 |
 |
|
|||||
Transplant Statistics: Annual Report
Technical Notes and Analytic Methods
Graft and Patient Survival
Tables 1.11 and 1.12 present national one-year graft and patient survival for all organs by year of transplant from 1990 to 1999. Index 1.13 presents national graft and patient survival for all organs at three months, one year, three years, five years, and 10 years. Overall survival rates for liver-intestine, kidney-liver, and kidney-heart transplants are shown in Index 1.13. Due to their small number, there are no other specific survival tables for these transplants.
Organ-specific tables of graft and patient survival by recipient characteristics are presented in Table 6 and Table 7 of each of the organ-specific sections. For kidney and liver transplants, separate tables are presented for cadaveric and living donor transplants. For kidney-pancreas transplants, there are two sets of graft survival tables, one for kidney graft survival and one for pancreas graft survival.
Please keep in mind that the survival rate data presented here are not risk adjusted for the many factors that influence transplant outcomes. Therefore, it is incorrect to infer that the variables shown (e.g., donor age, recipient blood type) by themselves cause the outcomes shown.
The data are based on the OPTN TCR, TRR, and TRF forms. Data are subject to change based on future data submission or correction.
Cohorts
In an effort to reflect the most current survival outcomes and to ensure the availability of sufficient follow-up data, the Annual Report uses different two-year cohorts for the different survival periods. The years for the cohorts are the most recent years for which the particular survival period has elapsed by the end of 2000, as shown below:
Please note that the center-specific survival tables use 34 months rather than three years. Future center-specific survival tables will use three years.
Patient survival statistics for each organ are computed only for the first transplant of that type that a patient received and exclude subsequent transplants of the same type for that patient. For kidney-liver, kidney-heart, and liver-intestine, patients who have had a previous transplant of either organ were excluded. For kidney-pancreas, patients who have had a previous simultaneous kidney-pancreas transplant only are excluded. Similarly, for heart-lung, patients who have had a previous simultaneous heart-lung transplant only are excluded. Graft survival statistics do not exclude these patients.
In order to present survival rates for the most prevalent types of procedures, the transplant cohorts used for these analyses excluded a number of higher risk or more unusual procedures. Living donor transplants were excluded for all but the living donor kidney and living donor liver transplant tables. Multi-organ transplants were excluded from the organ-specific tables with three exceptions: kidney-pancreas and heart-lung transplants are shown in separate tables, and intestine tables include intestine only and liver-intestine only transplants. Overall short- and long-term survival for kidney-liver, kidney-heart, and liver-intestine transplants are shown in Index 1.13. Heterotopic transplants were excluded for liver and heart transplants.
Patient and transplant procedure characteristics included in all the organ-specific tables are: recipient age, race, ethnicity, gender, blood type, previous transplant, U.S. residency, hospitalized at transplant, life support at transplant, donor age, and center transplant volume. For pancreas, the previous transplant characteristic includes tables for previous kidney and previous pancreas. For kidney-pancreas, the previous transplant characteristic includes previous kidney, previous pancreas, and previous simultaneous kidney-pancreas transplant.
For specific organs, additional factors are: PRA at transplant (kidney and kidney-pancreas), level of HLA mismatch (kidney, pancreas, and kidney-pancreas), relation of donor to recipient (living donor kidney, living donor liver), dialysis required during the first week posttransplant (cadaveric and living donor kidney), procedure type (heart and lung), and waiting list status at the time of transplant (liver and heart).
Factors not previously presented in the Technical Notes are described below.
Primary Diagnosis. The primary diagnosis of the disease causing organ failure applies to both transplant candidates on a waiting list and to transplant recipients. These data may be obtained from the waiting list, the TCR and/or TRR forms. Diagnosis categories for each organ type are broad classifications of the recipients' indications for transplant. Please note that there are no primary diagnoses listed for pancreas and kidney-pancreas transplants. This is because nearly all kidney-pancreas recipients have diabetes as their primary diagnosis. Tables 2.4 through 2.8 show the detailed diagnoses that are included in each broad category.
Donor Age. Donor age is obtained from the Donor Registration form. Delinquent or incomplete forms account for most unknown cases.
