Tutorial

This tool was created to help patients in need of a liver transplant, their families, and their care teams understand the experiences of patients on a liver transplant program's waiting list in the recent past. To accomplish this, the tool uses actual patient experiences over the past 2 years. The tool takes a snapshot of each program's waiting list on a series of days within the 2-year period, then determines what happened to all of the candidates on that waiting list during the next year. At various time points during the year (30 days, 60 days, 90 days, 180 days, and 365 days) the tool determines how many patients successfully underwent transplant, how many died before undergoing transplant or were removed from the waiting list because they became too sick to undergo transplant, how many received a liver from a living donor, how many were removed from the waiting list for other reasons, and how many are still alive and waiting for a transplant. (Note: For a more thorough explanation of how the estimates were obtained and the calendar days on which the tool took a snapshot of the national waiting list, please refer to the Methodology tab.)

Step 1: Choose a transplant program

The tool is designed to provide information for each liver transplant program in the United States. To simplify selection of a liver program, users first narrow the selection options by state. Once a state is selected, all liver transplant programs in that state are shown. Only programs with least one active adult patient on the waiting list on the days the snapshots were taken are shown.

Step 2: Choose your blood type (optional)

Users may narrow results by blood type. Blood type affects access to transplant because some blood types are more common than others in the general population. Compatible livers are more available to waiting candidates with common blood types and less available to those with rarer blood types. Selecting a blood type can greatly reduce the number of patients available to study at each program, often making good estimates difficult to derive. If fewer than five patients are available to study, the tool will not display results. If this happens, users may still be able to see results for all programs in their local area, the region, or nationally. This is the reason the tool shows results at four levels: the selected program, all programs in the local area, all programs in the region, and all programs nationally.

Step 3: Choose your age group (optional)

Users may narrow results by broad age categories. While a candidate's age is not a factor in determining who receives a liver offer, selecting an age category can give results more tailored to the user’s age group. The tool allows selection of all adult candidates or of adults aged younger or older than 55 years.

Step 4: Choose a MELD score range

The model for end-stage liver disease (MELD) score is used to determine which candidates are sickest and most in need of a life-saving liver transplant. The MELD score is calculated from three laboratory test results (bilirubin, INR [prothrombin time], and serum creatinine). Scores range from 6 to 40, with higher scores representing sicker patients. The MELD score is generally the higher of the measured, or laboratory, MELD score or any exception MELD score the candidate has been granted (see step 5). The tool provides results for various ranges of MELD scores. For a user whose MELD score to determine priority (either the laboratory MELD or the exception MELD) is currently 32, selecting results for the MELD score range 30-34 will display results only for candidates with a MELD score within that range.

Step 5: Choose whether to view results only for patients with/without MELD exception scores

In certain circumstances, a candidate’s care team and the regional review board may determine that the severity of illness is not adequately represented by the laboratory MELD score. These candidates can be given exception MELD scores that are higher than their laboratory MELD score. The tool allows users to view results for all patients within the given MELD range, or only those patients with or without exception MELD scores. Whether a user has or has not been awarded exception points will influence which version of the results may be most useful.

Step 6: Choose the timeframe for which you would like to see results

The tool provides results for candidate outcomes at 30 days, 60 days, 90 days, 180 days, and 365 days. Users can choose which time frame to consider. The tool uses 24 daily snapshots to estimate the 30-day outcomes (about 1 day per month over a 2-year period). For longer time frames, the number of daily snapshots goes down. For a more thorough explanation, please refer to the Methodology tab.

Interpreting the results

The tool provides results for actual candidates on the liver transplant waiting list on the days when the snapshots were taken. Users can choose to view the results as a pie chart (Graphical Results tab) or as a table (Tabular Results tab). These displays provide identical information.

The first consideration is the number of candidates used to estimate the results. This is shown above each table or figure. If fewer than five candidates were available to study, the tool will not display results. Also, the number of candidates studied is not the same as the number of candidates on that program's waiting list on a given day. The number of candidates studied includes all candidates on the multiple days the snapshots were taken (up to 24 different days over a 2-year period), but only data for those meeting the criteria the user selected (blood type, age group, MELD score range) are displayed. Therefore, this number does not represent the full size of a program's waiting list.

The results displayed provide the number and percentage of candidates who experienced each outcome. The pie chart displays the percentages by default if the “slice” of data is large enough. Users can see all counts and percentages by hovering over specific slices of the pie chart. The tabular results display the numbers and percentages by default.

Consider the following hypothetical set of 30-day results from 150 candidates with MELD scores between 30 and 34 (any blood type and all adults combined):

• 35 (23%) underwent deceased donor transplant.
• 8 (5%) died or were removed from the list due to becoming too sick to undergo transplant.
• 3 (1%) underwent living donor liver transplant.
• 1 (< 1%) was removed from the list due to improved condition and transplant was no longer needed.
• 4 (3%) were removed from the list for other reasons.
• 99 (66%) were still on the waiting list.

