Glossary of Clinical Trial Terms
This glossary provides clear and concise definitions of essential clinical trial terms. It is designed to support researchers, sponsors, patients, and healthcare professionals in understanding the language and regulatory landscape of clinical research.
A - B - C - D - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z
A
What is an Adverse Event: A negative change or medical occurrence that happens during a clinical trial or within a certain time period after the trial has ended. An adverse event may or may not be caused by the treatment being studied.
What is an Amendment: A formal change or addition made to the protocol of a clinical study.
What is an Assent: Agreement from a participant, often a minor, who is not legally able to give full consent but can understand the study and agree to participate.
What is an Arm assignment: The assignment of a group or subgroup of participants in a clinical trial to receive interventions, or no interventions, as specified in the study protocol.
What is an Assessment: A procedure (e.g. a blood test, scan, etc.) used to generate data required by the trial.
B
What is Background therapy: Background therapy is the current medication that is routinely taken as a standard of care for a particular condition/disease.
What is a Baseline: Initial set of measurements taken at the start of a study before the participant receives any treatment, used for comparison throughout the study.
What is a Basket Trial: A research study that tests one study treatment for different diseases and conditions.
What is Bias: A systematic error or deviation from the truth, in results or inferences, in clinical research.
What is a Biomarker: Something in the body that is measured as an indicator of personal health or disease.
What is Blinding (Masking): A method used to prevent study participants, healthcare providers, and/or researchers from knowing which intervention the participant is receiving to eliminate bias.
What is 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.
C
What is a Case Report Form (CRF): A document used to record data on each participant during a clinical trial.
What is a Clinical Endpoint: A primary outcome used to judge the effectiveness of a treatment.
What is a Clinical Trial: A research study conducted with human volunteers to evaluate the safety and efficacy of a medical treatment or intervention.
What is a Clinical study: A research study conducted in human volunteers to answer specific health questions. Interventional studies determine whether experimental treatments or new ways of using known therapies are safe and effective under controlled environments.
What is a Cohort: A group of individuals sharing a common characteristic, such as age or treatment, who are followed over a period of time.
What is a Control: The control or “standard” treatment is compared against the investigational treatment. It is there to show that an approved treatment in the trial works, and the investigational treatment is compared against it.
What is a Cross-over trial: A clinical trial where groups of volunteers are administered two or more interventions in a specific order. For example, a “two-by-two” cross-over trial design is where one group receives drug A at the beginning of the trial and then receives drug B for the rest of the trial. In the second group, participants receive drug B first and then drug A. Thus, the term “cross-over” is used to describe the order in which they are assigned; for example drug A and then drug B, or drug B and then drug A. All participants receive both drugs during the study.
D
What is Data Monitoring Committee (DMC): An independent group of experts who monitor patient safety and treatment efficacy data while a clinical trial is ongoing.
What is a Data and Safety Monitoring Plan (DSMP): The DSMP deals with how the framework for safety and data monitoring of the clinical trials is laid out, and other factors such as how adverse events will be reported to the IRB and the NIH and, how the NIH Guidelines and FDA regulations for INDs and IDEs will be applied.
What is Dose-response Relationship: The relationship between the dose of a drug and the magnitude of its therapeutic or adverse effects.
What is Dosing discontinuation: Point/time when a patient volunteer permanently stops taking study drug for any reason. This may be at the end of the study or before the end if the patient wants to stop taking the medicine for some reason.
What is a Double-blind: In a double-blind trial, only the study pharmacist knows what study medication a participant is receiving; the participants, doctors, nurses, and other clinical trial staff are not informed.
E
What is a Early patient withdrawal (premature withdrawal): Point/time when a patient exits from a trial prior to the planned completion of all investigational/trial drug administration and all assessments (including follow-up).
What is Early Phase: Termed as Phase 0 previously, it defines the exploratory trials conducted before traditional phase 1 trials, which aims to explore/investigate how/whether a drug affects the body.
What is Efficacy: The ability of a drug or treatment to produce the desired beneficial effect in controlled clinical trials.
What is an Endpoint: A primary or secondary outcome used to assess the effectiveness of a treatment in a clinical trial.
What is Eligibility Criteria: These are the key requirements that individuals must meet to participate in a clinical study. Eligibility criteria include both inclusion criteria (which define who can join the study) and exclusion criteria (which specify who cannot participate). These criteria can be based on various factors such as health status, age, sex, or specific medical conditions.
