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GLOSSARY
This glossary provides descriptions of some of the terms used in the Annual Report. For additional details, please see the Technical Notes.
ABO Blood Type. The classification of human blood into four groups: A, B, AB, and O. See Blood Type.
Actual Donor. A deceased donor with at least one organ recovered for transplantation who meets the criteria of an eligible death.
Acute Rejection. The host recognizes the graft as foreign and mounts an immunological attack on the graft tissues. Most acute rejections occur in the first year.
Additional Donor. A deceased donor who does not meet the criteria of an eligible death, such as one over 70 years old or one who falls into the category Donation After Cardiac Death, (DCD). Such a patient is not included in the calculation of the donation rate for hospitals.
Advisory Committee on Organ Transplantation (ACOT). Formed by the United States Department of Health and Human Services (HHS) in 2000 and comprising members appointed by the Secretary, the ACOT was established to provide additional input regarding HHS oversight of U.S. organ donation and transplantation activity and policies and their effect on patients.
Albumin. Albumin is a protein manufactured by the liver. Albumin is used in the PELD calculations as a measure of the severity of liver disease.
Allocation. The process of determining how organs are distributed. Allocation includes the system of policies and guidelines, which ensure that organs are distributed in an equitable, ethical, and medically sound manner.
Allocation Policies. Rules established by the OPTN to guide and regulate organ allocation and distribution in the United States.
Allograft. An organ or tissue that is transplanted from one person to another of the same species: i.e., human-to-human. Example: a transplanted kidney.
American Society of Transplantation (AST). Founded in 1982, AST is a membership organization of more than 2,200 transplant professionals dedicated to research, education, advocacy and patient care in transplantation. Our goal is to offer a forum for the exchange of knowledge, scientific information and expertise in the field of transplantation. AST is an OPTN member in the Medical Professional/Scientific Organization category whose president serves on the OPTN Board of Directors.
American Society of Transplant Surgeons (ASTS). A nonprofit membership organization of transplant surgeons. ASTS is an OPTN member in the Medical Professional/Scientific Organization category whose president serves on the OPTN Board of Directors.
Annual Death Rate. Calculated as the annual death rate per 1,000 patient years at risk. See Death Rate.
Antibody. A protein molecule produced by the immune system in response to a foreign body, such as virus or a transplanted organ. Since antibodies fight the transplanted organ and try to reject it, recipients are required to take anti-rejection (immunosuppressive) drugs.
Antigen. Any substance that causes the immune system to produce antibodies against it. An antigen may be a foreign substance from the environment. Examples include chemicals, bacteria, viruses, pollen, or foreign tissues. An antigen may also be formed within the body, as with bacterial toxins.
Anti-rejection Drugs (immunosuppressive drugs). Drugs that are used to prevent and/or treat rejection of a transplanted organ.
Arbor Research Collaborative for Health. [Formerly known as the University Renal Research and Education Association (URREA)] Located in Ann Arbor, Michigan, Arbor Research is a private, not-for-profit research organization established for the purpose of collecting information and conducting worldwide epidemiological, clinical, and economic studies of organ failure and related diseases. Its mission is to conduct research, to distribute information focused on improving patient care, and to provide analysis and research training opportunities for medical professionals. Arbor Research, in collaboration with the University of Michigan, is responsible for the administration of the Scientific Registry of Transplant Recipients (SRTR).
Association of Organ Procurement Organizations (AOPO). A national nonprofit organization of organ procurement organizations. AOPO is an OPTN member in the Medical Professional/Scientific Organization category whose president serves on the OPTN Board of Directors.
Asystole. The absence of contractions of the heart.
Beneficence. The principle of physicians and surgeons acting in ways that are reliably expected to result in a greater balance of clinical good over harm for their patients.
Benign. Not malignant.
Bilirubin. A breakdown product of hemoglobin from blood cells, the results of which are used in the MELD and PELD calculations as a measure of the severity of liver disease.
Biopsy (Bx). A tissue sample from the body, removed and examined under a microscope to diagnose for disease, determine organ rejection, or assess donated organs or tissues.
Blood Type. One of four groups (A, B, AB or O) into which blood is classified. Blood types are based on differences in molecules (proteins and carbohydrates) on the surface of red blood cells.
Blood Vessels. The veins, arteries and capillaries through which blood flows in the body. Certain blood vessels can be donated and transplanted.
Body Mass Index (BMI). A measure of body size, calculated as weight in kilograms divided by height in meters squared.
Bonferroni Technique. A conservative method for assigning significance when testing multiple hypotheses. The common threshold for statistical significance, a p-value less than 0.05, will generate a false positive when used on random data 5% of the time. Using this threshold to test many variables (even if the association is fundamentally random) is likely to result in at least one false positive. The Bonferroni technique adjusts the threshold of 0.05 by dividing it by the number of tests performed. See P-Value.
Brain Death. Irreversible cessation of cerebral and brain stem function; characterized by absence of electrical activity in the brain, blood flow to the brain, and brain function as determined by clinical assessment of responses. A brain dead person is dead, although his or her cardiopulmonary functioning may be artificially maintained for some time.
Cadaveric Donor. See Deceased Donor.
Candidate. A person registered on the organ transplant waiting list. When an organ is offered on behalf of the candidate, he or she is then referred to as a Potential Transplant Recipient (PTR).
Cardiac. Having to do with, or referring to, the heart.
Cardiac Death. Death resulting from the cessation of heart function; an individual who suffers a cardiac death can donate organs if the organs can be promptly cooled.
Cardiomyopathy. A weakening of the heart muscle or change in heart muscle structure that causes varying degrees of reduced heart function.
Censoring. Typically, a statistical term used in survival analysis to indicate an observation in which the outcome of interest has not yet occurred. For example, in a graft survival analysis, a transplant with a functioning graft may be censored at the last follow-up date because the graft is still functioning. Mathematically, censored observations are included in the analysis up to the point in time at which they are censored.
Centers for Medicare & Medicaid Services (CMS). Formerly the Health Care Financing Administration, CMS is an agency of the United States Department of Health and Human Services (HHS) responsible for administering the Medicare and Medicaid programs, which provide health care coverage to America's aged, disabled and indigent populations.
