Glossary of clinical trials

A glossary of terms used in clinical trials.

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A

* Activities of daily living:: The tasks of everyday life. These activities include eating, dressing, getting into or out of a bed or chair, taking a bath or shower, and using the toilet. Instrumental activities of daily living are activities related to independent living and include preparing meals, managing money, shopping, doing housework, and using a telephone. Also called ADL. (NCI)

* Adverse effect:: An unwanted side effect of treatment. (NCI)

* Adverse event:: An unexpected medical problem that happens during treatment with a drug or other therapy. Adverse events do not have to be caused by the drug or therapy, and they may be mild, moderate, or severe. (NCI)

* Adverse reaction:: An unwanted effect caused by the administration of drugs. Onset may be sudden or develop over time (NLM)

* Advocacy and support groups:: Organizations and groups that actively support participants and their families with valuable resources, including self-empowerment and survival tools. (NLM)

* Animal model:: An animal with a disease either the same as or like a disease in humans. Animal models are used to study the development and progression of diseases and to test new treatments before they are given to humans. (NCI)

* Animal study:: A laboratory experiment using animals to study the development and progression of diseases. Animal studies also test how safe and effective new treatments are before they are tested in people. (NCI)

* Approved drugs:: In the U.S., the Food and Drug Administration (FDA) must approve a substance as a drug before it can be marketed. The approval process involves several steps including pre-clinical laboratory and animal studies, clinical trials for safety and efficacy, filing of a New Drug Application by the manufacturer of the drug, FDA review of the application, and FDA approval/rejection of application (NLM)

* Arm:: Any of the treatment groups in a randomized trial. Most randomized trials have two "arms," but some have three "arms," or even more (NLM)

B

* Baseline:* 1. Information gathered at the beginning of a study from which variations found in the study are measured. 2. A known value or quantity with which an unknown is compared when measured or assessed. 3. The initial time point in a clinical trial, just before a participant starts to receive the experimental treatment which is being tested. At this reference point, measurable values such as CD4 count are recorded. Safety and efficacy of a drug are often determined by monitoring changes from the baseline values. (NLM)

:* An initial measurement that is taken at an early time point to represent a beginning condition, and is used for comparison over time to look for changes. For example, the size of a tumor will be measured before treatment (baseline) and then afterwards to see if the treatment had an effect. (NCI)

* Best practice:: In medicine, treatment that experts agree is appropriate, accepted, and widely used. Health care providers are obligated to provide patients with the best practice. Also called standard therapy or standard of care. (NCI)

* Bias:* In a scientific research study or clinical trial, a flaw in the study design or the method of collecting or interpreting information. Biases can lead to incorrect conclusions about what the study or clinical trial showed. (NCI)

:* When a point of view prevents impartial judgment on issues relating to the subject of that point of view. In clinical studies, bias is controlled by blinding and randomization (NLM)

* Bioavailable:: The ability of a drug or other substance to be absorbed and used by the body. Orally bioavailable means that a drug or other substance that is taken by mouth can be absorbed and used by the body. (NCI)

* Bioinformatics:: The science of using computers, databases, and math to organize and analyze large amounts of biological, medical, and health information. Information may come from many sources, including patient statistics, tissue specimens, genetics research, and clinical trials. (NCI)

* Biological drug:: A substance that is made from a living organism or its products and is used in the prevention, diagnosis, or treatment diseases. Biological drugs include antibodies, interleukins, and vaccines. Also called biologic agent or biological agent. (NCI)

* Biometrics:: The science of collecting and analyzing biologic or health data using statistical methods. Biometrics may be used to help learn the possible causes of a disease in a certain group of people. Also called biostatistics and biometry. (NCI)

* Biometry:: The science of collecting and analyzing biologic or health data using statistical methods. Biometry may be used to help learn the possible causes of a disease in a certain group of people. Also called biostatistics and biometrics. (NCI)

* Biostatistics:: The science of collecting and analyzing biologic or health data using statistical methods. Biostatistics may be used to help learn the possible causes of a disease in a certain group of people. Also called biometry and biometrics. (NCI)

* Blind:: A randomized trial is "Blind" if the participant is not told which arm of the trial he is on. A clinical trial is "Blind" if participants are unaware on whether they are in the experimental or control arm of the study; also called masked. (NLM)

