Czech Clinical Research Institute

About Clinical Studies

What is a Clinical Study?

A clinical study involves research using human volunteers (also called participants) that is intended to add to medical knowledge. There are two main types of clinical studies: clinical trials and observational studies.

Clinical Trials

In a clinical trial (also called an interventional study), participants receive specific interventions according to the research plan or protocol created by the investigators. These interventions may be medical products, such as drugs or devices; procedures; or changes to participants' behavior, for example, diet. Clinical trials may compare a new medical approach to a standard one that is already available or to a placebo that contains no active ingredients or to no intervention. Some clinical trials compare interventions that are already available to each other. When a new product or approach is being studied, it is not usually known whether it will be helpful, harmful, or no different than available alternatives (including no intervention). The investigators try to determine the safety and efficacy of the intervention by measuring certain outcomes in the participants. For example, investigators may give a drug or treatment to participants who have high blood pressure to see whether their blood pressure decreases. Clinical trials used in drug development are sometimes described by phase. These phases are defined by the Food and Drug Administration (FDA).

Observational Studies

In an observational study, investigators assess health outcomes in groups of participants according to a protocol or research plan. Participants may receive interventions, which can include medical products, such as drugs or devices, or procedures as part of their routine medical care, but participants are not assigned to specific interventions by the investigator (as in a clinical trial). For example, investigators may observe a group of older adults to learn more about the effects of different lifestyles on cardiac health.

Who Conducts Clinical Studies?

Every clinical study is led by a principal investigator, who is often a medical doctor. Clinical studies also have a research team that may include doctors, nurses, social workers, and other health care professionals. Clinical studies can be sponsored, or funded, by pharmaceutical companies, academic medical centers, voluntary groups, and other organizations. Physicians, health care providers, and other individuals can also sponsor clinical research.

Where Are Clinical Studies Conducted?

Clinical studies can take place in many locations, including hospitals, universities, doctors' offices, and community clinics. The location depends on who is conducting the study.

How Long Do Clinical Studies Last?

The length of a clinical study varies, depending on what is being studied. Participants are told how long the study will last before enrolling.

Reasons for Conducting Clinical Studies

In general, clinical studies are designed to add to medical knowledge related to the treatment, diagnosis, and prevention of diseases or conditions. Some common reasons for conducting clinical studies include:

Evaluating one or more interventions (for example, drugs, medical devices, approaches to surgery or radiation therapy) for treating a disease, syndrome, or condition.
Finding ways to prevent the initial development or recurrence of a disease or condition. These can include medicines, vaccines, or lifestyle changes, among other approaches.
Evaluating one or more interventions aimed at identifying or diagnosing a particular disease or condition.
Examining methods for identifying a condition or risk factors for that condition.
Exploring and measuring ways to improve the comfort and quality of life of people with a chronic illness through supportive care.

Participating in Clinical Studies

A clinical study is conducted according to a research plan known as the protocol. The protocol is designed to answer specific research questions as well as safeguard the health of participants. It contains the following information:

The reason for conducting the study
Who may participate in the study (the eligibility criteria)
The number of participants needed
The schedule of tests, procedures, or drugs and their dosages
The length of the study
What information will be gathered about the participants

Who Can Participate in a Clinical Study?

Clinical studies have standards outlining who can participate, called eligibility criteria, which are listed in the protocol. Some research studies seek participants who have the illnesses or conditions that will be studied. Other studies are looking for healthy participants. And some studies are limited to a predetermined group of people who are asked by researchers to enroll.

Eligibility

The factors that allow someone to participate in a clinical study are called inclusion criteria, and the factors that disqualify someone from participating are called exclusion criteria. These are based on things such as age, gender, the type and stage of a disease, previous treatment history, and other medical conditions.

How Are Participants Protected?

Informed consent is a process in which researchers provide potential and enrolled participants with information about a clinical study. This information helps people decide whether they want to enroll, or continue to participate, in the study. The informed consent process is intended to protect participants and should provide enough information for a person to understand the risks of, potential benefits of, and alternatives to the study. In addition to the informed consent document, the process may involve recruitment materials, verbal instructions, question-and-answer sessions, and activities to measure participant understanding. In general, a person must sign an informed consent document before entering a study to show that he or she was given information on risks, potential benefits, and alternatives and understands it. Signing the document and providing consent is not a contract. Participants may withdraw from a study at any time, even if the study is not over.

Relationship to Usual Health Care

Typically participants continue to see their usual health care providers while enrolled in a clinical study. While most clinical studies provide participants with medical products or interventions related to the illness or condition being studied, they do not provide extended or complete health care. By having the participant's usual health care provider work with the research team, the participant can make sure that the study protocol will not conflict with other medications or treatments being received.