Chimerism. When one organism possesses cells with more than one genetic background, as in some transplant recipients.
Chronic. Developing slowly and lasting for a long time, possibly the rest of a person's life. For example, chronic kidney failure.
Chronic Obstructive Pulmonary Disease (COPD). A type of lung disease in which the lungs are damaged, resulting in difficulty breathing. The air passageways in people with COPD have become partly obstructed, impairing airflow in and out of the lungs. The air passageways also become clogged with mucus. A large percentage of COPD cases are caused by cigarette smoking; but there are other causes or contributory factors, such as chemicals and other lung irritants.
Cirrhosis. A disease of the liver in which normal, healthy tissue is replaced with nonfunctioning fibrous scar tissue, and healthy, functioning liver cells are lost; it usually occurs when there is a lack of adequate nutrition, an infection, or damage caused by alcohol abuse.
Cockcroft-Gault Formula. A calculation used as a measure of kidney function by estimating creatinine clearance. It is calculated from a patient's serum creatinine, age, weight and gender. For males: (140-age)*weight/(72*creatinine), where age is measured in years, weight is measured in kilograms and creatinine is measured in mg/dL. The same formula multiplied by 0.85 is used to estimate creatinine clearance for females.
Cohort. A group of individuals sharing one or more characteristics that are observed during a designated time period.
Cold Ischemia Time (CIT). The amount of time an organ spends being preserved after recovery from the donor.
Collaborative. A time-limited effort (usually 6 to 12 months) of multiple organizations that come together with faculty to learn about and to create improved processes in a specific topic area. The expectation is that the teams share expertise and data with each other, thus ″everyone learns, everyone teaches″.
Compliance. 1) Adherence of patients to medical advice and instructions, especially immunosuppressive drug schedules. 2) Adherence of OPTN members to the policies and bylaws of the OPTN.
Confidence Interval. In statistical analysis, sampling techniques are used to provide an estimate of some aspect of a particular population (i.e., the average age). This avoids having to take a census of the entire population. Because the estimate is based on a sample and not the entire population, the estimate is subject to error. A confidence interval provides a range of values about the estimate within which the true value (the value of the parameter based on the entire population) lies. The smaller the confidence interval, the more precise the statistical estimate.
Congestive Heart Failure (CHF). Any condition that causes the heart to lose its ability to pump blood efficiently. Fluid backs up in the lungs and may also accumulate in the legs.
Conversion, Conversion Rate. The percentage of times a death meeting eligibility criteria (eligible death) becomes an actual donor.
Coronary artery disease (CAD). The coronary arteries supply blood (and oxygen) to the heart muscle. When arteries are partially or completely obstructed, the blood and oxygen supply to the heart muscle is impaired. It is the most common cause of a heart attack.
Corticosteroid. A synthetic hormone used to reduce the body's normal immune reaction to infection and foreign tissue, such as a transplanted organ. Prednisone is a corticosteroid.
Cox Regression Model. A type of proportional hazards regression model widely used to analyze censored survival data. See Proportional Hazards, Censoring.
Creatinine. Found in the blood, it is a waste by-product of muscle; creatinine level in the blood is one of the key measures of kidney function.
Crossmatch. A blood test to determine compatibility between donor and recipient. A positive crossmatch indicates incompatibility. If the crossmatch is ″negative″, then the transplant may proceed. Crossmatching is performed for many organ transplants.
CUSUM. The cumulative summation (CUSUM) technique is used to evaluate changes in an outcome over time. This technique is being developed as a performance measurement tool that will be made available for transplant centers to use in monitoring posttransplant patient outcomes.
Cyclosporine. A drug used to prevent rejection of the transplanted organ by suppressing the body's defense system. It is considered an immunosuppressant.
Death Rate. The percentage of deaths observed in a group of patients, also referred to as the rate of mortality. In statistics, the death rate is calculated as the number of patient deaths observed per 1,000 patient years. Patient years are calculated based on the actual amount of follow-up time after transplant that recipients are studied.
Deceased Donor. An individual from whom at least one solid organ is recovered for the purpose of transplantation after suffering brain death or cardiac death.
Decoupling. The process of separating a pronouncement of death from a request for organ donation on the part of the deceased. The decoupling may involve a time delay as well as the use of different individuals when approaching a family.
Delayed Graft Function (DGF). A condition in which the transplanted organ does not function properly after the transplant. Many kidneys have a delay before they begin to function adequately. Kidneys can sometimes take as long as three to four weeks to achieve adequate function. When this occurs, a kidney recipient needs dialysis until the kidney starts to function.
Department of Health and Human Services (DHHS or HHS). The department of the federal government responsible for health-related programs and issues. Go to www.hhs.gov.
Diabetes. A disease in which the pancreas does not manufacture an adequate amount of insulin. As a result, the level of sugar in the blood is too high. A leading factor in heart and kidney failure.
Dialysis. A mechanical process designed to partially perform kidney functions, including correcting the balance of fluids and chemicals in the body and removing wastes. See Hemodialysis and Peritoneal Dialysis.
Direct Offer. An organ offer that is made by a host OPO directly to another OPO or a transplant center for a specific recipient.
Division of Transplantation (DoT). The office of the federal government whose principal responsibilities include the oversight of management of the Organ Procurement and Transplantation Network (OPTN), the Scientific Registry of Transplant Recipients (SRTR) and the National Marrow Donor Program (NMDP) contracts; public education to increase organ and tissue donation; and technical assistance to organ procurement organizations (OPOs). Go to www.hrsa.gov/osp/dot.
Domino Transplant. A procedure in which an organ is removed from one transplant candidate and immediately transplanted into a second patient, with the first patient receiving a new organ from a deceased donor.
Donation after Brain Death (DBD). Use of tissues or organs from a donor who has been declared brain dead.
Donation After Cardiac Death (DCD). Recovery of organs and/or tissues from a donor whose heart has irreversibly stopped beating, previously referred to as nonheartbeating or asytolic donation.
Donation Rate. In statistics, the number of actual donors where at least one organ is recovered for the purpose of transplant. One method of computing donation rate is as a percentage of a specified population (e.g., eligible deaths divided by donors recovered).
