Presentation on theme: "Concentric Circle Liver Distribution Models"— Presentation transcript:
1 Concentric Circle Liver Distribution Models Julie Heimbach, MDTransplant surgeon, Mayo ClinicUNOS Liver Committee
2 Current Distribution Unit 58 OPO/Donor Service Areas PR & US VIDEMDMARIHIArbitrary, with wide variability in size, and population( million people.)
3 BackgroundDuring last year’s public comment period for broader sharing, multiple regions/individual public comments suggested looking instead at concentric circle model.This has been the long-standing model used in thoracic transplantation, modified in 2006 for hearts.
4 HEART ALLOCATION STATUSES Adult candidatesPediatric candidates1AMechanical circulatory support (MCS): VAD/30 days; TAH; IABP; ECMO;MCS with complications;Mechanical ventilationContinuous single high-dose or multiple IV inotropes with continuous hemodynamic monitoringVentilator;Mechanical assist device;Balloon pump;<6 months with reactive pulmonary hypertension >50% of systemic level;Single high-dose or multiple inotropes1BMCS beyond 30 days;Continuous IV inotropesSingle low-dose inotrope;<6 months old;Growth failure2All other active candidatesThere are multiple criteria for Status 1A and Status 1B; these are defined separately by age group. In addition to the specified criteria, there is an exception process for candidates with a comparable medical urgency who do not meet the stated criteria.
5 HEART DISTRIBUTION UNITS ZONE D:1500-<2500 milesZONE C:1000-<1500 milesZONE B: 500-<1000 milesZONE A: < 500 milesLOCAL (DSA)Thoracic organs are distributed based on Zones, rather than a regional system as is done for abdominal organs. The local unit represents the donation service area of the OPO where the donor hospital is located. Beyond the local unit, geographic zones are determined based on concentric circles from the donor hospital. For example, Zone A includes all candidates at transplant centers within 500 miles of the donor hospital but beyond the local DSA. Other zones are determined similarly based on increasingly larger concentric circles.ZONE E:>2500 miles
6 ALLOCATION ORDERING: Adult donors Local Status 1ALocal Status 1BZone A Status 1AZone A Status 1BLocal Status 2Zone B Status 1AZone B Status 1BZone A Status 2Zone B Status 2Zone C Status 1AZone C Status 1BZone C Status 2Zone D Status 1AZone D Status 1BZone D Status 2Zone E Status 1AZone E Status 1BZone E Status 2Prior to the policy modification, a heart from an adult donor would be offered to all local candidates prior to being offered out to Zone A. Now only local Status 1A or 1B candidates receive offers before hearts are offered to Zone A 1A or 1B candidates. The changes on July 12, 2006, are shown in yellow.The allocation ordering is a bit more complicated for pediatric donors, due to additional categories based on the candidate age and a recent change combining local and Zone A for some statuses. The current analysis focuses primarily on adult candidates and recipients so the pediatric allocation is not described in detail here.6
7 FOR DEATHS PER 100 PATIENT-YEARS ON THE WAITING LIST: Adult Candidates Status*Waiting era: 7/12/04-7/11/06Waiting era: 7/12/06-7/11/08# patients ever waiting# of deaths**Patient years (PY) at riskDeaths/100 PYSTATUS 1A2267233201.6115.62713205270.575.8STATUS 1B3254288827.234.83748217857.525.3STATUS 249362684421.26.143592223605.36.2ALL COMBINED77308115549.514.676216644811.913.8Death rates per 100 patient-years on the waiting list are shown for all adult candidates on this slide, both the overall rate as well as stratified by medical urgency status. These rates are based on a 2-year waiting period prior to the policy implementation and a 2-year period following the implementation.When looking at the overall (all statuses combined), the number of patients ever waiting during the two eras are very similar but the actual number of deaths is substantially lower, as is the number of patient-years waiting. When the deaths per 100 patient years is computed, you can see a decrease from 14.6 in the pre-policy era to 13.8 in the post-policy era.Next let’s look at the death rates within each medical urgency status. As expected, the death rate decreases with decreasing medical urgency (Status 1A to 1B to 2) regardless of era.It appears that there is a decline in mortality within Status 1A and Status 1B in the most recent era compared to the pre-policy era. The rate for Status 2 is almost identical in the two eras.* Inactive (status 7) is combined with the previous active status** Deaths include those reported to the OPTN or to SSDMF while on waiting list or within 7 days of non-transplant removal.7
8 NUMBER OF HEART TRANSPLANTS PERFORMED Transplant EraAge groupTOTALAdultPediatricPre-policy: 7/12/05-7/11/0619023242226Post-policy year 1: 7/12/06-7/11/0718873222209Post-policy year 2: 7/12/07-7/11/0818203312151The total number of heart transplants is similar over these three eras, but has decreased slightly in the two post-policy years.The number of pediatric transplants is almost identical in the 3 eras. Any decrease that has occurred is in the adult recipients. But this may be a function of a more frequent use of LVADs (after approval of the HeartMate II) or other medical therapies, rather than as a result of the policy modification.