Considerations for Participation

Participating in a clinical study contributes to medical knowledge. The results of these studies can make a difference in the care of future patients by providing information about the benefits and risks of therapeutic, preventative, or diagnostic products or interventions. Clinical trials provide the basis for the development and marketing of new drugs, biological products, and medical devices. Sometimes, the safety and the effectiveness of the experimental approach or use may not be fully known at the time of the trial. Some trials may provide participants with the prospect of receiving direct medical benefits, while others do not. Most trials involve some risk of harm or injury to the participant, although it may not be more than the risks related to routine medical care or disease progression. Many trials require participants to undergo additional procedures, tests, and assessments based on the study protocol. These will be described in the informed consent document for a particular trial. A potential participant should also discuss these issues with members of the research team and with his or her usual health care provider.

Questions to Ask

Anyone interested in participating in a clinical study should know as much as possible about the study and feel comfortable asking the research team questions about the study, the related procedures, and any expenses. The following questions might be helpful during such a discussion. Answers to some of these questions are provided in the informed consent document. Many of these questions are specific to clinical trials, but some also apply to observational studies.

What is being studied?
Why do researchers believe the intervention being tested might be effective? Why might it not be effective? Has it been tested before?
What are the possible interventions that I might receive during the trial?
How will it be determined which interventions I receive (for example, by chance)?
Who will know which intervention I receive during the trial? Will I know? Will members of the research team know?
How do the possible risks, side effects, and benefits of this trial compare with those of my current treatment?
What will I have to do?
What tests and procedures are involved?
How often will I have to visit the hospital or clinic?
Will hospitalization be required?
How long will the study last?
Who will pay for my participation?
Will I be reimbursed for other expenses?
What type of long-term follow-up care is part of this trial?
If I benefit from the intervention, will I be allowed to continue receiving it after the trial ends?
Will results of the study be provided to me?
Who will oversee my medical care while I am in the trial?
What are my options if I am injured during the study?

Glossary

Accepts healthy volunteers

Indicates whether a clinical study allows people who do not have the condition or related conditions or symptoms being studied to participate in that study.

ACTIVE COMPARATOR ARM

A group of participants that receives an intervention that is considered to be effective. One of several Arm Types.

ACTIVE, NOT RECRUITING

The clinical study is ongoing (that is, participants are receiving an intervention or being examined), but potential participants are not currently being recruited or enrolled. A type of Recruitment Status.

ADVERSE EVENT

An unfavorable change in the health of a participant, including abnormal laboratory findings, that happens during a clinical study or within a certain time period after the study is over. This may or may not be caused by the intervention being studied.

ALLOCATION

A clinical trial design strategy used to assign participants to an arm of a study. Types of Allocation include Randomized, and Nonrandomized.

ARM

A group or subgroup of participants in a clinical trial who receives specific interventions, or no intervention, according to the study protocol. This is decided before the trial begins.

ARM TYPE

A general description of the clinical study arm. It identifies the role of the intervention that participants will receive. Types of arms include Experimental, Active comparator, Placebo comparator, Sham comparator, and No intervention.

BASELINE CHARACTERISTICS

Data collected at the beginning of a clinical study for all participants and for each arm or comparison group. These data include demographics, such as age and gender, and study-specific measures (for example, systolic blood pressure, prior antidepressant treatment).

BLINDING

A clinical trial design strategy in which one or more parties involved with the trial, such as the investigator or participant, do not know which participants have been assigned which interventions. Types of masking include none Open label, Single blind masking, and Double blind masking.

CLINICAL STUDY

A research study using human subjects to evaluate the effect of interventions or exposures on biomedical or health-related outcomes. Two types of clinical studies are interventional studies (or clinical trials) and observational studies.

CLINICAL TRIAL (or Interventional Study)

A clinical study in which participants are assigned to receive one or more interventions (or no intervention) so that researchers can evaluate the effects of the interventions on biomedical or health-related outcomes. The assignments are determined by the study protocol. Participants may receive diagnostic, therapeutic, or other types of interventions. A Study Type.

CLOSED STUDIES

Clinical studies that are no longer recruiting participants because they have enough participants already, because they are completed, or because they have been stopped for some reason. This also describes studies with very specific eligibility criteria that recruit participants by invitation only. Recruitment statuses for closed studies are:

Active, not recruiting
Completed
Terminated
Suspended
Withdrawn
Enrolling by invitation
Temporarily not available for expanded access
No longer available for expanded access
Approved for marketing

COLLABORATOR

A collaborator is an organization other than the sponsor that provides support for a clinical study. This may include funding, design, implementation, data analysis, or reporting.