* Blinded study:: A type of study in which the patients (single-blinded) or the patients and their doctors (double-blinded) do not know which drug or treatment is being given. The opposite of a blinded study is an open label study. (NCI)

C

* Case report:: A detailed report of the diagnosis, treatment, and follow-up of an individual patient. Case reports also contain some demographic information about the patient (for example, age, gender, ethnic origin). (NCI)

* Case series:: A group or series of case reports involving patients who were given similar treatment. Reports of case series usually contain detailed information about the individual patients. This includes demographic information (for example, age, gender, ethnic origin) and information on diagnosis, treatment, response to treatment, and follow-up after treatment. (NCI)

* Case-control study:: A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition. For example, one group may have been exposed to a particular substance that the other was not. Also called a retrospective study. (NCI)

* Clinical:: Pertaining to or founded on observation and treatment of participants, as distinguished from theoretical or basic science. (NLM)

* Clinical investigator:: A medical researcher in charge of carrying out a clinical trial's protocol. (NLM)

* Clinical practice guidelines:: Guidelines developed to help health care professionals and patients make decisions about screening, prevention, or treatment of a specific health condition. (NCI)

* Clinical researcher:: A health professional who works directly with patients, or uses data from patients, to do research on health and disease and to develop new treatments. Clinical researchers may also do research on how health care practices affect health and disease. (NCI)

* Clinical series:: A case series in which the patients receive treatment in a clinic or other medical facility. (NCI)

* Clinical study:: A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called a clinical trial. (NCI)

* Clinical trial:* A clinical trial is a research study to answer specific questions about vaccines or new therapies or new ways of using known treatments. Clinical trials (also called medical research and research studies) are used to determine whether new drugs or treatments are both safe and effective. Carefully conducted clinical trials are the fastest and safest way to find treatments that work in people. Trials are in four phases: Phase I tests a new drug or treatment in a small group; Phase II expands the study to a larger group of people; Phase III expands the study to an even larger group of people; and Phase IV takes place after the drug or treatment has been licensed and marketed. (NLM)

:* A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease. Also called a clinical study. (NCI)

* Clinician:: A health professional who takes care of patients. (NCI)

* Cohort:* A group of individuals who share a common trait, such as birth year. In medicine, a cohort is a group that is part of a clinical trial or study and is observed over a period of time. (NCI)

:* In epidemiology, a group of individuals with some characteristics in common. (NLM)

* Cohort study:: A research study that compares a particular outcome in groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke compared with those who do not smoke). (NCI)

* Community-based clinical trial (CBCT):: A clinical trial conducted primarily through primary-care physicians rather than academic research facilities. (NLM)

* Compassionate use:: A method of providing experimental therapeutics prior to final FDA approval for use in humans. This procedure is used with very sick individuals who have no other treatment options. Often, case-by-case approval must be obtained from the FDA for "compassionate use" of a drug or therapy. (NLM)

* Compassionate use trial:: A way to provide an investigational therapy to a patient who is not eligible to receive that therapy in a clinical trial, but who has a serious or life-threatening illness for which other treatments are not available. Compassionate use trials allow patients to receive promising but not yet fully studied or approved therapies when no other treatment option exists. Also called expanded access trial. (NCI)

* Complementary and alternative therapy:: Broad range of healing philosophies, approaches, and therapies that Western (conventional) medicine does not commonly use to promote well-being or treat health conditions. Examples include acupuncture, herbs, etc. Internet Address: http://www.nccam.nih.gov. (NLM)

* Confidentiality regarding trial participants:: Refers to maintaining the confidentiality of trial participants including their personal identity and all personal medical information. The trial participants' consent to the use of records for data verification purposes should be obtained prior to the trial and assurance must be given that confidentiality will be maintained. (NLM)

* Consecutive case series:: A clinical study that includes all eligible patients identified by the researchers during the study registration period. The patients are treated in the order in which they are identified. This type of study usually does not have a control group. (NCI)

* Contraindication:: A specific circumstance when the use of certain treatments could be harmful. (NLM)

* Control:: A control is the nature of the intervention control. (NLM)

* Control animal:: An animal in a study that does not receive the treatment being tested. Comparing the health of control animals with the health of treated animals allows researchers to evaluate the effects of a treatment more accurately. (NCI)

* Control group:* In a clinical trial, the group that does not receive the new treatment being studied. This group is compared to the group that receives the new treatment, to see if the new treatment works. (NCI)

