Organ Procurement and Transplantation Assessing Current Policies and the Potential Impact of the DHHS Final Rule (1999) / Chapter Skim
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5 Analysis of Waiting Times
5 Analysis of Waiting Times
Pages 61-90
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From page 61... ...
Large differences among organ procurement organizations (OPOs) in median waiting times for transplantation have been given as evidence that needier patients in one OPO may be left waiting while less needy patients in another OPO are receiving organs sooner.
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From page 62... ...
used regional differences In median waiting times for all patients combined as a basis for claiming that inequities exist In the allocation of organs to transplant patients. Panel 1 of Figure 5-1 illustrates the differences in median waiting times among He 11 UNOS regions, grouped by quartiles, for all liver transplant candidates registered between January 20, 1998, and January 19, 1999.
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From page 63... ...
~I. /~ Quardle 0-10 1 ~ N/A FIGURE 5-1 Median waiting times for liver transplantation, all status groups, registrations added January 20, 1998 to January 19, 1999.
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From page 64... ...
64 ~ ORGANPROCUREMENTAND TRANSPLANTATION Ye ~ Panel 3 T \ ~ ,-~'7 i ~De Ida ~ ~ ~ 0 - 10 : . ;; .: 11 - 50 1 1 NtA in Quartile I ::.: ~ :::: :~;.1: 11 - 50 FIGURE 5-1 Continued Panel 4 A, Do 2 0
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From page 65... ...
ANAL YSIS OF WAITING TIMES [IGURE 5-1 Continued 65 Panel 5 Id, ~ I, -p ~' ; Quartile __ 51 - 150 150 ~ N/A it\ ~I ADD
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From page 66... ...
Because of the large differences in waiting times by status, analyses were performed separately for status levels 1, 2B, and 3. (There were insufficient data to evaluate waiting time in status 2A.)
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From page 67... ...
Conceptually, the model allows evaluation of the competing risks of transplantation and pretransplantation mortality over time as a function of certain variables such as age, gender, race, blood type, and volume of transplants in OPOs. A further distinguishing feature of the model is that it allows for an analysis of OPO-specific rates for transplantation and pretransplantation mortality by representing OPO as a random effect.
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From page 68... ...
Overall, the committee found reasonable equity among OPOs in terms of waiting time for transplantation and in pretransplantation mortality for (status 1) patients, but greater variation in waiting times for patients in statuses 2B and 3.
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From page 69... ...
Additional detail is provided in Table B-1 in Appendix B which presents average waiting times, transplantation rates, pre- and posttransplantation mortality rates, and demographic information for status 1 patients for each OPO, sorted by the number of status 1 patients in the OPOs.
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From page 70... ...
Moreover, the observed large variations In waiting times for all patients, regardless of status, disguise the narrow variations within Me status 1 category. Thus, looking only widen the category of Me most severely ill patients (status 1)
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From page 71... ...
(0.172) Waiting time 0.023a -0.213 *
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From page 72... ...
, average waiting times range from 40 to 70 days, with greater variability across OPOs than was seen for status 1 patients. In general, smaller-volume OPOs appear to have somewhat higher transplantation rates for their status 2 patients.
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From page 73... ...
and cumulative time-event distribution (b) for status l patients awaiting liver transplantation.
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From page 74... ...
, average waiting times on the order of 100 to 400 days are much greater in variability across OPOs relative to statuses 1 and 2B patients. The tendency for smaller-volume OPOs to have somewhat higher transplantation rates, which was observed for status 2B patients, is even stronger for statuses 3 or 4 patients.
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From page 75... ...
0.20 0.18 0.16 0.14 012 ._ 0.10 0.08 0.06 0.04 0.02 0.00 1.0 O.g 0.8 0.7 0.6 0.52 0.4 0.1 Tmnsplan1 Death I ~ I ~ I ~ I ~ I ~ I ~ I ~ I ~ I ~ I ~ 2 3 4 5 6 7 8 g 10 11 12 Month ~n~l~ o.o 75 (a)
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From page 76... ...
By contrast, the intraclass correlation for pretransplantation mortality rates was not significant, once again indicating that the differences in transplantation rates across OPOs are not leading to differential mortality rates. To help illustrate these effects, Figure 5-4a displays the estimated hazard functions, and Figure 5-4b displays the estimated cumulative time-to-event distributions for transplantation and mortality rates over the first 12 months of status 3 listings.
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From page 77... ...
and cumulative time-event distribution (b) for status 3 patients awaiting liver transplantation.
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From page 78... ...
As discussed previously, under the current system, status 1 patients receive transplants at similar rates among OPOs and have similar mortality and outcomes. However, the equity of the current system, and its effectiveness in getting organs to the neediest patients, might be improved if it were possible to identify a minimum OPO population size or transplant volume that would promote both greater consistency in transplantation rates across OPOs and a higher rate of transplantation for patients with the greatest medical need.
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From page 79... ...
(0.604) Waiting time -0.003a -0.105 *
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From page 81... ...
Figure 5-7b displays a similar graphic for pretransplantation mortality rates and, again, there is a much smaller effect of OPO size. At 1 month the mortality rate is approximately 1 to 1.5 percent, at 4 months the rate is approximately 0.5 to 1 percent, and at 12 months the mortality rate is approximately 0.1 percent, regardless of OPO size.
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From page 82... ...
The marginal frequency of transplantation increased from 42 percent without sharing to 52 percent with sharing, with average waiting times of 4 and 3 days, respectively. Although the change was not statistically significant, pretransplantation mortality rates decreased from 9 percent without sharing to 7 percent with sharing.
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From page 83... ...
(b) FICL~ 5-6 A ~e-dimension~ view of me rel~icos~ps gong w~tingUi~ time (measured in monkish OPO population On -Hionst and prob~Hity of Plant (a)
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From page 84... ...
~0.06 C~ Cat 0.05 o o Q 0.04 0.03 nn2 not nns 0.04 Cut C) Cat 0.03 ._ co o CL O.01 ORGAN PROCUREMENT AND TRANSPLANTS TION Month -- 1- -- I - I: ,- ,/.
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From page 85... ...
sharing increases status 1 transplantation rates, (2) sharing decreases status 2B pretransplantation mortality rates, and (3)
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From page 86... ...
However, the overall differences among OPOs are somewhat underestimated by the intraclass correlations, which reflect OPO variability controlling for the effects of OPO size. Race and gender appear to play no significant role as predictors of transplantation rates and pretransplantation mortality rates.
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From page 87... ...
Smaller OPOs have lower transplantation rates per million people served, but even lower listing rates per million people served, relative to larger OPOs. The lower listing rates at small OPOs appear to permit these small OPOs to perform transplants on patients who are farther down the waiting list than do the larger OPOs, rather than reflecting greater efficiency.
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From page 88... ...
Statusspecific rates of pretransplantation mortality and transplantation are more meaningful indicators of equitable access. Examination of status-specif~c average waiting times across OPO areas demonstrates that they are typically only about 3 - days for status 1 patients and 40-70 days for status 2 patients, compared to 100~00 days for status 3 patients.
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From page 89... ...
On the basis of the analyses in this report, it seems apparent that patients on liver transplant waiting lists will be beKer served by an allocation system that facilitates broader sharing within larger populations. RECOMMENDATION 5.1: Establish Organ Allocation' Areas for Livers The committee recommends that the DHHS Final Rule be implemented by the establishment of Organ Allocation Areas (OAAs)
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From page 90... ...
An appropriate medical triage system should be developed to ensure equitable allocation of organs to patients in these categories. Such a system may, for example, be based on a point system arising out of medical characteristics and disease prognoses rather than waiting times.
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