Center Volume. Center volume is calculated for each organ, center, and time period as the average number of transplants during the two calendar years included in the cohort of patients reported on for the time period. For each organ, centers are grouped into approximate quintiles by center volume (tertiles for intestine because of the small number of centers performing intestine transplants). Survival is then reported for patients in each group. For kidneys and livers, center volume includes both cadaveric and living donor transplants. All other living donor transplants are excluded. For all organs, center volume includes multi-organ transplants (including kidney-pancreas and heart-lung) which include the organ of interest. For example, a heart-lung transplant would contribute to the center volume count for hearts, lungs, and heart-lungs. For kidney-pancreas tables, center volume is calculated differently for the patient and graft survival tables. For patient survival, kidney-pancreas center volume includes only kidney-pancreas transplants and multi-organ transplants which include kidney-pancreas. For tables of kidney graft survival from a kidney-pancreas transplant, center volume is calculated as it would be for kidney and so includes kidney and kidney-pancreas transplants as well as other multi-organ transplants which include a kidney. For tables of pancreas graft survival from a kidney-pancreas transplant, center volume is calculated as it would be for pancreas and so includes pancreas and kidney-pancreas transplants as well as other multi-organ transplants which include a pancreas.
Dialysis in the First Week. For kidney transplants only, whether patients required dialysis within the first week posttransplant was collected from the TRR form. For these data, the cohorts used were restricted to transplants that did not fail within the first week posttransplant. In other words, the survival rates shown are conditional on the graft's functioning at least one week posttransplant.
Relation of Donor to Recipient. Relation of donor to recipient is shown only for living donor kidney and living donor liver transplants. The data currently are collected on the Living Donor Registration (LDR) Form. Delinquent or incomplete LDR forms account for most unknown cases.
The value N shown in each table represents the number of transplants for which a survival rate could be determined. This number may be different for graft and patient survival, due to the fact that patient survival includes only first transplants of that type, whereas graft survival includes all transplants. For graft survival, survival time for each transplant was calculated as the number of days from the date of transplant to the date of graft failure or death (if applicable) or the latest follow-up date reported. For patient survival, survival time for each transplant was calculated as the number of days from the date of transplant to the date of death (if applicable) or the latest follow-up date reported. Each of these tables also provides the standard errors (statistical measures of precision) along with each survival rate. Categories that include relatively few transplants generally exhibit large standard errors. This is an important consideration when comparing survival rates within the tables.
For completeness, all categories of demographic and medical factors were listed in the tables, including those with no transplants in the cohort (N=0). In categories that had zero to nine patients in the cohort, survival rates were not calculated and the symbol "*" appears.
The survival rate calculations were performed using the statistical procedure LIFETEST in version 8.1 of SAS (SAS Institute). Using LIFETEST, the survival rates were estimated using the Kaplan-Meier method (Kaplan), and standard errors were estimated using Greenwood's formula (Kalbfleisch).
Patients are followed until death or their last known date of follow-up for patient survival. In this report, patient follow-up is not linked across repeat transplants. This means that time at risk for patients whose grafts fail will be censored at the last follow-up date reported for the original organ. Previous editions have handled patient survival in a similar way (i.e., not linking across transplants). In this 2001 AR, patients are followed only from their first transplant of the organ. In previous reports, patients with re-transplants were entered into the analysis again at the start of the second or later transplant. Ideally, patients would be followed to death from first transplant of the organ type regardless of transplant failure or subsequent transplants. The current method overestimates survival because the death rate is higher after graft loss than with a functioning transplant.
A major problem with the current analysis is that the database does not include all the deaths for patients who died after graft failure. Centers are required to follow patients for two years after graft failure. If the center reporting on the original organ does not continue to report on the patient or if it reports the patient as lost to follow-up after graft failure, then a death is likely to be missed. This is particularly important for kidney transplant patients since they may be kept alive on dialysis after a graft failure. Future analyses may use deaths from the Social Security Death Master File to supplement the current OPTN/SRTR data to allow for the calculation of more complete patient survival statistics. In addition, for patients with a failed kidney transplant, dialysis information from CMS may be used as an indication that the patient is alive.
Center-Specific Reports | OPO Reports | National Reports | Data Accuracy | Report Timeline
Home | Who We Are | What We Do | About Transplants | Transplant Statistics | Research Resources | Contact Us | Site Map
SRTR Site designed and maintained by Diamond Bullet Design & URREA.