9 ISCHEMIA TIME BY ERA FOR ADULT RECIPIENTS Number TXedN with ischemia timeMedian (minutes)5th and 95th %-ilesPre-policy: 7/12/05-7/11/061902178619294,293Post-policy year 1: 7/12/06-7/11/071887177520198,302Post-policy year 2: 7/12/07-7/11/0818201755199100,300Post-policy partial year 3: 7/12/08-3/11/091154107619797,308In spite of an increased number of transplants performed outside of the local area (from 36% to 45% on prior slide), the median ischemia time has increased only slightly for adults: from 192 minutes to minutes in the post-policy eras. The 95th percentile has also increased slightly for adults, from 293 minutes pre-policy to 308 minutes in the most recent era. (Only 5 percent of transplants have a longer reported ischemia time).
10 SURVIVAL WITHIN 1 YEAR: Adult recipients: All statuses combined We examined survival for a 20-month cohort transplanted pre-policy and a 20-month cohort post-policy. Post-transplant survival was almost identical in adult recipients in the two eras when all statuses were combined in spite of a greater percentage of transplants performed in Status 1A recipients. There was no statistical difference in these rates through 1 year. The survival rate at 1 year was 88% for both eras.Please note that the survival scale has been expanded (as it is on the following slide).NOTE: Scale of survival axis has been expanded.
11 SURVIVAL WITHIN 1 YEAR: Adult recipients: Status 1A at transplant Though the survival rate for adult recipients transplanted in Status 1A is slightly higher in the post-policy era, it is not statistically different from the pre-policy survival rate. The 1-year survival rates was 85% for the earlier era and 87% for the later era. Though not displayed here, the survival rates for recipients in Status 1B and Status 2 were also not significantly different pre- and post-policy.NOTE: Scale of survival axis has been expanded.
12 CONCLUSIONS The policy modification appears to be meeting its goals: Waiting list mortality has declined for adult candidates.A larger percentage of transplants are being performed in urgent candidates.Post-transplant survival has not been adversely affected.The results we have seen to date are consistent with the modeling predictions that were used in the policy development process.
13 Liver Concentric Circle Model: Using LSAM, the SRTR modeled a system using concentric circles for distribution units for all adult and pediatric donors.Additional runs were performed with sharing only for MELD > upper thresholds of 35, 32, 29, 25, and 22.
14 Methods Endpoints: deaths (pre and post) median distance traveled Study PopulationData from listed candidates and available donor organs from 1/1/2006 to 12/31/2006 were includedAnalytical ApproachLSAM was used to compare concentric circles for sharing above various MELD/PELD thresholds versus current. Results= average of 10 separate runs.Endpoints:deaths (pre and post)median distance traveled
18 Concentric Circles for Adult Deceased Donor Livers– February 2010 T:\slides\Liver-Intestine Committee\2009\ \LI_req_6637_v2.pptConcentric Circles for Adult Deceased Donor Livers– February 2010Concentric 250: 35 (29, 25, 22)0-250 NM – Status 1A then 1B0-250 NM – MELD/PELD 35 (29, 25, 22)NM – Status 1A then 1B0-250 NM – MELD/PELD (29, 25, 22)NM– MELD/PELD 35 (29, 25, 22)0-250 NM – MELD/PELD < 15500-1,000 NM – Status 1A then 1BNM – MELD/PELD (29, 25, 22)500-1,000 NM – MELD/PELD 35 (29, 25, 22)NM – MELD/PELD < 151,000+ NM – Status 1A/1B500-1,000 NM – MELD/PELD < 35 (29, 25, 22)1,000+ NM – MELD/PELDNote: NM = nautical mile radii (w/ donor hospital at the center)Created By:_MKG_______________ Date: _07/15/09__Contributing Analyst: _MKG_______ Date: _07/15/09__18
