1. Lung Allocation Score
Marcelo Cypel, MD MSc
Assistant Professor of Surgery
Staff Surgeon
Division of Thoracic
University of Toronto
University Health Network
Marcelo.cypel@uhn.ca
2. Outline
• Principles and Rationale of UNOS LAS
• How it is calculated and who benefits the most
• Overview of lung allocation systems
3. LAS rationale
“ Waiting in line for medical services is common practice but
when life is at stake, triage is a generally accepted way to
apportion medical care”
“Surgery for a ruptured aneurysm “bumps” an electively
scheduled operation. Indeed, a heart transplant bumps an
elective coronary bypass. But who should get the heart?
1) The patient who has waited the longest time?
2) Or the one who cannot wait any longer?
3) What if the patient is so sick that recovery from surgery is
unlikely or compromised?
4) What if one patient is more likely to survive than another?”
Egan, chest 2005
4. Pre-LAS system (seniority list system)
• Excessive wait list mortality
• Pulmonary fibrosis and cystic fibrosis (CF),
compared with COPD
• Transplant benefit questionable as patients
able to wait longer were the ones receiving
organs
5. LAS principles
•To allocate lungs solely on the basis of risk of
death without a transplant would lead to large
numbers of lung transplants being performed in
critically ill individuals who would proceed to die
despite receiving a transplant”
•The LAS is calculated for each patient as a
function of waitlist survival probability without a
transplant and the transplant benefit”.
7. Variable for Calculation of LAS
• FEV1
• Systolic PA
• Supplemental O2
• Age
• Body Mass Index
• Insulin-Dependent DM
• NYHA
• 6 min-walk distance
• Ventilator use
• Creatinine
• PCWP
• PcO2
• Diagnosis
8. Higher LAS for IPF and CF
COPD PAH CF IPF
Yussen, AJT 2010; 10, 1047-1068
14. Wait list and post-Tx mortality
Yussen, AJT 2010; 10, 1047-1068
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15. Conclusion I
• The number of active waiting list patients; the
waiting times for LTx; and the death rate on wait
list have decreased.
• One year survival did not change pre and post-
LAS era.
• Long term outcomes have still to be determined
• Refinement of predictive model is ongoing :
addition of bilirubin, and ECMO as variables
16. In search of the ideal allocation system
• Equity – fair, impartial
• Justice – based on societal values
• Beneficence – patients experience more benefit
than harm
• Utility – maximize the value to society/transplant
recipients as a group
• Transparent
Egan, Am J Transplant 2003; 3: 366--372
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17. Themes underpinning attributes for community
preferences for organ allocation
Community Preferences for the Allocation of Solid Organs for Transplantation:
A Systematic Review.
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Tong, Allison et el; Transplantation 2010; 89(7):796-805
18. Before allocation – the listing decision!
• Similar process around the world
• ISHLT guidelines are just that – actual
practice varies
• Expected post-transplant outcomes may
heavily influence listing decisions
• Program tolerance for risk – affected by
many variables, not explicit
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20. Factors that may implicitly affect listing
decisions
• Size of program – ability to dilute bad outcomes
• Program relationships with hospital, payers, regulatory
authorities, referring physicians
• Resources available to manage complicated recipients
• Collective experience of the program – especially recent
similar cases
• Who is at the candidacy review meeting
• Allocation system itself – patients unlikely to get transplant
are not listed
21. Before listing – the referral decision!
• Not all patients are equally likely to be referred
• Geography – eg. in Canada – Telemedicine helps
• Referring physician beliefs about transplant,
willingness to assist with post-transplant care
• Patient social support, finances, insurance coverage
• Disadvantaged groups in every country
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22. Types of allocation systems
US LAS
1. Geography
2. Medical urgency
3. Post-transplant survival
“Rest of World”
1. Geography- to a variable extent
2. Clinical judgment includes urgency and
outcomes; urgency predominates
3. May incorporate values – restrict to residents,
preference to organ donors (Israel)
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24. How do allocation systems
stack up? US Others
++ + to +++
No ?
No +/-
Non-US +/-
restricted
++ +/-
+ ++
+++ + to +++
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25. Comparing Allocation Systems
US LAS “Rest of world”
• Pros • Pros
• Transparent • Allows for clinical judgment
• Explicit balance of urgency • May consider donor factors
and utility • May consider quality of life
• Cons • Cons
• Predictive value of LAS model • Geographic restrictions may
– is clinical judgment better? limit utility
• No consideration of donor • Opaque “black box”
factors • Considerations not explicit,
• No consideration of quality of may be subjective
life
• Geographic restrictions limit
utility
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26. Limitations of all lung allocation systems
• Single vs. bilateral transplantation – balance
between individual benefit and collective
utility, policies and practices inconsistent
• How to deal with quality of life?
• Geographical issues not resolved
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27. Towards an ideal allocation system - ideas
• Start with improving access to referral and maximizing
utilization of donor lungs
• Improve consistency of listing process – how?
• Use survival model scores as an aid to allocation rather
than a means?
• Model quality-adjusted survival benefit?
• Document candidates considered and allocation criteria
used for later review and audit?
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28. Summary
• LAS has decreased wait list mortality without significant adverse
impact on post transplant outcomes
• Differential access to donor lungs begins well before allocation
• No system is perfect
• All allocation systems involve tradeoffs
• Recognition of tradeoffs and biases is essential in developing
improved systems which maximize benefit of donor lungs
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