Donation Service Area (DSA). The geographic area designated by the Centers for Medicare & Medicaid Services (CMS) that is served by one organ procurement organization (OPO), one or more transplant centers, and one or more donor hospitals. Formerly referred to as Local Service Area or OPO Service Area.
Donor. Someone from whom at least one organ or tissue is recovered for the purpose of transplantation. A deceased donor is a patient who has been declared dead using either brain death or cardiac death criteria, from whom at least one vascularized solid organ is recovered for the purpose of organ transplantation. A living donor is one who donates an organ or segment of an organ for the intent of transplantation.
Donor Pool. A group of people eligible to donate an organ.
Donor Profile Index (DPI). A concept under discussion in review of kidney allocation enhancements, the Donor Profile Index is a continuous measure of organ quality based on clinical characteristics of the donor. This measure is similar to the Donor Risk Index (see below) but is scaled in relation to other organs to produce a percentile ranking.
Donor Registries. Available 24 hours a day, seven days a week, online registries provide authorized professionals access to a confidential database of registered organ donors, allowing easy and quick confirmation of an individual's consent to organ donation. All registries are voluntary and some are affiliated with the local motor vehicle bureau, while others are independently operated or OPO-based.
Donor Risk Index (DRI). A continuous measure of organ quality based on clinical characteristics of the donor.
Eligible Death. A heartbeating individual meeting, or imminently meeting, death by neurological criteria, aged 70 years or under, who has not been diagnosed with exclusionary medical conditions.
Eligible Donor. Any death or imminent death (ventilated and non-ventilated) reported by a hospital that is evaluated and meets organ donor eligibility requirements. Any patient aged 70 years or younger meeting death by neurological criteria, based on the American Academy of Neurology Practice parameters for determining brain death, who does not have any of the following indications:
End-Stage Liver Disease (ESLD). Irreversible liver failure that requires transplantation as hepatic replacement therapy.
End-Stage Organ Failure. The permanent need for organ replacement therapy. The option of transplantation exists for the failure of kidney, liver, heart, lung, pancreas, and intestine.
End-Stage Renal Disease (ESRD). Irreversible kidney failure that requires either dialysis or transplantation as renal replacement therapy.
Epidemiology. The branch of medicine that studies origins, control, and distribution of diseases within a population.
Ethnicity. In the SRTR database, race and ethnicity are now reported together as a single data element, reflecting the way these data are now collected. See Race for details.
Expanded Criteria Donor (ECD). A donor not considered to be ″ideal″ or ″standard″. A formal definition exists only for kidney donors: a deceased donor over the age of 60 years or a donor over the age of 50 years with two of the following: a history of hypertension, a terminal serum creatinine greater than 1.5 mg/dl, or death resulting from a cerebrovascular accident (stroke). While definitions do not exist yet for other organs, the characteristics of these nonstandard organs may include general or organ-specific factors such as advanced donor age, prior infection with hepatitis B or hepatitis C, a history of hypertension or diabetes mellitus, abnormal donor organ function, or nonheartbeating status of a deceased donor. The term ″expanded″ is used because an expansion of the donor pool is considered to increase transplantation; it is preferred to the term ″marginal″.
FEV1. Forced expiratory volume in one second (FEV1) is a measure of lung function. A decline in FEV1 is associated with worsening lung disease.
Final Rule. The Organ Procurement and Transplantation Network (OPTN) Final Rule (42 CFR Part 121) was issued and published in the Federal Register on April 2, 1998. This rule governs the operation of the OPTN and was amended (resulting from the Institute of Medicine's report Organ Procurement and Transplantation, 1999). The amended version was issued and published in the Federal Register on October 20, 1999. The Final Rule went into effect on March 16, 2000.
Fraction Transplanted (FT). A simple fraction of all waiting list registrants who received a transplant, regardless of the program where the transplant was performed. The FT summarizes the time to transplantation at any program among all registrants in that transplant program.
Geographic Units for Organ Distribution. The way that organs are allocated to individuals within geographic areas. With the exception of perfectly matched organs, donated organs are first offered to candidates within the designated service area (DSA) of the host organ procurement organization (OPO). If not accepted within the DSA of the host OPO, they are offered to transplant centers within the region, then to all centers across the nation.
Glomerular Filtration Rate (GFR). The rate at which the kidney filters blood. The GFR decreases with age and disease.
Graft. In the context of transplantation, a graft is an organ or tissue transplanted from one individual to another of the same species (e.g., human to human).
Graft Survival. Continued functioning of a transplanted organ, usually expressed as a measure of time since transplantation.
Haplotype. One of a pair of three linked tissue-matching genes that are usually inherited as a unit.
Hazard Ratio. A relative change in risk of an event (e.g., death) associated with either a 1-unit increase in a covariate (for continuous covariates) or for the group of candidates identified by the covariate relative to a reference group (for categorical covariates). In the Cox regression model, hazard ratios greater than 1 indicate increasing risk.
Health Insurance Portability and Accountability Act (HIPAA). Passed in 1996, HIPAA requires employers to provide health insurance coverage to employees who lose or change jobs, and includes an administrative simplification section which deals with the standardization of healthcare-related information systems including data security, protection of patient confidentiality and privacy. The Act mandates standardized formats for all patient health, administrative, and financial data; unique identifiers (ID numbers) for each healthcare entity, including individuals, employers, health plans and health care providers; and security mechanisms to ensure confidentiality and data integrity for any information that identifies an individual.
Health Resources and Services Administration (HRSA). HRSA, an agency of the United States Department of Health and Human Services (HHS), is charged with oversight of the Healthcare Systems Bureau, which in turn provides oversight to the Division of Transplantation (DoT). The mission of HRSA is to improve the nation's health by assuring equal access to comprehensive, culturally competent, quality health care for all. The goal is to assure total access health care and to eliminate health disparities for all Americans. HRSA supports a nationwide network of community and migrant health centers and primary care programs for the homeless and residents of public housing, serving more than 8 million Americans each year. HRSA also works to build the health care workforce and maintains the National Health Service Corps, oversees the nation's organ transplantation system, helps provide health resources for medically under-served populations, works to decrease infant mortality and improve child health, and provides services to people with AIDS through the Ryan White CARE Act programs.