:* The standard by which experimental observations are evaluated. In many clinical trials, one group of patients will be given an experimental drug or treatment, while the control group is given either a standard treatment for the illness or a placebo (NLM)

* Controlled clinical trial:* A clinical study that includes a comparison (control) group. The comparison group receives a placebo, another treatment, or no treatment at all. (NCI)

:* An experiment or clinical trial that includes a comparison (control) group. (NCI)

* Controlled trials:: Control is a standard against which experimental observations may be evaluated. In clinical trials, one group of participants is given an experimental drug, while another group (i.e., the control group) is given either a standard treatment for the disease or a placebo. (NLM)

D

* Data and Safety Monitoring Board:* DSMB. An impartial group that oversees a clinical trial and reviews the results to see if they are acceptable. This group determines if the trial should be changed or closed. Also called DSMB. (NCI)

:* An independent committee, composed of community representatives and clinical research experts, that reviews data while a clinical trial is in progress to ensure that participants are not exposed to undue risk. A DSMB may recommend that a trial be stopped if there are safety concerns or if the trial objectives have been achieved. (NLM)

* Diagnostic trials:: Refers to trials that are are conducted to find better tests or procedures for diagnosing a particular disease or condition. Diagnostic trials usually include people who have signs or symptoms of the disease or condition being studied. (NLM)

* Dose:: The amount of medicine taken, or radiation given, at one time. (NCI)

* Dose-dependent:: Refers to the effects of treatment with a drug. If the effects change when the dose of the drug is changed, the effects are said to be dose-dependent. (NCI)

* Dose-limiting:: Describes side effects of a drug or other treatment that are serious enough to prevent an increase in dose or level of that treatment. (NCI)

* Dose-ranging study:: A clinical trial in which two or more doses of an agent (such as a drug) are tested against each other to determine which dose works best and is least harmful. (NLM)

* Dose-rate:: The strength of a treatment given over a period of time. (NCI)

* Double-blind study:* A clinical trial design in which neither the participating individuals nor the study staff knows which participants are receiving the experimental drug and which are receiving a placebo (or another therapy). Double-blind trials are thought to produce objective results, since the expectations of the doctor and the participant about the experimental drug do not affect the outcome; also called double-masked study. (NLM)

:* A clinical trial in which neither the medical staff nor the person knows which of several possible therapies the person is receiving. (NCI)

* Drug:: Any substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition. Also refers to a substance that alters mood or body function, or that can be habit-forming or addictive, especially a narcotic. (NCI)

* Drug-drug interaction:: A modification of the effect of a drug when administered with another drug. The effect may be an increase or a decrease in the action of either substance, or it may be an adverse effect that is not normally associated with either drug. (NLM)

E

* Efficacy:* The maximum ability of a drug or treatment to produce a result regardless of dosage. A drug passes efficacy trials if it is effective at the dose tested and against the illness for which it is prescribed. In the procedure mandated by the FDA, Phase II clinical trials gauge efficacy, and Phase III trials confirm it (NLM)

:* Effectiveness. In medicine, the ability of an intervention (for example, a drug or surgery) to produce the desired beneficial effect. (NCI)

* Eligibility criteria:* In clinical trials, requirements that must be met for an individual to be included in a study. These requirements help make sure that patients in a trial are similar to each other in terms of specific factors such as age, general health, and previous treatment. When all participants meet the same eligibility criteria, it gives researchers greater confidence that results of the study are caused by the intervention being tested and not by other factors. (NCI)

:* Summary criteria for participant selection; includes Inclusion and Exclusion criteria. (NLM)

* Empirical:: Based on experimental data, not on a theory. (NLM)

* Endpoint:* In clinical trials, an event or outcome that can be measured objectively to determine whether the intervention being studied is beneficial. The endpoints of a clinical trial are usually included in the study objectives. Some examples of endpoints are survival, improvements in quality of life, relief of symptoms, and disappearance of the tumor. (NCI)

:* Overall outcome that the protocol is designed to evaluate. Common endpoints are severe toxicity, disease progression, or death. (NLM)

* Enrolling:: The act of signing up participants into a study. Generally this process involves evaluating a participant with respect to the eligibility criteria of the study and going through the informed consent process. (NLM)

* Epidemiology:* The branch of medical science that deals with the study of incidence and distribution and control of a disease in a population. (NLM)

