Glossary of clinical trial terms

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Terms listed alphabetically

Adverse event

Unfavorable change in a person’s health 

Arm

Group of participants in a clinical trial

Baseline

Time point when an eligible clinical trial participant’s health status is first measured 

ClinicalTrials.Gov 

U.S. government website that lists clinical trials 

Concomitant medication

Medication taken in addition to the intervention/treatment given in a clinical trial

Control group

Clinical trial participants receiving a standard treatment or placebo rather than the potential treatment being studied

Controlled clinical trial

Clinical trial that includes a control group

Data monitoring committee (DMC)

Independent group that monitors the safety and scientific integrity of a clinical trial

Double-blind trial

Clinical trial where participants and the trial team don’t know which intervention/treatment is randomly assigned to each participant

Efficacy

Ability of a potential treatment to produce a desired effect

Eligibility criteria

Requirements that clinical trial participants must meet (inclusion criteria) or not meet (exclusion criteria)

Exclusion criteria 

Eligibility criteria that state the characteristics a clinical trial participant must not have 

Good Clinical Practice (GCP)

Set of guidelines for designing and running a clinical trial to make sure results are helpful and participants are protected

Healthy volunteer

Person in a clinical trial who does not have known health problems 

Inclusion criteria

Eligibility criteria that state the characteristics a clinical trial participant must have

Process followed by a clinical trial team to make sure potential participants know what will happen if they join a trial 

Document that provides details about a clinical trial, such as its purpose, length, procedures, risks, and potential benefits

Inpatient

Person who receives treatment and stays in a medical facility overnight

Institutional review board (IRB)/independent ethics committee (IEC)

Independent group that ensures the rights, safety, and well-being of clinical trial participants are protected

Intervention/treatment

Drug, medical device, procedure, vaccine, or change in behavior tested in a clinical trial 

Investigational drug

Drug being studied to see if a person’s health improves while taking it 

Investigator

Researcher or healthcare provider who works on a clinical trial 

Office for Human Research Protection (OHRP)

U.S. government agency whose role is to protect people in government-funded clinical trials

Open-label trial

Clinical trial where the trial team and participants know which intervention/treatment is given

Outpatient

Person who receives treatment but does not stay in a medical facility overnight

Patient volunteer 

Person in a clinical trial who has a known health problem

Pharmacokinetics 

Study of how the body processes a drug

Phase

Stage of a clinical trial

Placebo

Treatment or procedure that does not have any true physical effects

Pre-clinical data

Data from tests done in a laboratory before testing can be done in people 

Principal investigator

Researcher or healthcare provider who leads a clinical trial 

Protocol

Written plan that describes all parts of a clinical trial

Randomization

Process of assigning participants to clinical trial groups by chance

Screening

Process that determines if a person is eligible to participate in a clinical trial

Company, organization, or person that initiates and controls a clinical trial

Standard treatment

Most commonly used and best available treatment for a disease or health condition

Stopping rules

Safety criteria that would either pause or stop a clinical trial

Study coordinator

Person who handles day-to-day responsibilities of a clinical trial for a trial site

Study design 

Plan for conducting a clinical trial

Sources

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