For adult candidates with a current allocation MELD score between 30 and 34, these data indicate that 66% of candidates on the waiting list remained on the waiting list 30 days later, while 23% received a liver from a deceased donor, 5% died or were removed from the list because they became too sick to undergo transplant, 1% received a liver from a living donor, 1 patient experienced improved condition such that transplant was no longer necessary, and 3% were removed from the list for other reasons (undergoing transplant at another program, transferring to another program, undergoing transplant in another country, or no longer being reachable by the program).

The results are also displayed for three larger geographic areas. The local donation service area considers all candidates listed in the program's local area as defined by donation service areas (including the selected program). The OPTN region pools all candidates within the specific OPTN region (there are 11 national regions). And finally, the data for all patients nationally meeting the selected criteria are displayed.

Methods Used to Develop the Liver Waiting List Calculator

Version 1.5: released July, 2021

The liver waiting list calculator was developed to help liver transplant candidates and their doctors understand what may occur in the coming year. The tool uses historical data to show what happened to patients on the liver transplant waiting list within 30, 60, 90, 180, or 365 days. Possible outcomes include:

• Receiving a liver from a deceased donor.
• Receiving a liver from a living donor.
• Dying or being removed from the waiting list due to becoming too sick to undergo transplant.
• Being removed from the waiting list due to improved condition such that a liver transplant is no longer needed.
• Being removed from the waiting list for other reasons (undergoing transplant at another program, transferring to another program, undergoing transplant in another country, no longer being reachable by the program).
• Remaining on the waiting list.

In the United States, livers are generally allocated within a local area first, followed by regional, and then national. The allocation system attempts to give donated livers first to the sickest candidates who are nearby before offering them to a broader geographic area, in an effort to place the livers quickly and avoid long shipping times (for a brief summary of the liver allocation policy, click here, and for the full policy, click here).

The tool provides information at the following geographic levels:

• Transplant Program: First, the tool shows what happened to transplant candidates listed at the selected transplant program.
• Donation service area: Generally, donated livers are offered to candidates within a local area first, the donation service area (DSA). Each of the 58 DSAs in the United States is served by an organ procurement organization. If a DSA includes more than one liver transplant program, all candidates on each program's waiting list are combined to create one list and the donated liver is offered to the appropriate candidates on the list according to the current allocation policy.
• Organ Procurement and Transplantation Network (OPTN) region: If no candidates are identified within the local DSA, the liver will be offered to candidates within the broader OPTN region. There are 11 OPTN regions in the United States.You can find more information on OPTN regions here.
• National: If no candidates are identified within the OPTN region, the liver will be offered to candidates nationally.

(Note that the above description of local, regional, national allocation is a simplification of the actual policy. Please reference the actual allocation policy provided here for a complete understanding of the policy.)

The tool provides data for the four geographic regions so users can compare what occurs within the program, the DSA, the broader OPTN region, and the nation as a whole. If any specific grouping includes fewer than five candidates, the data will be suppressed. In these cases, data may be sufficient to allow estimates to be derived at the DSA level, OPTN regional level, or the national level.

The tool is built to display outcomes from any day on the waiting list, not only from the candidate's first day. A candidate's priority on the list is determined by the model for end-stage liver disease (MELD) score. The MELD score is calculated from serum creatinine, bilirubin, and INR values, and by whether the candidate received kidney dialysis within the past week. These factors result in a measured, or laboratory, MELD score. In addition, some candidates are awarded exception MELD scores due to other underlying conditions that warrant additional priority (e.g., certain types of liver cancer). The tool allows the user to narrow results by whether the candidate has or does not have an exception MELD score. Please consult your care team for more information regarding exception MELD scores.

The tool uses actual historic data to derive the results. A snapshot of the actual liver transplant waiting list was taken on 24 separate days within a 2-year period, each about 30-days apart. Candidates were followed for 30, 60, 90, 180, or 365 days to observe outcomes. In order to create non-overlapping observation windows for the varying outcomes studied, only certain days are included in the calculations for the various timeframes as indicated in the following table.

Adult (aged 18 years or older) candidates on the list on the above days were included in the analysis. Candidates who were currently Status 1A, the most critically ill, were excluded. Candidates listed at multiple programs were included separately, as if they were two different candidates; however, a transplant event was counted only toward the program in which the transplant took place. Thus, for a candidate listed at a program in New York and a program in Washington, DC, who underwent transplant at the program in Washington, DC, the tool counts the transplant event toward the program in Washington, DC. Candidates who were listed for more than one organ, e.g., a kidney and a liver, are included in the analysis. Liver-intestine candidates with additional priority were included as having exception MELD scores that reflect the additional priority. Results are presented as counts and percentages of all candidates meeting the selection criteria (blood type [optional], age group [optional], MELD score range, and exception MELD score status [optional]).

The tool is intended solely for informational purposes and is not meant to offer advice to candidates or their doctors as to the appropriate treatment for a specific candidate. Patients should always discuss their treatment options with their care providers.