:* The study of the patterns, causes, and control of disease in groups of people. (NCI)

* Evaluable disease:: Disease that cannot be measured directly by the size of the tumor but can be evaluated by other methods specific to a particular clinical trial. (NCI)

* Evaluable patients:: Patients whose response to a treatment can be measured because enough information has been collected. (NCI)

* Expanded access:: Refers to any of the FDA procedures, such as compassionate use, parallel track, and treatment IND that distribute experimental drugs to participants who are failing on currently available treatments for their condition and also are unable to participate in ongoing clinical trials. (NLM)

* Expanded access trial:: A way to provide an investigational therapy to a patient who is not eligible to receive that therapy in a clinical trial, but who has a serious or life-threatening illness for which other treatments are not available. Expanded access allows a patient to receive promising but not yet fully studied or approved therapies when no other treatment option exists. Also called compassionate use trial. (NCI)

* Experimental:: In clinical trials, refers to a drug (including a new drug, dose, combination, or route of administration) or procedure that has undergone basic laboratory testing and received approval from the U.S. Food and Drug Administration (FDA) to be tested in human subjects. A drug or procedure may be approved by the FDA for use in one disease or condition, but be considered experimental in other diseases or conditions. Also called investigational. (NCI)

* Experimental drug:* A drug that is not FDA licensed for use in humans, or as a treatment for a particular condition (NLM)

:* A substance that has been tested in a laboratory and has gotten approval from the U.S. Food and Drug Administration (FDA) to be tested in people. A drug may be approved by the FDA for use in one disease or condition but be considered experimental or investigational in other diseases or conditions. Also called investigational drug. (NCI)

F

* Follow-up:: Monitoring a person's health over time after treatment. This includes keeping track of the health of people who participate in a clinical study or clinical trial for a period of time, both during the study and after the study ends. (NCI)

* Food and Drug Administration (FDA):: The U.S. Department of Health and Human Services agency responsible for ensuring the safety and effectiveness of all drugs, biologics, vaccines, and medical devices, including those used in the diagnosis, treatment, and prevention of HIV infection, AIDS, and AIDS-related opportunistic infections. The FDA also works with the blood banking industry to safeguard the nation's blood supply. Internet address: http://www.fda.gov/. (NLM)

H

* Healthy control:: In a clinical study, a person who does not have the disorder or disease being studied. Results from healthy controls are compared to results from the group being studied. (NCI)

* Historic cohort study:: A research study in which the medical records of groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) are compared for a particular outcome. Also called a retrospective cohort study. (NCI)

* Historical control subject:: An individual treated in the past and used in a comparison group when researchers analyze the results of a clinical study that had no control group. The use of a control, or comparison, group helps researchers determine the effects of a new treatment more accurately. (NCI)

* Hypothesis:: A supposition or assumption advanced as a basis for reasoning or argument, or as a guide to experimental investigation. (NLM)

I

* In vitro:: In the laboratory (outside the body). The opposite of in vivo (in the body). (NCI)

* In vivo:: In the body. The opposite of in vitro (outside the body or in the laboratory). (NCI)

* Incidence:: The number of new cases of a disease diagnosed each year. (NCI)

* Inclusion/exclusion criteria:: The medical or social standards determining whether a person may or may not be allowed to enter a clinical trial. These criteria are based on such factors as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions. It is important to note that inclusion and exclusion criteria are not used to reject people personally, but rather to identify appropriate participants and keep them safe. (NLM)

* Indication:: In medicine, a sign, symptom, or medical condition that leads to the recommendation of a treatment, test, or procedure. (NCI)

* Informed consent:* A process in which a person is given important facts about a medical procedure or treatment, a clinical trial, or genetic testing before deciding whether or not to participate. It also includes informing the patient when there is new information that may affect his or her decision to continue. Informed consent includes information about the possible risks, benefits, and limits of the procedure, treatment, trial, or genetic testing. (NCI)

:* The process of learning the key facts about a clinical trial before deciding whether or not to participate. It is also a continuing process throughout the study to provide information for participants. To help someone decide whether or not to participate, the doctors and nurses involved in the trial explain the details of the study. (NLM)

* Informed consent document:: A document that describes the rights of the study participants, and includes details about the study, such as its purpose, duration, required procedures, and key contacts. Risks and potential benefits are explained in the informed consent document. The participant then decides whether or not to sign the document. Informed consent is not a contract, and the participant may withdraw from the trial at any time. (NLM)

