared: ↑28%

Results -Transplants according to donor risk index-

RR of graft failure vs donor factor alone

Donor risk index = exp[(0.154 if 40≤ age <50) + (0.274 if 50≤ age <60) + (0.424 if 60≤ age <70) + (0.501 if 70 ≤ age) +(0.079 if COD = anoxia) + (0.145 if COD = CVA) + (0.184 if COD = other) + (0.176 if race = African American) + (0.126 if race = other) +(0.411 if DCD)+(0.422 if partial/split)+(0.066 ((170–height)/10))+(0.105 if regional share)+(0.244 if national share)+(0.010×cold time)].

Results -Recipient characteristics associated with utilization

of grafts with higher donor risk index -More likely to receive higher risk donor index organs

Older

Youngest

Woman

Recipient without HCV

Low disease severity (MELD score 10-14)

Results -Liver disposition by donor risk index categories-

↑Risk index ,↑Higher discard rate

Discard rate:Risk index > 1.5 twice than risk index ≤ 1.1

Discussion

7 donor & graft characteristics are significantly and independently associated with graft failure.

Could compare the relative risk and the candidate’s disease severity at the time of organ offer

Age:

A negative factor

Donor age > 40 years are increasing (1988: 13%; 2003: 54%)

Reflect the increasing disparity of organ demand and supply

Split/partial or DCD grafts:

Associated with >50% risk of graft failure

Only 2.0% and 1.1% of all transplantation now, but will likely continue to increase

-Other Risk Factor-

Not achieve significance in this study:Female sex, Obesity,↑Liver function test (AST/ALT), hypotension/ increased pressor use, and ↑[Na+]

Macrosteatosis and Cold ischemia timeBoth strongly associate with outcome in other study

Macrosteatosis:

Not easily detect while organ offering (frozen section)

Not significantly associate with outcome in this study

Cold ischemia time

Estimated while organ offer

Included in this study’s donor risk index

Ideal graft (ex: from donor <40 years, brain death secondary to trauma or anoxia)

A relatively homogenous outcome group

Non-ideal graftA heterogeneous outcome group

The multitude of possible risk factor combinations presented by the donor pool

The risk continues to increase:

Age of donor↑, Frequency of DCD donor↑, Split/ partial grafts↑

Ironic, split graft have been seen as ideal if transplanted as a whole organ

Split graft: increased the patient transplanted & the net gain of life year

-The candidate who have the greatest risk without graft transplantation-

Have the greatest survival benefit form transplantation

May have disproportionately poorer outcomes with higher risk graft

Compare to delayed transplantation, immediate transplantation with graft bearing a 50% risk of primary liver failure provide a higher 1-year survival rate

-Discard Rate-

Higher discard rate for organs with higher donor risk index, but modest (3.1% in risk index of 1.0 to 12.5% in risk of 2.0 or greater)

→ the willingness to accept increased risk from suboptimal donor quality (more imminent consideration of candidate mortality in the absence of transplantation)

The decision to accept either the risk of transplantation or the risk of waiting must be decide rationally.

The risk posed by the graft offering

The risk of death from progressive liver disease

This study provides an important quantitative assessment of relative risk of every potential graft, based upon donor and graft characteristics

Thanks For Your Attention