Hemodialysis. A treatment for kidney failure in which the patient's blood is passed through a filtering membrane to remove excess fluid and wastes.
Hemoglobin (Hgb). The protein in red blood cells that carries oxygen.
Hepatitis.A viral infection or non-specific inflammation of the liver that can lead to liver failure. Hepatitis C is the leading cause of liver failure that leads to transplantation.
Hepatitis B Virus (HBV). Formerly called serum hepatitis, it is caused by the hepatitis B virus (HBV). About 10% of cases progress to chronic hepatitis. It is spread through intravenous drug use, through sexual contact with infected individuals, through exposure to infected body fluids, and vertically from mother to child. Common symptoms include abdominal pain, fatigue, fever, jaundice, and elevated liver enzymes. A vaccine against HBV is available.
Hepatitis C Virus (HCV). A form of hepatitis caused by the hepatitis C virus (HCV), previously known as non-A, non-B hepatitis.
Heterotopic Transplant. Transplantation of an organ to a site that is different from the location that the organ would ordinarily occupy within the body.
Histocompatibility Antigens. See Human Leukocyte Antigen System (HLA System).
HLA Mismatch (MM). In transplantation, a mismatch indicates the donor has at least one HLA-A, HLA-B, or HLA-DR antigen that is not present in the recipient. See Human Leukocyte Antigen System (HLA System).
Human Leukocyte Antigen System (HLA System). Human leukocyte antigens (HLA), also known as histocompatibility antigens, are molecules found on all nucleated cells in the body. Histocompatibility antigens help the immune system recognize whether a cell is foreign to the body. These antigens are inherited from one's parents. Human leukocyte antigens are used to determine the compatibility of kidneys and pancreata for transplantation from one individual to another. The major groups of HLA antigens are HLA-A, HLA-B, and HLA-DR. The values shown are based on the six HLA antigens (two each for the A, B, and DR loci) reported for both donors and recipients. Tables reporting the level of HLA mismatch indicate the number of HLA antigens found in the donor that are not shared by the recipients. In general, a smaller number of HLA mismatches yields better compatibility between donor organ and recipient.
Hypertension (HTN). High blood pressure. This condition occurs when the force of the blood pushing against the walls of the blood vessels is higher than normal because the blood vessels have either become less elastic or have gotten smaller. Hypertension causes the heart to pump harder to move blood through the body. It can cause kidney failure and heart disease if not treated.
Immunogenicity. The capacity of an antigen to stimulate an immune response.
Immunosuppression. The suppression of the immune response, usually with medications, to prevent the rejection of a transplanted organ or tissue. Medications commonly used to suppress the immune system after transplantation include corticosteroids, calcineurin inhibitors, antimetabolites, polyclonal antibodies, monoclonal antibodies, and TOR inhibitors, among others. A recipient's immunosuppressive regimen may include several different drugs, and it may vary depending on whether it is being used for induction, maintenance, or to treat a rejection episode.
Immunosuppressive. Relating to the weakening or reducing of the immune system's responses to foreign material; immunosuppressive drugs reduce the immune system's ability to reject a transplanted organ.
Induction Therapy. The administration of a brief course of high-dose immunosuppression in the early period following transplantation. Induction therapy precedes and overlaps with less intense long-term maintenance immunosuppression.
Informed Consent. The process of agreeing to accept a medical test, procedure, or treatment. Informed consent is based on (1) full disclosure of the nature, risks, and benefits of the intended medical intervention; (2) comprehension of the disclosed elements; (3) competence to make an independent decision; and (4) freedom from coercion to allow for a truly voluntary response.
International Normalized Ration (INR). A system established by the World Health Organization (WHO) and the International Committee on Thrombosis and Hemostasis for reporting the results of blood coagulation (clotting) tests. All results are standardized using the international sensitivity index for the particular thromboplastin reagent and instrument combination utilized to perform the test.
Inotropes. Medications that increase the force of contraction of the heart muscle.
Joint Commission. An independent, nonprofit organization that evaluates and accredits health care organizations and programs in the United States including hospitals, nursing homes and home health agencies. The commission establishes guidelines for the operation of hospitals and other health facilities and conducts survey and accreditation programs.
Justice. As applied to the medical ethics of transplantation, justice refers to allocation of organs to those patients in the most immediate need. Issues of justice are balanced by concerns of utility that, in this context, refer to allocating organs to those individuals who will make the ″best″ use of them. An example would be whether a potential recipient facing imminent death without a transplant but with a poorer chance of long-term survival should be given a transplant in preference to another individual with less immediate risk of death but a better long-term prognosis.
Kidney Allocation Review Subcommittee (KARS). A subcommittee of the OPTN Kidney-Pancreas Allocation Committee, created in 2004 to conduct a comprehensive review of the national system for allocating deceased donor kidneys, including a series of public hearings with expert testimony and open discussion focused on specific aspects of the national kidney allocation system and opportunities for assessment and/or improvement.
Kidney and Pancreas Simulated Allocation Model (KPSAM). A computer model that simulates the OPTN kidney and kidney-pancreas allocation systems for the assessment of the impact of various kidney policies.
Kidneys. A pair of organs that removes waste in the blood, resulting in the production of urine. Kidneys may be donated from both deceased and living donors.
Laparoscopic Surgery. A set of minimally invasive procedures for surgery in the abdominal and pelvic areas; it may be used for living kidney donors.
Leukocyte. A white blood cell.
Life-years. A total number of years lived within a certain population. Example: There were 10 transplant recipients, each lived 20 years following their transplantation. The posttransplant survival would be 200 life-years for these recipients.
Life Years From Transplant. The difference between expected years of patient survival with and without a transplant, based on the characteristics of the candidate and the donor − i.e., the estimated number of extra years of life that a transplant candidate could expect to gain from a kidney (or kidney-pancreas) transplant. This difference may be weighted by other factors − for example, to reflect quality of life differences for years spent with a functioning transplant versus years on dialysis.
List Exchange. A living kidney donor who does not have a compatible blood type with the intended recipient may offer his or her kidney to a stranger on the kidney waiting list; the originally intended recipient then advances on the waiting list. This practice is also known as living donor paired donation.