* Institutional Review Board (IRB):* 1. A committee of physicians, statisticians, researchers, community advocates, and others that ensures that a clinical trial is ethical and that the rights of study participants are protected. All clinical trials in the U.S. must be approved by an IRB before they begin. 2. Every institution that conducts or supports biomedical or behavioral research involving human participants must, by federal regulation, have an IRB that initially approves and periodically reviews the research in order to protect the rights of human participants. (NLM)

:* A group of scientists, doctors, clergy, and consumers that reviews and approves the action plan for every clinical trial. There is an Institutional Review Board at every health care facility that does clinical research. Institutional Review Boards are designed to protect the people who take part in a clinical trial. Institutional Review Boards check to see that the trial is well designed, legal, ethical, does not involve unneccesary risks, and includes safeguards for patients. Also called IRB. (NCI)

* Intent to treat:: Analysis of clinical trial results that includes all data from participants in the groups to which they were randomized even if they never received the treatment. (NLM)

* Intervention:: In medicine, a treatment or action taken to prevent or treat disease, or improve health in other ways. (NCI)

* Intervention group:: The group receiving the study agent that is being tested in a clinical trial or clinical study. (NCI)

* Intervention name:: The generic name of the precise intervention being studied. (NLM)

* Interventions:: Primary interventions being studied: types of interventions are Drug, Gene Transfer, Vaccine, Behavior, Device, or Procedure. (NLM)

* Investigational:: In clinical trials, refers to a drug (including a new drug, dose, combination, or route of administration) or procedure that has undergone basic laboratory testing and received approval from the U.S. Food and Drug Administration (FDA) to be tested in human subjects. A drug or procedure may be approved by the FDA for use in one disease or condition, but be considered investigational in other diseases or conditions. Also called experimental. (NCI)

* Investigational drug:: A substance that has been tested in a laboratory and has gotten approval from the U.S. Food and Drug Administration (FDA) to be tested in people. A drug may be approved by the FDA for use in one disease or condition but be considered investigational in other diseases or conditions. Also called experimental drug. (NCI)

* Investigational New Drug:: A new drug, antibiotic drug, or biological drug that is used in a clinical investigation. It also includes a biological product used in vitro for diagnostic purposes. (NLM)

* Investigator:: A researcher in a clinical trial or clinical study. (NCI)

L

* Levels of evidence:: A ranking system used to describe the strength of the results measured in a clinical trial or research study. The design of the study (such as a case report for an individual patient or a randomized double-blinded controlled clinical trial) and the endpoints measured (such as survival or quality of life) affect the strength of the evidence. (NCI)

M

* Masked:: The knowledge of intervention assignment. (NLM)

* Maximum tolerated dose:: The highest dose of a drug or treatment that does not cause unacceptable side effects. The maximum tolerated dose is determined in clinical trials by testing increasing doses on different groups of people until the highest dose with acceptable side effects is found. Also called MTD. (NCI)

* Medication:: A legal drug that is used to prevent, treat, or relieve symptoms of a disease or abnormal condition. (NCI)

* Medicine:: Refers to the practices and procedures used for the prevention, treatment, or relief of symptoms of a diseases or abnormal conditions. This term may also refer to a legal drug used for the same purpose. (NCI)

* Multicenter study:: A clinical trial that is carried out at more than one medical institution. (NCI)

* Multidisciplinary opinion:: A treatment planning approach in which a number of doctors who are experts in different specialties (disciplines) review and discuss the medical condition and treatment options of a patient. (NCI)

* Multiplicity:: A large number or variety. (NCI)

N

* National Institutes of Health:: NIH. A federal agency in the U.S. that conducts biomedical research in its own laboratories; supports the research of non-Federal scientists in universities, medical schools, hospitals, and research institutions throughout the country and abroad; helps in the training of research investigators; and fosters communication of medical information. Access the National Institutes of Health Web site at http://www.nih.gov. Also called NIH. (NCI)

* Natural history study:* A study that follows a group of people over time who have, or are at risk of developing, a specific medical condition or disease. A natural history study collects health information in order to understand how the medical condition or disease develops and how to treat it. (NCI)

:* Study of the natural development of something (such as an organism or a disease) over a period of time. (NLM)