What is Epoch: The planned stages of volunteer participation in a trial typically include assessing eligibility, a wash-out period to discontinue any previous treatments, administering the trial treatment, and conducting follow-up after the treatment has concluded.
What is an Ethics Committee: A group that reviews and monitors biomedical research involving humans, ensuring that the study is ethical, and the rights and welfare of participants are protected.
What is Enrollment: This refers to the number of participants in a clinical study. The “estimated” enrollment is the target number of participants that researchers aim to recruit for the study.
What is an Exclusion Criteria: These are specific factors that disqualify a person from participating in a clinical study. Exclusion criteria are a subset of eligibility criteria, ensuring that only suitable participants are included in the research.
What is an Emergency Use Authorization (EUA): It is the process that makes a vaccine or a treatment available during a public health emergency, for example, COVID-19 vaccines. Under EUA, the vaccine/treatment is made public before all the research is complete, and even before the full approval for its release.
What is the European Medicines Agency (EMA): European Medicines Agency. An agency of the European Union that oversees the use of medicinal products.
What is the FDA (Food and Drug Administration): The U.S. federal agency responsible for regulating food, drugs, medical devices, cosmetics, and more.
F
What is a Feasibility Study: A small-scale study conducted to determine whether a larger study is practical and what modifications may be needed.
What is a Formulation: The composition of a drug, including its active and inactive ingredients.
G
What is Good Clinical Practice (GCP): An international standard for the design, conduct, performance, monitoring, auditing, recording, analysis, and reporting of clinical trials.
What is Gender-based Eligibility: A type of eligibility criteria that determines participation in a clinical study based on an individual’s self-identified gender. Gender identity refers to a person’s personal sense of gender, which may or may not align with their biological sex.
What is Genotype: The genetic makeup of an individual, often studied to understand the impact on drug response.
What is Guideline: A document providing principles or recommendations on how to carry out certain tasks or processes in clinical research.
H
What is the Health Authority: A national or international health agency that has authority over and regulates a clinical study.
What is an Hypothesis: A proposed explanation made based on limited evidence as a starting point for further investigation in a study.
What is an Hazard Ratio: A measure used in survival analysis to compare the risk of an event happening in one group versus another.
What is an Human Subject: An individual who participates in research, either as a recipient of the test article or as a control.
What is a theHealth Insurance Portability and Accountability Act (HIPAA) Privacy Rule: It is the first comprehensive Federal regulation safeguarding the privacy of personal health information. This rule governs how specific healthcare groups, organizations, or businesses, referred to as covered entities, manage individually identifiable health information, known as protected health information.
I
What is an Indication: A disease, symptom, or particular set of circumstances that make a particular test, medication, procedure, or surgery advisable. For a treatment, an indication refers to the use of that treatment in treating a particular disease
What is an Institutional Review Board (IRB) / Independent Ethics Committee (IEC): An IRB or IEC is a group made up of medical experts, scientists, and non-scientists. Their job is to protect the rights and safety of people participating in clinical trials. They do this by reviewing and approving trial plans and changes and ensuring that the methods used to get and document participants’ consent are appropriate.
What is an Intervention: An intervention is any procedure or treatment used in clinical research. This could include drugs, supplements, vaccines, behaviour changes, or device modifications.
What is an Investigational New Drug Application (IND): An IND is a request to the FDA for permission to test a new drug or biological product on humans. This approval is needed before shipping and administering any new drug or product that hasn’t been officially approved yet.
What is an Inclusion Criteria: The characteristics that must be present for an individual to be eligible to participate in a clinical trial.
What is an Informed Consent: The process by which a participant voluntarily confirms their willingness to participate in a study after being informed of all aspects that are relevant to their decision to participate.
What is an Interim Analysis: An analysis of data conducted before the data collection has been completed to assess the safety, efficacy, or other important measures.
What is an Interventional Study: Also called a clinical trial, this type of study involves participants receiving specific interventions as outlined in the study protocol. Researchers use these interventions to assess their effects on a health condition.
What is an Investigational Drug: This refers to a drug being tested in a trial. It is also known as an “investigational new drug” or “investigational medicinal product.”
J
What is Joint Monitoring: A collaborative effort between different stakeholders to monitor the conduct of a clinical trial, ensuring compliance with protocols and regulations.
What is a Justification: The reasoning behind certain decisions made during the design or conduct of a clinical trial.
What is a Journal Publication: The process of publishing the findings of a clinical trial in a scientific journal.
K
What is a Kaplan-Meier Estimate: A statistical method used to estimate the survival function from lifetime data.