Liver. This organ aids in digestion and helps process proteins, carbohydrates, and fats. It also helps in storing substances such as vitamins. The liver produces bile and removes wastes from the blood. Both living and deceased donors can donate livers.
Living Donor. A living person who donates for transplantation an organ such as a kidney or a segment of the lung, liver, pancreas, or intestine. Living donors may be blood relatives, emotionally related individuals, or altruistic strangers. These may also include domino heart or liver transplants. See Domino Transplant.
Living Donor Paired Donation. The practice of two kidney recipients trading donors to avoid the problem of blood type incompatibility between recipient and intended donor.
Living Related Donor. A blood-related family member who donates an organ, which can include a kidney or part of a lung, liver, or pancreas, to another family member or relative. Examples include parent to child and sibling to sibling.
Living Unrelated Donor. A person not closely related by blood who donates an organ to another person; this can include a kidney or part of a lung, liver, intestine, or pancreas. Examples of this include husband to wife or friend to friend. Stranger-to-stranger living donations and transplants have become increasingly common within the past few years.
Lost to Follow-up (LTFU). Having no available data at some point following a particular event, such as the transplantation of an organ. Patients may become lost to follow-up in two different ways: (1) the transplant center reports them as being lost or (2) the center does not complete follow-up forms for a patient.
Lung Allocation Score (LAS). A measure used since 2005 to rank candidates for lung transplantations on the waiting list. A patient's LAS is calculated from estimates of survival probability while on the lung transplant waiting list and following transplantation.
Lungs. Respiration organs that aid in aeration of the blood. There is both a right and left lung that include two lobes each.
Match. The compatibility of an organ between a donor and a recipient. The greater the compatibility of the match, the more likely the transplantation will be successful.
Mechanical Circulatory Support. For patients with heart failure, a mechanical pump that is implanted into a patient to maintain blood circulation. See also Ventricular Assist Device (VAD).
Median Time to Transplant. See Time to Transplant (TT).
Median Waiting Time. See Waiting Time (WT).
Medical Urgency Status Codes. Each candidate on the liver, heart, and heart-lung waiting lists is assigned a status code that corresponds to how medically urgent it is that he or she receives a transplant. Medical urgency status for liver and heart is reported in the waiting list, recipient, and survival tables. The entries below present the definitions for each code, covering the last 10 years.
Medical Urgency Status Codes for Liver Allocation.
Pre-1997:
1 ICU-bound due to acute or chronic liver failure with a life expectancy of less than seven days without a liver transplant.
2 Hospitalized in an acute care bed for at least five days or ICU-bound.
3 Requiring continuous care.
4 At home.
7 Temporarily inactive.
1997:
In January 1997, Status code 4 was eliminated and all Status 4 patients were grandfathered into Status 3. In July 1997, an interim redefinition was given to Status 1 and Status codes 2A and 2B were introduced.
1 Age 18 or older with acute liver failure, with a life expectancy without a transplant of less than seven days, or less than 18 years of age and in ICU due to acute or chronic liver failure, with a life expectancy without a transplant of less than seven days. (See OPTN policies for a description of acute liver failure.)
2A In ICU due to chronic liver failure, with a life expectancy without a transplant of less than seven days.
2B Continuously hospitalized in an acute care bed for at least five days or ICU bound.
3 Requiring continuous care.
7 Temporarily inactive.
1997-2001:
1 Adult−Age 18 years or older with fulminant liver failure, with a life expectancy without a transplant of less than seven days.
Pediatric−Less than 18 years of age and in ICU due to acute or chronic liver failure, with a life expectancy without a transplant of less than seven days, and meeting other medical criteria. (See OPTN policies for a description of fulminant liver failure and for pediatric medical criteria.)
2A In a critical care unit due to chronic liver failure, with a life expectancy without a transplant of less than seven days and a long-term prognosis with a successful liver transplant equivalent to that of a patient with fulminant liver failure. Patient also has a Child-Turcotte-Pugh (CTP) score greater than or equal to 10 and meets other medical criteria. (See OPTN policies for a description of CTP score and other medical criteria.) This classification does not apply to pediatric patients, i.e., patients less than 18 years of age.
2B Age 18 years or older and has a CTP score greater than or equal to 10 or a CTP score greater than or equal to 7 and meets other medical criteria. (See OPTN policies for a description of CTP score and other medical criteria and for pediatric medical criteria.)
3 Requiring continuous care and, if age 18 years and older, has a CTP score greater than or equal to 7.
7 Temporarily inactive.
2002-2005:
1 Adult−Age 18 years or older with fulminant liver failure, with a life expectancy without a transplant of less than seven days.
Pediatric−Less than 18 years of age and in ICU due to acute or chronic liver failure, with a life expectancy without a transplant of less than seven days, and meeting other medical criteria. (See OPTN policies for a description of fulminant liver failure and for pediatric medical criteria.)
2006 and following:
1A Adult and Pediatric−Fulminant liver failure.
1B Pediatric−Mainly reserved for chronic liver failure.
Medical Urgency Status Codes for Heart Allocation.
Pre-1999:
1 (a) Patient requires cardiac and/or pulmonary assistance with one or more of the following devices in place: total artificial heart, left and/or right ventricular assist system, intra-aortic balloon pump, ventilator; (b) patient is in ICU and requires inotropic agents to maintain cardiac output; or (c) patient is less than 6 months of age.
2 All other active registrations.
7 Temporarily inactive.
1999 and following:
1A Adult−At least 18 years of age, with at least one of the following: (a) mechanical circulatory support for acute hemodynamic decompensation with a ventricular assist device (VAD) 30 days after being determined clinically stable (admittance to the listing hospital is not necessary for this criterion), total artificial heart (TAH), balloon pump, or extracorporeal membrane oxygenation (ECMO); (b) mechanical circulatory support for more than 30 days with objective medical evidence of significant device-related complications; (c) mechanical ventilation; (d) continuous infusion of a single high-dose intravenous inotrope or multiple intravenous inotropes, in addition to continuous hemodynamic monitoring of left ventricular filling pressures; or (e) the candidate is considered, using acceptable medical criteria, to have urgency and potential for benefit comparable to that of other candidates at this status.