* New Drug Application (NDA):: An application submitted by the manufacturer of a drug to the FDA - after clinical trials have been completed - for a license to market the drug for a specified indication. (NLM)

* Nonblinded:: Describes a clinical trial or other experiment in which the researchers know what treatments are being given to each study subject or experimental group. If human subjects are involved, they know what treatments they are receiving. (NCI)

* Nonconsecutive case series:: A clinical study that includes some, but not all, of the eligible patients identified by the researchers during the study registration period. This type of study does not usually have a control group. (NCI)

* Nonrandomized clinical trial:: A clinical trial in which the participants are not assigned by chance to different treatment groups. Participants may choose which group they want to be in, or they may be assigned to the groups by the researchers. (NCI)

O

* Objective improvement:: An improvement that can be measured by the health care provider (NCI)

* Objective response:: A measurable response. (NCI)

* Observation:: Closely monitoring a patient's condition but withholding treatment until symptoms appear or change. Also called watchful waiting, active surveillance, and expectant management. (NCI)

* Observational study:: A type of study in which individuals are observed or certain outcomes are measured. No attempt is made to affect the outcome (for example, no treatment is given). (NCI)

* Off-label:* Describes the legal use of a prescription drug to treat a disease or condition for which the drug has not been approved by the U.S. Food and Drug Administration. (NCI)

:* A drug prescribed for conditions other than those approved by the FDA. (NLM)

* Open label study:* A type of study in which both the health providers and the patients are aware of the drug or treatment being given. (NCI)

:* A clinical trial in which doctors and participants know which drug or vaccine is being administered. (NLM)

* Orphan drugs:: An FDA category that refers to medications used to treat diseases and conditions that occur rarely. There is little financial incentive for the pharmaceutical industry to develop medications for these diseases or conditions. Orphan drug status, however, gives a manufacturer specific financial incentives to develop and provide such medications. (NLM)

* Outcome:: A specific result or effect that can be measured. Examples of outcomes include decreased pain, reduced tumor size, and improvement of disease. (NCI)

* Outpatient:: A patient who visits a health care facility for diagnosis or treatment without spending the night. Sometimes called a day patient. (NCI)

* Over-the-counter:: A medicine that can be bought without a prescription (doctor's order). Examples include analgesics (pain relievers) such as aspirin and acetaminophen. Also called nonprescription and OTC. (NCI)

P

* Patient advocate:: A person who helps a patient work with others who have an effect on the patient's health, including doctors, insurance companies, employers, case managers, and lawyers. A patient advocate helps resolve issues about health care, medical bills, and job discrimination related to a patient's medical condition. (NCI)

* Peer review:: Review of a clinical trial by experts chosen by the study sponsor. These experts review the trials for scientific merit, participant safety, and ethical considerations. (NLM)

* Pharmacokinetics:: The processes (in a living organism) of absorption, distribution, metabolism, and excretion of a drug or vaccine. (NLM)

* Phase I trial:* The first step in testing a new treatment in humans. These studies test the best way to give a new treatment (for example, by mouth, intravenous infusion, or injection) and the best dose. The dose is usually increased a little at a time in order to find the highest dose that does not cause harmful side effects. Because little is known about the possible risks and benefits of the treatments being tested, phase I trials usually include only a small number of patients who have not been helped by other treatments. (NCI)

:* Initial studies to determine the metabolism and pharmacologic actions of drugs in humans, the side effects associated with increasing doses, and to gain early evidence of effectiveness; may include healthy participants and/or patients. (NLM)

* Phase I/II trial:: A trial to study the safety, dosage levels, and response to a new treatment. (NCI)

* Phase II trial:* A study to test whether a new treatment has an effect (NCI)

:* Controlled clinical studies conducted to evaluate the effectiveness of the drug for a particular indication or indications in patients with the disease or condition under study and to determine the common short-term side effects and risks. (NLM)

* Phase II/III trial:: A trial to study response to a new treatment and the effectiveness of the treatment compared with the standard treatment regimen. (NCI)

* Phase III trial:* A study to compare the results of people taking a new treatment with the results of people taking the standard treatment (for example, which group has better survival rates or fewer side effects). In most cases, studies move into phase III only after a treatment seems to work in phases I and II. Phase III trials may include hundreds of people. (NCI)