COMPLETED

The clinical study has ended normally, and participants are no longer being examined or treated (that is, the "last subject, last visit" has occurred). A type of Recruitment Status.

CONDITION

A disease, disorder, syndrome, illness, or injury that is being studied. Conditions may also include other health-related issues such as lifespan, quality of life, and health risks.

CONTROLLED TRIAL

A type of clinical trial in which observations made during the trial are compared to a standard (called the control). The control may be observations from a group of participants in the same trial or observations from outside the trial (for example, from an earlier trial, called a "historical control").

CROSSOVER DESIGN

Describes a clinical trial in which groups of participants receive two or more interventions in a particular order. For example, a two-by-two crossover design involves two groups of participants. One group receives drug A during the initial phase of the trial, followed by drug B during a later phase. The other group receives drug B during the initial phase, followed by drug A during a later phase. So during the study, participants "cross over" to the other drug. All participants receive drug A and drug B at some point during the study, but in a different order, depending on the group to which they are assigned. One type of Intervention Model (Design).

DATA MONITORING COMMITTEE (DMC)

A group of independent scientists who monitor the safety and scientific integrity of a clinical trial. The group can recommend to the study sponsor that the study be stopped if it is not effective, if it is causing harm to participants, or if it is not likely to serve its scientific purpose. Committee members are chosen based on the scientific skills and knowledge needed to monitor the particular study. Also referred to as a data safety and monitoring board (DSMB).

DOUBLE BLIND MASKING

A type of masking in which two or more parties involved with the clinical trial do not know which participants have been assigned which interventions. Typically, this includes the investigator and participant.

ELIGIBILITY CRITERIA

The key standards that people who want to participate in a clinical study must meet or the characteristics that they must have. These include inclusion criteria and exclusion criteria. For example, a study might only accept participants who are above or below certain ages.

ENROLLING BY INVITATION

A clinical study that selects its participants from a population, or group of people, decided on in advance by the researchers. These studies are not open to everyone who meets the eligibility criteria, but only to people in that particular population, who are specifically invited to participate. A type of Recruitment Status.

ENROLLMENT

The number of participants in a clinical study. The "estimated enrollment" is the number of participants that the researchers need for the study.

EXCLUSION CRITERIA

The factors (or reasons) that prevent a person from participating in a clinical study.

EXPERIMENTAL ARM

A group of participants that receives the intervention that is the focus of the study. One of several Arm Types.

FOOD AND DRUG ADMINISTRATION (FDA)

An agency within the U.S. Department of Health and Human Services. FDA is responsible for protecting the public health by making sure that human and veterinary drugs, vaccines and other biological products, medical devices, the nation's food supply, cosmetics, dietary supplements, and products that give off radiation are safe, effective, and secure.

GENDERS ELIGIBLE FOR STUDY

The physical gender of persons who may participate in the clinical study (female, male, or both).

HEALTH AUTHORITY

A national or international health organization that has authority over the clinical study.

HUMAN SUBJECTS REVIEW BOARD

A group of people who review, approve, and monitor the clinical study protocol. Their role is to protect the rights and welfare of human research subjects participating in a study. The group typically includes people with varying backgrounds, including a community member, to make sure that research activities conducted by an organization are completely and adequately reviewed. Also known as an institutional review board (IRB) or ethics committee.

INCLUSION CRITERIA

The factors (or reasons) that allow a person to participate in a clinical study.

INFORMED CONSENT

A process in which researchers communicate with potential and enrolled participants about a clinical study. This is when researchers:

provide all the important information about the study, so that potential participants can decide whether to enroll (or if enrolled, to continue participating); ensure that potential participants understand the risks and potential benefits of participating in the study, and the alternatives to the research being conducted; and stress that enrolling in (and staying in) a clinical study is completely voluntary. Because giving consent to participate in research is not a contract, participants can leave a study at any time.

The goal of the informed consent process is to protect participants. It begins when a potential participant first asks for information about a study and continues throughout the study until the study ends. The researcher and potential participant have discussions that include answering the participant's questions about the research. All the important information about the study must also be given to the potential participant in a written document that is clear and easy to understand. This informed consent document is reviewed and approved by the human subjects review board for a study before it is given to potential participants. Generally, a person must sign an informed consent document to enroll in a study.

INTERVENTION

A process or action that is the focus of a clinical study. This can include giving participants drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches such as surveys, education, and interviews.

INTERVENTION MODEL (Design)

The general design describing the strategy in which interventions will be assigned to participants in a clinical study. Types of intervention models include Single group design, Parallel design, Crossover design, and Factorial design.

INTERVENTION NAME

The intervention being studied.