Pediatric−Less than 18 years of age and meeting at least one of the following criteria: (a) requires assistance with a ventilator; (b) requires assistance with a mechanical assist device; (c) requires assistance with a balloon pump; (d) is less than 6 months old with congenital or acquired heart disease exhibiting reactive pulmonary hypertension at greater than 50% of systemic level; (e) requires infusion of high dose or multiple inotropes; or (f) meets none of the criteria specified above but has a life expectancy without a heart transplant of less than 14 days.
1B Adult−A registrant who (a) has a left and/or right ventricular assist device implanted for more than 30 days or (b) receives continuous infusion of intravenous inotropes.
Pediatric−A registrant who (a) requires infusion of low dose single inotropes, (b) is less than 6 months old and does not meet the criteria for Status 1A, or (c) exhibits growth failure (see OPTN policies for a definition).
2 A patient of any age who does not meet the criteria for Status 1A or 1B.
7 Temporarily inactive.
Medicaid. A partnership between the Federal government and the individual states to share the cost of providing medical coverage for recipients of welfare programs and allowing states to provide the same coverage to low-income workers not eligible for welfare. Programs vary greatly from state to state.
Medicare. A federal government agency that supports people aged 65 years and over, those who have permanent kidney failure, and certain people with disabilities by providing hospital and medical insurance, through Social Security taxes.
MELD Score. See Model for End-stage Liver Disease (MELD) Scoring System.
Membership and Professional Standards Committee (MPSC). The standing OPTN committee charged with insuring that OPTN members meet and remain in compliance with OPTN Criteria for Institutional Membership. The MPSC develops, modifies and makes recommendations to the board regarding criteria for institution membership and each class of membership to the Board, reviews membership applications and adopts recommendations to be presented to the Board; monitors members for compliance with membership criteria and policies including transplant center outcomes and activity levels and reviews reported policy violations and makes recommendations to the Board.
Mismatch. See Human Leukocyte Antigen System (HLA System).
Model for End-stage Liver Disease (MELD) Scoring System. A measure of illness severity used in the allocation of livers to adults, established in February 2002. The MELD system uses three laboratory values (bilirubin, creatinine, and INR) to calculate a score, on a scale of 6 to 40, that is predictive of the risk of death within three months on the liver waiting list. Livers are allocated to wait-listed patients with chronic liver disease on the basis of this score. See also Pediatric End-Stage Liver Disease (PELD) Scoring System.
Morbidity. A disease condition or the occurrence or rate of a disease within a population.
Mortality. The occurrence or rate of death within a population.
Multiple Listing. The act of being wait-listed at more than one transplant center.
National Organ Transplant Act (NOTA). The National Organ Transplant Act (1984 Public Law 98-507), approved October 19, 1984, and amended in 1988 and 1990, provided for the establishment of the Task Force on Organ Transplantation; authorized the Secretary of Health and Human Services (HHS) to make grants for the planning, establishment, and initial operation of qualified organ procurement organizations (OPOs); and established the formation of the Organ Procurement and Transplantation Network (OPTN) and Scientific Registry of Transplant Recipients (SRTR).
Nephrologist. A specialist in the treatment of kidney diseases and malfunctions.
Non-Directed Donation . Donation of organs from living donors who are not related to or known by the recipient.
Nonheartbeating Donor (NHBD). See Donation After Cardiac Death (DCD).
Notifiable Death. A subset of all in-hospital deaths that are aged 0-70 years and have no exclusionary medical diagnoses for possible donation. The number of notifiable deaths is based on methodology to determine the relevant subset of deaths in a geographic area, as described in Ojo et al., Transplantation, 1999.
Organ Donation. To provide an organ or a part of an organ to be transplanted into another person. Organ donation can occur with a deceased donor, who can give kidneys, pancreas, liver, lungs, heart, and intestinal organs, and with a live donor, who can give a kidney or a portion of the liver, lung, or intestine.
Organ Donation Breakthrough Collaborative. A program launched by the Health Resources and Services Administration (HRSA) in 2003 as part of the Department of Health and Human Services (HHS) Gift of Life Donation Initiative to (1) identify and promote the best practices in organ donation and procurement of hospitals and organ procurement organizations (OPOs) achieving the highest donation rates in the country and (2) raise the overall donor consent rate to 75% among participating hospitals and OPOs. A 4.3% increase in deceased donors occurred from 2002 to 2003, with donor consent increasing by 5%. The model for the Breakthrough Collaborative was based upon the best practice strategies developed by HRSA and the Institute for Healthcare Improvement.
Organ Preservation. Between procurement from a donor and transplantation into a recipient, organs require special methods of preservation. The length of time that organs and tissues can be kept outside the body varies, depending on the organ, the preservation fluid, and the temperature. See also Cold Ischemia Time (CIT) and Pulsatile Perfusion (PP).
Organ Procurement. The abstraction or recovery of organs from a donor for transplantation.
Organ Procurement and Transplantation Network (OPTN). Under a contract from the Health Resources and Services Administration (HRSA) and with oversight from the Division of Transplantation (DoT), the OPTN operates the national network for organ procurement and allocation and works to promote organ donation. Through its policies, the OPTN works to ensure that all patients have a fair chance at receiving the organ they need, regardless of age, sex, race, lifestyle, religion, or financial or social status. The current OPTN contractor is the United Network for Organ Sharing (UNOS), based in Richmond, Virginia.
Organ Procurement Organization (OPO). An organization designated by the Centers for Medicare & Medicaid Services (CMS) that is responsible for the procurement of organs for transplantation and the promotion of organ donation within a particular donation service area (DSA). There are currently 58 certified OPOs operating in the United States; each is a separate, private, nonprofit organization with its own board of directors. See also Donation Service Area (DSA).
Organs. Parts of the body made up of cells and tissues that have certain purposes and perform certain functions for the body. Solid organs that can be transplanted include hearts, lungs, livers, kidneys, intestines, and pancreata.
P-Value. The P value measures the statistical significance (or evidence) for testing a hypothesis. Usually, this hypothesis is either that two numbers are equal to each other or that a number is different from zero. A P-value of less than 0.05, indicating that there is less than a 5% chance that any observed difference occurred by random chance alone, is often considered "statistically significant."