:* Expanded controlled and uncontrolled trials after preliminary evidence suggesting effectiveness of the drug has been obtained, and are intended to gather additional information to evaluate the overall benefit-risk relationship of the drug and provide and adequate basis for physician labeling. (NLM)

* Phase IV trial:* After a treatment has been approved and is being marketed, it is studied in a phase IV trial to evaluate side effects that were not apparent in the phase III trial. Thousands of people are involved in a phase IV trial. (NCI)

:* Post-marketing studies to delineate additional information including the drug's risks, benefits, and optimal use. (NLM)

* Pilot study:: The initial study examining a new method or treatment. (NCI)

* Placebo:* A placebo is an inactive pill, liquid, or powder that has no treatment value. In clinical trials, experimental treatments are often compared with placebos to assess the treatment's effectiveness. (NLM)

:* An inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or treatment are compared to the effects of the placebo. (NCI)

* Placebo controlled study:* A method of investigation of drugs in which an inactive substance (the placebo) is given to one group of participants, while the drug being tested is given to another group. The results obtained in the two groups are then compared to see if the investigational treatment is more effective in treating the condition. (NLM)

:* Refers to a clinical study in which the control patients receive a placebo. (NCI)

* Placebo effect:: A physical or emotional change, occurring after a substance is taken or administered, that is not the result of any special property of the substance. The change may be beneficial, reflecting the expectations of the participant and, often, the expectations of the person giving the substance. (NLM)

* Placebo therapy:: An inactive treatment or procedure that is intended to mimic as closely as possible a therapy in a clinical trial. Also called sham therapy. (NCI)

* Population study:: A study of a group of individuals taken from the general population who share a common characteristic, such as age, sex, or health condition. This group may be studied for different reasons, such as their response to a drug or risk of getting a disease. (NCI)

* Preclinical:* Refers to the testing of experimental drugs in the test tube or in animals - the testing that occurs before trials in humans may be carried out. (NLM)

:* Research using animals to find out if a drug, procedure, or treatment is likely to be useful. Preclinical studies take place before any testing in humans is done. (NCI)

* Predictive factor:: A situation or condition that may increase a person's risk of developing a certain disease or disorder. (NCI)

* Prevention:: In medicine, action taken to decrease the chance of getting a disease or condition. (NCI)

* Prevention trials:: Refers to trials to find better ways to prevent disease in people who have never had the disease or to prevent a disease from returning. These approaches may include medicines, vaccines, vitamins, minerals, or lifestyle changes. (NLM)

* Preventive:: Used to prevent disease. (NCI)

* Primary endpoint:: The main result that is measured at the end of a study to see if a given treatment worked (e.g., the number of deaths or the difference in survival between the treatment group and the control group). What the primary endpoint will be is decided before the study begins. (NCI)

* Prospective:: In medicine, a study or clinical trial in which participants are identified and then followed forward in time. (NCI)

* Prospective cohort study:: A research study that follows over time groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) and compares them for a particular outcome. (NCI)

* Protocol:* A study plan on which all clinical trials are based. The plan is carefully designed to safeguard the health of the participants as well as answer specific research questions. A protocol describes what types of people may participate in the trial; the schedule of tests, procedures, medications, and dosages; and the length of the study. While in a clinical trial, participants following a protocol are seen regularly by the research staff to monitor their health and to determine the safety and effectiveness of their treatment (NLM)

:* An action plan for a clinical trial. The plan states what the study will do, how, and why. It explains how many people will be in it, who is eligible to participate, what study agents or other interventions they will be given, what tests they will receive and how often, and what information will be gathered. (NCI)

Q

* Quality of life trials (or supportive care trials):: Refers to trials that explore ways to improve comfort and quality of life for individuals with a chronic illness. (NLM)

R

* Randomization:* A method based on chance by which study participants are assigned to a treatment group. Randomization minimizes the differences among groups by equally distributing people with particular characteristics among all the trial arms. The researchers do not know which treatment is better. From what is known at the time, any one of the treatments chosen could be of benefit to the participant (NLM)

:* When referring to an experiment or clinical trial, the process by which animal or human subjects are assigned by chance to separate groups that compare different treatments or other interventions. Randomization gives each participant an equal chance of being assigned to any of the groups. (NCI)

* Randomized clinical trial:* A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial. (NCI)

:* A study in which participants are randomly (i.e., by chance) assigned to one of two or more treatment arms of a clinical trial. Occasionally placebos are utilized. (NLM)