What is a Key Opinion Leader (KOL): An expert in a particular field whose opinion influences the decisions of others, often involved in clinical research design and analysis.
What is Knowledge Transfer: The process of sharing or disseminating knowledge, skills, or technology from one organization or individual to another, especially in clinical research contexts.
L
What is a Legally Authorized Representative (LAR): A person authorized under applicable law to consent on behalf of a prospective participant to their participation in a clinical trial.
What is a Longitudinal Study: A study that follows participants over a long period of time to observe changes and long-term outcomes.
What is Lost to Follow-Up: A term used when a participant in a clinical study cannot be contacted or does not return for follow-up assessments.
M
What is a Manual of Procedures (MOP): An MOP is a set of procedures describing study conduct and is developed to facilitate consistency in protocol implementation and data collection across study participants and clinical sites.
What is a Medication number: A unique number on the label of each investigational drug package that is used in a trial to dispense and track medication. The number is used to make sure the drug is supplied in the right quantities to different research centers.
What is a Meta-Analysis: A statistical method that combines the results of multiple studies to arrive at a conclusion about the body of research.
What is Monitoring: The ongoing oversight of a clinical trial, often involving data review, site visits, and ensuring adherence to the study protocol.
What is a Multi-Center Trial: A clinical trial conducted at several different locations (hospitals, clinics, etc.) to increase the generalizability of the findings.
N
What is a Non-Inferiority Trial: A type of clinical trial conducted to show that a new treatment is not worse than an existing treatment by more than a small, predefined amount.
What is an NDA (New Drug Application): The application submitted to the FDA for approval to market a new drug in the United States.
What is aNull Hypothesis: A hypothesis that there is no effect or no difference, often the starting point in statistical testing.
What is a NCT Number: This is a unique code assigned to each clinical study listed on ClinicalTrials.gov. It starts with “NCT” followed by an 8-digit number, such as NCT00000419.
What is a No Intervention Arm: This is a type of study group where participants do not receive any treatment or intervention during the clinical trial.
O
What is an Open-Label Study: A type of study where both the researchers and participants know which treatment is being administered, with no blinding involved.
What is an Observational Study: A study in which participants are observed or certain outcomes are measured without treatment being applied by the researchers.
What is an Other Adverse Event: An adverse event that does not meet the criteria for a serious adverse event. It does not result in death, is not life-threatening, does not require hospitalization or extend an existing hospital stay, does not lead to significant disability or disrupt normal life functions, and does not cause a birth defect or congenital anomaly. It also does not put the participant in immediate danger or require medical or surgical intervention to prevent serious outcomes.
What is an Other Study IDs: These are identifiers or ID numbers, other than the NCT number, assigned to a clinical study by the sponsor, funders, or other entities. These may include unique identifiers from other trial registries or National Institutes of Health grant numbers.
What is Other Terms: In the search feature, the “Other terms” field is used to refine a search. For example, entering the name of a drug or the NCT number of a clinical study can help narrow the search to records containing those specific terms.
What is an Outcome measure: In clinical trials, a set measurement that is described in the protocol and is used to evaluate the effect of an intervention on participants.
P
What is Part: A subdivision of a single protocol into major building blocks. These parts often are independent of each other and have different objectives or different groups of volunteers. For example, a single-dose design and a multiple-dose design may be combined into one protocol (a protocol with two parts) or the same study design could be used with different groups of patients with different severity of a disease.
What is a Patient Registry: A type of observational study that gathers detailed information about patients’ medical conditions and treatments. This data helps researchers understand how conditions or treatments impact patients in real-world settings.
What is a Placebo: An inactive substance designed to resemble the drug being tested, used in clinical trials to test the efficacy of the active drug.
What is a Protocol: A document that describes the objectives, design, methodology, statistical considerations, and organization of a clinical trial.
What is a Principal Investigator (PI): The person responsible for the conduct of the clinical trial at a trial site, overseeing all aspects of the study.
What is a Phase: Categories defined by the Food and Drug Administration (FDA) to describe the stages of a drug’s clinical trial. These categories are based on specific characteristics, such as the study’s objective and the number of participants involved. The four phases are Phase 1, Phase 2, Phase 3, and Phase 4.
Q
What is a Quality Assurance (QA): Systematic activities implemented to ensure that the clinical trial is being conducted in accordance with regulatory requirements and good clinical practice (GCP).
What is a Query: A request for clarification on specific data points in a clinical trial, often raised during data monitoring or review.