19 Concentric Circles: March 2010 T:\slides\Liver-Intestine Committee\2009\ \LI_req_6637_v2.pptConcentric Circles: March 2010Con (32, 29, 25, 22)0-250 NM Status 1ANM Status 1A0-250 NM Status 1BNM Status 1B0-250 NM MELD/PELD 35 (32, 29, 25, 22)NM MELD/PELD 35 (32, 29, 25, 22)0-250 NM MELD/PELD (31, 28, 24, 21)NM MELD/PELD (31, 28, 24, 21)NM Status 1ANM Status 1BNM MELD/PELD 151000+ NM Status 1A1000+ NM Status 1B1000+ NM MELD/PELD 150-250 NM MELD/PELD < 15NM MELD/PELD < 15NM MELD/PELD < 151000+ NM MELD/PELD < 15Note: NM = nautical mile radii (w/ donor hospital at the center)Created By:_MKG_______________ Date: _07/15/09__Contributing Analyst: _MKG_______ Date: _07/15/09__
20 Concentric Circles for Adult DD Livers: March T:\slides\Liver-Intestine Committee\2009\ \LI_req_6637_v2.pptConcentric Circles for Adult DD Livers: MarchFebruaryMarch Con (32, 29, 25, 22)0-250 NM – Status 1A, then 1B0-250 NM – MELD/PELD 35 (29, 25, 22)NM – Status 1A, then 1B0-250 NM – MELD/PELD (29, 25, 22)NM– MELD/PELD 35 (29, 25, 22)0-250 NM – MELD/PELD < 15500-1,000 NM – Status 1A500-1,000 NM – Status 1BNM – MELD/PELD (29, 25, 22)500-1,000 NM – MELD/PELD 35 (29, 25, 22)NM – MELD/PELD < 151,000+ NM – Status 1A1,000+ NM – Status 1B500-1,000 NM – MELD/PELD < 35 (29, 25, 22)1,000+ NM – MELD/PELD0-250 NM Status 1ANM Status 1A0-250 NM Status 1BNM Status 1B0-250 NM MELD/PELD 35 (32, 29, 25, 22)NM MELD/PELD 35 (32, 29, 25, 22)0-250 NM MELD/PELD (31, 28, 24, 21)NM MELD/PELD (31, 28, 24, 21)NM Status 1ANM Status 1BNM MELD/PELD 151000+ NM Status 1A1000+ NM Status 1B1000+ NM MELD/PELD 150-250 NM MELD/PELD < 15NM MELD/PELD < 15NM MELD/PELD < 151000+ NM MELD/PELD < 15Created By:_MKG_______________ Date: _07/15/09__Contributing Analyst: _MKG_______ Date: _07/15/09__20
21 Key differences Feb. to March: small circle for 1A, then 1B, then for MELD> 35 (or other).big circle for 1A, then 1B.back to the small circle for 15-35, then big circle >35(other), then to small circle for MELD <15.March:small circle 1A, then big circle for 1A.small circle 1B, then big circle for 1B.small circle >35 (or other lower), big circle >350-250 for 15-35, then , then national before for MELD <15.
22 Median Distance Between Donor Hospital and Transplant Center: February
23 Median Distance Between Donor Hospital and Transplant Center: March total increase mi
24 Decrease in Total Deaths (vs. Current) - February
25 Decrease in Total Deaths (vs. Current)- MarchOverall fewer deaths
26 Number of Transplants by MELD: March *More 1A, MELD >20. Overall ~110 fewer transplants.
27 Number of Deaths by Type: March *Overall ~ fewer deaths, slightly more post TX.
28 Number of WL Deaths by MELD- March T:\slides\Liver-Intestine Committee\2009\ \LI_req_6637_v2.pptNumber of WL Deaths by MELD- March*similar small decrease in WL death in each MELD groupCreated By:_MKG_______________ Date: _07/15/09__Contributing Analyst: _MKG_______ Date: _07/15/09__
29 SummaryAll of the two tiered concentric circle systems resulted in higher median distances traveled vs. current.The distance increased as the MELD score for the upper threshold was reducedAll of the two tiered concentric circle systems resulted in fewer total deaths compared to current allocation rules in the simulations.The decrease in the number of deaths ranged from 83 to 105.
30 Median Distance vs. Decrease in Total Deaths Reg Shr BenefitFive ZonesConcentric250_1525National250_1532250_152915/2515/29250_152215/2215/35250_1535Concentric 3515/32Shr Pos BenefitReg Shr MELD250_29250_22250_35250_25Shr35R,National 15ConcentricCurrent
34 Number of WL Deaths by MELD- Feb. T:\slides\Liver-Intestine Committee\2009\ \LI_req_6637_v2.pptNumber of WL Deaths by MELD- Feb.Created By:_MKG_______________ Date: _07/15/09__Contributing Analyst: _MKG_______ Date: _07/15/09__34