* Recruiting:: The period during which a trial is attempting to identify and enroll participants. Recruitment activites can include advertising and other ways of solicting interest from possible particpants (NLM)

* Recruitment status:: Indicates the current stage of a trial, whether it is planned, ongoing, or completed. (NLM)

* Regimen:: A treatment plan that specifies the dosage, the schedule, and the duration of treatment. (NCI)

* Retrospective:: Looking back at events that have already taken place. (NCI)

* Retrospective cohort study:: A research study in which the medical records of groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) are compared for a particular outcome. Also called a historic cohort study. (NCI)

* Retrospective study:: A study that compares two groups of people: those with the disease or condition under study (cases) and a very similar group of people who do not have the disease or condition (controls). Researchers study the medical and lifestyle histories of the people in each group to learn what factors may be associated with the disease or condition. For example, one group may have been exposed to a particular substance that the other was not. Also called a case-control study. (NCI)

* Risk-benefit ratio:: The risk to individual participants versus the potential benefits. The risk/benefit ratio may differ depending on the condition being treated. (NLM)

S

* Screening trials:: Refers to trials which test the best way to detect certain diseases or health conditions. (NLM)

* Selection bias:: An error in choosing the individuals or groups to take part in a study. Ideally, the subjects in a study should be very similar to one another and to the larger population from which they are drawn (for example, all individuals with the same disease or condition). If there are important differences, the results of the study may not be valid. (NCI)

* Sham therapy:: An inactive treatment or procedure that is intended to mimic as closely as possible a therapy in a clinical trial. Also called placebo therapy. (NCI)

* Side effect:* A problem that occurs when treatment affects healthy tissues or organs. (NCI)

:* Any undesired actions or effects of a drug or treatment. Negative or adverse effects may include headache, nausea, hair loss, skin irritation, or other physical problems. Experimental drugs must be evaluated for both immediate and long-term side effects (NLM)

* Significant:: In statistics, describes a mathematical measure of difference between groups. The difference is said to be significant if it is greater than what might be expected to happen by chance alone. Also called statistically significant. (NCI)

* Single blind study:* A type of clinical trial in which only the doctor knows whether a patient is taking the standard treatment or the new treatment being tested. This helps prevent bias in treatment studies. (NCI)

:* A study in which one party, either the investigator or participant, is unaware of what medication the participant is taking; also called single-masked study. (NLM)

* Standard treatment:: A treatment currently in wide use and approved by the FDA, considered to be effective in the treatment of a specific disease or condition. (NLM)

* Standards of care:: Treatment regimen or medical management based on state of the art participant care. (NLM)

* Statistical significance:: The probability that an event or difference occurred by chance alone. In clinical trials, the level of statistical significance depends on the number of participants studied and the observations made, as well as the magnitude of differences observed. (NLM)

* Study endpoint:: A primary or secondary outcome used to judge the effectiveness of a treatment. (NLM)

* Study type:: The primary investigative techniques used in an observational protocol; types are Purpose, Duration, Selection, and Timing. (NLM)

T

* Toxicity:: An adverse effect produced by a drug that is detrimental to the participant's health. The level of toxicity associated with a drug will vary depending on the condition which the drug is used to treat. (NLM)

* Treatment IND:: IND stands for Investigational New Drug application, which is part of the process to get approval from the FDA for marketing a new prescription drug in the U.S. It makes promising new drugs available to desperately ill participants as early in the drug development process as possible. Treatment INDs are made available to participants before general marketing begins, typically during Phase III studies. To be considered for a treatment IND a participant cannot be eligible to be in the definitive clinical trial. (NLM)

* Treatment trials:: Refers to trials which test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy. (NLM)

* t-test:: A statistical test that is used to find out if there is a real difference between the means (averages) of two different groups. It is sometimes used to see if there is a significant difference in response to treatment between groups in a clinical trial. (NCI)

U

* Uncontrolled study:: A clinical study that lacks a comparison (i.e., a control) group. (NCI)

References

* NCI: cite web | url = http://www.cancer.gov/dictionary/db_alpha.aspx | publisher = National Cancer Institute | title = Dictionary of Cancer Terms
* NLM: cite web | url = http://clinicaltrials.gov/ct2/info/glossary | publisher = U.S. National Library of Medicine | title = Glossary of Clinical Trials Terms