National Rates Table: Kidney
Explanation and context around the 5-tier assignments
|Cells contain Median (minimum - maximum) values within each tier.|
|Getting A Deceased-Donor Transplant Faster (transplants per 100 years of waiting)|| 7.7
(0.9 - 9.8)
(9.3 - 17.3)
(16.1 - 27.8)
(22.8 - 37.2)
(37.6 - 123.3)
|1-Year Kidney Survival (% with functioning transplant at 1 year)|| 90
(84 - 92)
(89 - 93)
(92 - 94)
(94 - 97)
(96 - 98)
Figure 1. National Rates table for adult kidney programs. Each cell of the table contains the median (minimum–maximum) expected survival for an average risk transplant performed at programs within the tier. NA: Not Assessed (if the entire row is NA) or Not Available if no programs received that rating during this evaluation cycle (if only 1 or a few cells in a row are NA).
The “National Rates Table” is shown above the search results table and is meant to provide context around the 5 possible tier assignments. The table shows predicted outcomes within each of the 5 tiers for the two outcomes metrics shown in the search results. The numbers within each cell represent the predicted outcome for an “average patient” at an “average program” within the tier along with the minimum and maximum values within the tier.
Note that survival on the waitlist is not displayed for kidney transplant programs within the search results. This metric is included for other organ types. After piloting a version of the website that contained the survival on the waitlist metric for kidney programs, it was recommended to remove it because kidney programs may not be caring directly for patients on their waitlist. Data on waitlist mortality can be found within the full program reports for kidney programs, but it is not included in the main search results table.
What is an “average patient”? Each patient that is transplanted at a program is unique, with some patients being sicker than other patients or having other characteristics that may influence their outcomes. The predictions shown in the table are based on an average risk patient as determined based on all patients included in the evaluation nationally. This is represented by the “median” value within each cell of the table.
What is an “average program” within each tier? Each program falls into 1 of the 5 tiers based on the algorithm SRTR uses to assign the tiers. However, there remains some variation within each tier, with some programs being, for example, a “low tier 3” and some being a “high tier 3”. We assume patients are transplanted at an average program within the tier to derive the median estimate within each cell, rather than a program near the high or low end of the tier.
What do the minimum and maximum values represent? SRTR first determines the risk profile for an “average risk” patient and then assumes that patient is transplanted at an average program within each of the 5 tiers. This allows us to calculate one number within each cell of the table.
How are the numbers within each cell determined? SRTR first determines the risk profile for an “average risk” patient and then assumes that patient is transplanted at an average program within each of the 5 tiers as well as the lowest-ranked program within the tier and the highest-ranked program within the tier. This allows us to calculate one number within each cell of the table.
Why do the ranges (minimum – maximum) sometimes overlap across tiers? The tiers are assigned using a complex algorithm that takes into consideration each program’s outcomes as well as how certain we are of each program’s estimated performance. Therefore, it is possible to have programs with the same estimated outcomes, but one is rated in a different tier than another due to the level of certainty with which we made the estimate. This can result also result in, for example, a program at the high end of a tier having better estimated outcomes than a program at the low end of the next tier up, e.g., a high-3 may have better estimated outcomes than a low-4. Because the high-3 was estimated with less precision, it was assigned a lower tier.
Example interpretations of the table shown above:
Row 1: Getting A Deceased-Donor Transplant Faster (transplants per 100 years of waiting)
Here we see that if an average risk patient was transplanted at an average program in Tier 1 (the lowest rated programs), we would expect about 8 transplants from a deceased donor for every 100 years of waiting. Compare this with outcomes at an average program in Tier 5 (the highest rated programs) where we estimate 49 transplants from a deceased donor for every 100 years of waiting. These transplant rates would both be higher/lower for patients of higher/lower allocation priority than an “average” patient, but provide some context to the tier rating.
Row 2: 1-Year Kidney Survival (% with functioning transplant at 1 year)
Here we see that if an average risk patient was listed at an average program in Tier 1 (the lowest rated programs), we would expect about 90% survival with a functioning transplant at 1 year. Compare this with outcomes at an average program in Tier 5 (the highest rated programs) where we estimate 97% survival with a functioning transplant at 1 year. These first-year success rates would both be higher/lower for patients of higher/lower risk than an “average” patient, but provide some context to the tier rating.
Frequently Asked Questions (note: numbers in the FAQs are for illustrative purposes only)
I see a program with 98% first-year survival, which is higher than the 97% predicted survival for a tier 5 program, yet this program is rated a tier 3?
The tier assignments are based on performance relative to expected outcomes at the program based on the types of patients they list or the types of transplants they perform. Therefore, one cannot directly compare observed survival percentages (or waitlist mortality rates or transplant rates) with the expected outcomes within the tiers. Perhaps the program with 98% actual survival was transplanting lower risk patients and therefore had 98% expected survival. With 98% observed survival compared to 98% expected survival, the Tier 3 rating is appropriate given the program was performing as expected.
I see a program with 100% survival at 1-year following the transplant, but they are rated a tier 4 program. Why is this program not a tier 5 program?
The tier system is based on a comparison of observed outcomes to expected outcomes after taking into account the characteristics of the people transplanted at the program and the characteristics of the donor organs used. The tier methodology accounts for both the observed vs. expected outcomes at the program and the amount of information we have based on the number of transplants performed. For example, it would not be unusual for an average kidney program performing 10 transplants to have 100% survival given national first-year success rates of approximately 95%. Given 95% success rates nationally, we may not expect to see a failure until the program transplants at least 14 patients. Therefore, the tier system may show a tier 4 rating, which indicates some evidence of better than expected outcomes, but we do not have enough information to conclude the program is truly a tier 5 program. More successful transplants would need to be done to boost the program into the tier 5 rating. This also works in the other direction such that we need stronger information to conclude a program is a tier 1 program.