What is Quarantine: The isolation of participants or materials suspected of being exposed to or contaminated with infectious agent
R
What is Randomization: The process of assigning trial participants to different treatment groups using random methods, ensuring that each participant has an equal chance of receiving any given treatment.
What is Randomized allocation: A strategy in which participants are randomly assigned to study arms of a clinical trial by computer.
What is a Randomization number: A unique number assigned to each randomized patient that is used to identify individuals but maintain anonymity, corresponding to a specific study arm assignment.
What is a Regulatory Authority: Government agencies responsible for overseeing and regulating clinical research, such as the FDA in the United States.
R
What is a Risk-Benefit Ratio: The comparison of the risk of harm to the potential benefits of a treatment or intervention in a clinical trial.
What is a Recruitment Plan: A strategy that details how participants will be selected for the study and the steps that will be taken to achieve the recruitment target.
What is a Retention Plan: A strategy that outlines the approaches and methods to be used to ensure participants remain engaged and continue their involvement throughout the clinical trial.
What is a Run-in period: The elapsed time before a trial starts when no investigational drug is given to trial participants. During this time patients may still receive standard treatments for their disease if these treatments are allowed within the trial period.
S
What is a Screening: The process of evaluating potential participants to determine if they meet the eligibility criteria for a clinical trial.
What is a Serious Adverse Event (SAE): Any undesirable experience that results in death, is life-threatening, requires hospitalization, or causes significant disability/incapacity.
What is a Site Monitoring Visit: A visit conducted by a monitor to ensure that the study is being conducted properly at the clinical site, adhering to the protocol and regulatory requirements.
What is a Sham Comparator Arm: A study group where participants receive a procedure or device that mimics the actual treatment being tested but lacks any active components or processes.
What is a Statistical Analysis Plan (SAP): A detailed document outlining the statistical methods and considerations for analyzing the data gathered during a clinical study.
What is a Standard Operating Procedures (SOPs): Comprehensive written guidelines designed to ensure consistent execution of specific tasks across various studies and patients at a particular site.
What is Stopping Rules: Predetermined safety guidelines that can temporarily suspend or permanently stop a study due to reasons such as futility or potential risks to participants.
What is a Stratification: The process of dividing a study population into distinct subgroups based on characteristics like age or gender to account for factors that could influence the study’s outcomes.
What is a Sponsor: The Sponsor is the organization or person who oversees multiple sites conducting the clinical trial.
What is a Study completed date: The date on which the last trial participant made the final visit to the study location (that is, "last subject, last visit") and the last samples were collected or last tests performed.
What is a Subject: An individual (either a healthy volunteer or a patient volunteer) whose reactions or responses to certain interventions are evaluated during a clinical trial. May also be referred to as a trial participant.
What is a Subject number: A unique number assigned to each participant who enrols into a clinical trial.
T
What is a Treatment Arm: A group or subgroup of participants in a clinical trial that receives a specific treatment or intervention.
What is Translational Research: A type of research that aims to translate findings from basic science into practical applications that enhance human health and well-being.
What is a Trial Master File (TMF): A collection of essential documents that allow the conduct of a clinical trial to be understood and evaluated.
U
What is Unblinding: Revealing the treatment assignment to participants, investigators, or both in a clinical trial, usually after the study is completed or at a predetermined time point.
What is an Underpowered Study: A study with insufficient sample size to detect a statistically significant effect.
What is an Unanticipated Adverse Device Effects (UADEs): These refer to any unexpected serious adverse effect on health or safety, any life-threatening issue, or any death linked to a medical device.
What is a Urgent Safety Measure (USM): A measure taken to protect the participants in a clinical trial from an immediate hazard to their health or safety.
V
What is a Variable: Information collected during a clinical trial either from direct or indirect data. For example, one variable might be “weight,” which would then be checked at specified time points throughout the trial.
What is a Vulnerable Population: Groups of individuals who may be at increased risk of coercion or undue influence in research settings, such as children, prisoners, or individuals with cognitive impairments.
What is a Voluntary Consent: Consent given freely and without coercion or undue influence, ensuring that participants are participating in a clinical trial of their own free will.
What is a Vaccine: A biological preparation that provides active acquired immunity to a particular infectious disease.
W
What is a Wash-out period: The period of time allowed for all of the administered drug to be eliminated from the body.
What is a Withdrawal: The removal of a participant from a clinical trial, either by the participant’s choice or by the investigator, often due to safety concerns or non-compliance.
This glossary will be updated regularly to reflect changes in clinical trial regulations, practices, and terminology.