Frequently Asked Questions (FAQs)

Q: I'm looking for information about a liver transplant program that is not shown on the tool. Why doesn't my program appear?
A: First, make sure you have selected the correct state in which your transplant program is located. If the program still does not appear, it's possible that no active adult candidates were on its waiting list on the days the snapshots were taken. The tool displays data only for programs with at least one adult candidate active on their waiting lists on the days studied. Click on the Methodology tab for a list of the days when snapshots of each program's waiting list were taken. Programs that serve only pediatric patients (aged younger than 18 years on the days studied) are not shown.

Q: I have chosen my program, but I don't see any results.
A: This is because fewer than five adult patients were on the program's waiting list on the days the snapshots were taken. If fewer than five candidates were available to study, the tool displays no information. This rule is applied at all four levels for which the tool supplies data: program, local area, region, and nation.

Q: I don't know my blood type; can I still use the tool?
A: Choosing a blood type is optional. If you do not know your blood type, simply select Any Blood Type. Selecting your specific blood type can provide results that are better tailored to your situation, but it is not necessary to use the tool.

Q: I don't understand the difference between candidates with and without exception MELD scores. Can you provide more information?
A: A brief explanation is provided on both the Tutorial and the Methodology tabs. In addition, a brief explanation of liver allocation policy is available here and the full liver allocation policy is available here. Your care provider can also assist you in understanding the MELD score and how it is used to determine priority for liver transplant.

Q: I am currently a status 1A patient; can I still use the tool?
A: The tool is designed to provide information for adult liver transplant candidates who are not currently status 1A. Status 1A candidates are the sickest candidates on the waiting list and receive the highest priority when donor livers become available. This tool is designed for candidates waiting under the standard MELD-based allocation system.

Q: I see that some pediatric transplant programs are included in the tool and some are not. How come?
A: The tool considers only adult liver transplant candidates who were active on the waiting list on the days when snapshots were taken. An adult candidate is defined as aged 18 years or older on the day the snapshot was taken. Because some candidates on pediatric transplant program waiting lists are aged 18 years or older, those programs may be included in the tool. Pediatric programs with no listed candidates aged 18 years or older on the days studied are not included in the tool.

Q: Why does the tool consider only adult candidates?
A: Liver allocation to pediatric candidates is slightly differently from allocation to adult candidates. Pediatric candidates aged 11 years or younger receive pediatric end-stage liver disease (PELD) scores rather than MELD scores, and all pediatric candidates can receive pediatric status 1A or pediatric status 1B status. To keep the tool simple, we designed it to consider only candidates aged 18 years or older. SRTR may explore ways to provide similar information for pediatric liver candidates in the future.

Q: Your tool is helpful, but limited in scope because I can only narrow results by blood type, age, and current MELD score. Why not allow users to select many more factors to narrow results to patients most like themselves, e.g., cause of liver disease, sex, race, etc.?
A: The tool was designed to provide results using actual experiences of candidates listed within the most recent 2-year period. Because of this, the more characteristics selected, the fewer candidates are available nationally to study. This may lead to too few patients nationally to provide any estimates. SRTR considered an alternative strategy to develop a statistical model to estimate what may happen to specific candidates on the waiting list based on many characteristics. If a statistical model is developed, many assumptions will inherently be made in the model itself, which may lead to results that are questionable, especially when trying to estimate results at a particular transplant program. While a modeling effort was considered, SRTR felt that displaying real historical data was preferable since the primary goal of the tool was to display results at the program level, rather than broad estimates based on national experience.

Q: The tool is helpful, but what I really want to know is how long I can expect to wait for my liver. Can you develop a tool to estimate how long I will have to wait?
A: Estimating how long any particular candidate will have to wait to receive a liver is very difficult given the many factors involved. By constructing this tool, we hope to provide information to candidates over a range of time periods out to 365 days. While the tool cannot predict how long an individual patient will wait, it can provide insights into the experience of patients over the past 2 years. Knowing that 55% of candidates at a program underwent deceased donor transplant within the subsequent 90 days can provide some insights into what might happen for a similar candidate in the next 90 days.

Q: I see an example where 40% of candidates underwent transplant within 60 days. Does this mean within 60 days of their first listing date?
A: Not necessarily. The tool is constructed by taking multiple snapshots of the list over a 2-year period. The tool looks at all candidates on the list on that day (regardless of how long they were on the list) and considers what happened to those candidates in the subsequent 30, 60, 90, 180, or 365 days. Therefore, one should not interpret the results to mean that this is what will happen from the day the candidate is added to the list, but rather what might happen from this day forward. A user of the tool who has been on the list for only 10 days at a MELD score of 32 can interpret the results similarly to a candidate who is currently on the list at a MELD score of 32 after having waited for 65 days.

Q: Will SRTR be developing similar tools for other organ types? A: Possibly. Allocation policies are different for every organ type, and different factors affect candidate priority on the list. These nuances require careful thought as to how such a tool is constructed and interpreted. SRTR worked with OPTN's Liver and Intestinal Transplant Committee during the development of this tool. We have worked on a similar concept with OPTN's Kidney Transplantation committee. Additional tools to help candidates, their families, and their care providers may be made available in the future.