Pancreas. An irregularly shaped gland located behind the stomach. The pancreas aids in the process of digestion of proteins, fats, and carbohydrates. The pancreas secretes insulin and other hormones that regulate blood sugar and insulin levels. Upon failure of the pancreas, an individual becomes diabetic.
Pancreas Transplant Alone (PTA). A type of isolated pancreas transplantation.
Panel Reactive Antibody (PRA). The PRA value is a measure of a patient's level of sensitization to human leukocyte antigens (HLA). It is the percentage of cells from a panel of blood donors against which a potential recipient's serum reacts. The PRA reflects the percentage of the general population that a potential recipient makes antibodies (is sensitized) against. The higher the PRA, the more sensitized a patient is to the general donor pool and, thus, the more difficult it is to find a suitable donor. A patient may become sensitized as a result of pregnancy, a blood transfusion, or a previous transplant.
Patient Survival. Patient survival refers to whether a transplant recipient is still alive at a certain time after transplantation.
Patient-years. This term is synonymous with life-years and refers to the total number of years lived by a group of people. It is sometimes used in rate calculations. For example, if 100 candidates each spent one year waiting for a transplant during a specified period and 50 were transplanted, the transplant rate for this group would be 50 transplants per 100 patient-years on the waiting list.
Pediatric End-stage Liver Disease (PELD) Scoring System. A measure of illness severity used in the allocation of livers to pediatric candidates, established in February 2002. The PELD system uses three laboratory values (albumin, bilirubin, and INR), a presence of growth failure (at least two standard deviations below average height or weight), and an indicator of whether the patient is less than 1 year of age to calculate a score predictive of the risk of death within three months on the liver waiting list for candidates under the age of 18 years. The range of PELD scores is greater than that of the model for end-stage liver disease (MELD) scores, ranging from less than zero to greater than 40. See also Model for End-Stage Liver Disease (MELD) Scoring System.
Percentile. The Nth percentile measure is the value at which N% of the cases are at or below that percentile. For instance, for liver waiting list registrations in 1998, the 25th percentile for waiting time was 140 days. This means that by 140 days after being added to the liver-transplant waiting list, 25% of registrants had been transplanted. For the same group, the median for waiting time was 390 days. The median is defined as the 50th percentile. For this group of liver registrants, 50% had been transplanted by 390 days.
Peritoneal Dialysis. A treatment technique for kidney failure that uses the patient's own body tissues inside of the abdominal cavity to act as a filter. The intestines lie in the abdominal cavity, the space between the abdominal wall and the spine. A plastic tube called a "dialysis catheter" is placed through the abdominal wall into the abdominal cavity. A special fluid is then flushed into the abdominal cavity and washes around the intestines. The lining (peritoneum) of the abdominal cavity and of intra-abdominal organs act as a filter between this fluid and the blood stream. By using different types of solutions, waste products and excess water can be removed from the body through this process.
Posttransplant lymphoproliferative disorders (PTLD). Abnormal accumulations of immune cells brought about by the immunosuppressive therapies used to prevent organ rejection.
Potential Donor. In terminology of the Association of Organ Procurement Organizations (AOPO), a patient who meets the criteria for brain death with no absolute contraindications to organ donation as defined by a standardized list from the International Classification of Diseases, Ninth Revision.
Pre-emptive transplant. A kidney transplant performed for a patient who never initiated dialysis.
Preservation. The process of keeping organs viable between procurement and transplantation.
Procurement. The process of donor screening and the evaluation, removal, preservation, and distribution of organs, tissues, or cells for transplantation.
Program-Specific Reports. SRTR program-specific reports include statistics about organ donation and recovery, waiting list activity such as transplant rate, and posttransplant outcomes such as graft and patient survival. These reports are published every six months with revised data about each organ procurement organization and transplant program operating in the United States.
Proportional Hazards. Covariates (e.g., in a regression model) have a multiplicative effect on the hazard (e.g., death rate) throughout the follow-up period.
Pulmonary. Having to do with, or referring to, the lungs.
Pulsatile Perfusion (PP). Preservation of kidneys using a machine that continuously circulates preservation solution rather than packaging the organs in a static iced preservation solution.
Race. In the SRTR database, race and ethnicity are now reported together as a single data element, reflecting the way these data are now collected (either race or ethnicity is required, but not both). Race here includes the following categories:
Recipient. A person who receives an organ or tissue transplant.
Recovery. The surgical procedure of removing an organ from a donor.
Referred Death. In OPTN terminology, this phrase includes all deaths or imminent deaths reported by a hospital to the organ procurement organization (OPO) within the donation service area (DSA).
Regimen. See Immunosuppression.
Regions. For the administration of organ allocation and appropriate geographic representation within the OPTN policy structure, the membership is divided into 11 geographic regions. Members belong to the Region in which they are located. The Regions are as follows:
Registrant. A candidate on the waiting list for an organ transplant.
Rejection. A phenomenon that occurs when a recipient's immune system attacks a transplanted organ, tissue, or cell. Immunosuppressive drugs help prevent rejection.
Renal. Having to do with, or referring to, the kidneys.
Retransplantation. The process of receiving another transplant due to rejection or failure of a transplanted organ.
Scientific Registry of Transplant Recipients (SRTR). The SRTR provides analytic support for the ongoing evaluation of the scientific and clinical status of solid organ transplantation in the United States. With oversight and funding from the Division of Transplantation (DoT), the SRTR is currently administered by Arbor Research Collaborative for Health (formerly URREA), in collaboration with the University of Michigan.
Sensitization. Potential recipients are ″sensitized″ if their immune system makes antibodies against potential donors. Sensitization usually occurs as a consequence of pregnancy, blood transfusions, or previous transplantation. The degree of sensitization is measured by panel reactive antibody (PRA). Highly sensitized patients are more likely to reject an organ transplant than are unsensitized patients.
Share 15. A component of liver allocation policy that became effective in January 2005. Under this policy, offers of livers are to be made to candidates with MELD scores of 15 or greater outside the procuring donation service area (but within the same region) if there are no local candidates with MELD scores of 15 or greater. Livers are allocated to local candidates with MELD scores of less than 15 only if there are no regional candidates with MELD of 15 or greater. See also Model for End-stage Liver Disease (MELD) Scoring System.
Standard Acquisition Charge (SAC). A fee paid by the organ procurement organizations (OPOs) directly to the transplant center for transplantation of deceased donor organs and for the costs of organ acquisition, hospitalization, and physician time.
Standard Criteria Donor (SCD) Kidney. A kidney donated for transplantation by a donor who has suffered brain death (i.e., not a donor after cardiac death) and who is not an expanded criteria kidney donor. See Donation After Brain Death (DBD), Donation After Cardiac Death (DCD) and Expanded Criteria Donor (ECD) Kidney.
Standard Error. The standard error measures the level of precision associated with the estimate of the mean of a population. Categories that include a large number of transplants generally have small standard errors, while categories with relatively few transplants generally have large standard errors. Survival rates associated with a smaller standard error are more precise than those associated with a larger standard error. Standard errors are presented in the graft and patient survival rates tables.
Status. An indication of the degree of medical urgency for patients awaiting heart or liver transplants. Examples: status 1A, status 1B, or status 2.
Steroid Avoidance, Steroid Withdrawal. Steroid avoidance is the practice of not using corticosteroids for immunosuppression following transplantation; steroid withdrawal is the practice of taking patients off corticosteroids for maintenance immunosuppression. These practices have evolved in response to concerns about adverse effects associated with steroid-based regimens.
Survival Rates. Survival rates indicate the percentage of patients who are alive and the grafts (organs) that are still functioning after a specified amount of time.
Thoracic Organs. Organs located in the chest, i.e., the heart and lungs.
Time to Transplant (TT).A measure of how long it takes until a wait-listed patient becomes transplanted, often reported in percentiles (e.g., 10th, 25th, median). TT considers all candidates who are initially registered on the waiting list and measures the time between waiting list registration and transplantation date. Of all the wait-listed patients in a cohort, half have been transplanted by the median TT; the other half may still be waiting or may have been removed for death or other reason. Among the factors affecting TT are the size of the waiting list; biologic issues such as blood type, body size of donors and recipients, panel reactive antibody (PRA), immunological factors, and medical urgency status (for liver and heart); donation rates within an area; donation request and consent procedures at organ procurement organizations (OPOs); and patient registration and organ acceptance practices at transplant centers. An alternative measure, waiting time, in which inactive time on the waiting list is not counted and patients are censored at any removal from the waiting list, may also be considered. Additional measures−such as the median of the waiting time among wait-listed patients and the median of the waiting time among actual transplant patients−are often used to measure similar concepts. See also Waiting Time (WT).
Tissue Type. An individual's combination of human leukocyte antigens. Matching for tissue type is used in kidney and pancreas transplantation. The tissue type for each patient on the waiting list is entered into a central computer maintained by the OPTN.
Transplant Center. A medical institution within the United States that operates an organ transplant program.
Transplant Program. Such programs are components of a transplant center. An individual transplant center may have programs for the transplantation of heart, lung, liver, kidney, pancreas, islets, and/or intestine.
Transplant Tourism. An informal term describing travel to a foreign country for the specific purpose of receiving an organ transplant.
Tumor. An abnormal growth of tissue resulting from an uncontrolled multiplying of cells that serves no physiological function. Tumors can be either malignant (cancerous) or benign (non-cancerous). Malignant tumors include newly developed or ″de novo″ solid tumors as well as recurrent tumors that had previously been treated. See also Posttransplant lymphoproliferative disorders (PTLD)
United Network for Organ Sharing (UNOS). Located in Richmond, Virginia, UNOS is a private, nonprofit membership organization that coordinates the nation's transplant system under the OPTN federal contract. UNOS assists the transplant community and the patients it serves by maintaining the national organ transplant waiting list, coordinating the matching and distribution of donated organs, increasing public awareness of the need for donated organs, serving as a forum to create and define organ-sharing policies that maximize the use of donated organs, producing professional education tools, and providing extensive information about organ transplantation to patients and the public.
United States Renal Data System (USRDS). The national data system that collects, analyzes, and distributes information about end-stage renal disease (ESRD) in the United States. The USRDS is funded by the National Institute of Diabetes and Digestive and Kidney Diseases. The USRDS collaborates with the Centers for Medicare & Medicaid Services (CMS), the OPTN, and the ESRD networks, sharing datasets and actively working to improve the accuracy of ESRD patient information.
Utility. As applied to the medical ethics of transplantation, ″utility″ refers to allocating organs to those individuals who will make the ″best″ use of them. Issues of utility are balanced by concerns for justice that, in this context, refer to allocation of organs to those patients in the most immediate need. An example would be whether a potential recipient facing imminent death without a transplant but with a poorer chance of long-term survival should be given a transplant in preference to another individual with less immediate risk of death but a better long-term prognosis.
Vascular. Referring to blood vessels and circulation.
Ventricular Assist Device (VAD). A mechanical pump that is implanted into a patient with heart failure to maintain blood circulation; it is used as a bridge to heart transplantation.
Waiting List (Active, Inactive, Removal). After evaluation by a team of transplant professionals, a patient is added to the national waiting list by the transplant center. Lists are specific to both geographic area and organ type: kidney, pancreas, kidney-pancreas, liver, intestine, heart, lung, and heart-lung. Each time a donor organ becomes available, a computer generates a list of potential recipients based on factors that may include genetic similarity, organ size, medical urgency, and time on the waiting list. Through this process, a new list that best matches a waiting patient to a donated organ is generated each time an organ becomes available.
Waiting Time (WT). A measure of how long it takes until a wait-listed patient becomes transplanted, often reported in percentiles (e.g., 10th, 25th, median). This statistic is calculated using the successive rates of transplantation seen at each time after registration, among candidates who remain active on the waiting list (dropping candidates when they die or are removed from the waiting list and excluding inactive times). This time is generally shorter than time to transplant (TT) for the same percentile since it uses transplant rates among those who remain active on the waiting list. The statistic measuring access to transplantation should not be confused with the accumulated waiting time that may be used for allocation purposes. See also Time to Transplant (TT).
Zero Antigen Mismatch (0MM). This occurs when the donor does not have any HLA-A, B, or DR antigens foreign to the transplant candidate.