INTERVENTION TYPE

The general category for the intervention being studied. Intervention types include Drug, Device, Biological, and Procedure.

INTERVENTIONAL STUDY (or Clinical Trial)

INVESTIGATOR

A researcher involved in a clinical study. Related terms include Site principal investigator, Site sub-investigator, Study chair, Study director, and Study principal investigator.

NO INTERVENTION ARM

A group of participants that does not receive any interventions during a clinical study. One of several Arm Types.

NOT YET RECRUITING

The clinical study has not started recruiting participants. A type of Recruitment Status.

OBSERVATIONAL STUDY

A clinical study in which participants identified as belonging to study groups are assessed for biomedical or health outcomes. Participants may receive diagnostic, therapeutic, or other types of interventions, but the investigator does not assign participants to specific interventions (as in an interventional study). A Study Type.

OBSERVATIONAL STUDY MODEL (Design)

The general design, describing the strategy for identifying and following up with participants during observational studies. Types of observational study models include Cohort, Case-control, Case-only, Case-crossover, Ecologic or community studies, Family-based, and Other.

OPEN LABEL

Describes a clinical trial in which masking is not used. That means that all parties involved with the trial know which participants have been assigned which interventions.

OPEN STUDIES

Studies that are currently recruiting participants, will be recruiting participants in the future, or involve drugs that are available for expanded access. Recruitment statuses for open studies are:

Recruiting
Not yet recruiting
Available for expanded access

OTHER ADVERSE EVENT

An adverse event that is not a serious adverse event.

OUTCOME MEASURE

A planned measurement described in the protocol that is used to determine the effect of interventions on participants in a clinical trial. For observational studies, a measurement or observation that is used to describe patterns of diseases or traits, or associations with exposures, risk factors, or treatment. Types of outcome measures include Primary Outcome Measure and Secondary Outcome Measure.

PARALLEL DESIGN

Describes a clinical trial in which two or more groups of participants receive different interventions. For example, a two-arm parallel design involves two groups of participants. One group receives drug A, and the other group receives drug B. So during the trial, participants in one group receive drug A "in parallel" to participants in the other group receiving drug B. One type of Intervention Model (Design).

PARTICIPANT FLOW

A summary of the progress of participants through each stage of a clinical study, by study arm. This includes the number of participants who started, completed, and dropped out of the study.

PHASE

Categories for describing the clinical trial of a drug based on the study's characteristics, such as the objective and number of participants. There are five phases:

Phase 0: Exploratory study involving very limited human exposure to the drug, with no therapeutic or diagnostic goals (for example, screening studies, microdose studies).

Phase 1: Studies that are usually conducted with healthy volunteers and that emphasize safety. The goal is to find out what the drug's most frequent and serious adverse events are and, often, how the drug is metabolized and excreted.

Phase 2: Studies that gather preliminary data on effectiveness (whether the drug works in people who have a certain disease or condition). For example, participants receiving the drug may be compared with similar participants receiving a different treatment, usually an inactive substance (called a placebo) or a different drug. Safety continues to be evaluated, and short-term adverse events are studied.

Phase 3: Studies that gather more information about safety and effectiveness by studying different populations and different dosages and by using the drug in combination with other drugs.

Phase 4: Studies occurring after drug is approved for marketing. These including postmarket requirement and commitment studies that are required of or agreed to by the sponsor. These studies gather additional information about a drug's safety, efficacy, or optimal use.

PLACEBO

A substance that does not contain active ingredients and is made to be physically indistinguishable (that is, it looks and tastes identical) from the actual drug being studied.

PLACEBO COMPARATOR ARM

A group of participants that receives a placebo during a clinical study. One of several Arm Types.

PRIMARY COMPLETION DATE

The date that the last participant in a clinical study was examined or received an intervention and that data for the primary outcome measure were collected. Whether the clinical study ended according to the protocol or was terminated does not affect this date. The "estimated primary completion date" is the date that the researchers think will be the primary completion date for the study.

PRIMARY OUTCOME MEASURE

The planned outcome measure in the protocol that is the most important for evaluating the effect of an intervention. Most clinical studies have one primary outcome measure, but some may have more than one.

PRIMARY PURPOSE

The one main reason for the clinical trial. Types of primary purposes include treatment, prevention, diagnostic, supportive care, screening, health services research, and basic science.

PRINCIPAL INVESTIGATOR (PI)

The person who is responsible for the scientific and technical direction of the entire clinical study (for example, for all sites of a multisite study).

PROTOCOL

The written description of a clinical study. It includes the study's objectives, design, and methods. It may also include relevant scientific background and statistical information.

PUBLICATIONS

Published scientific articles or abstracts about a clinical study.

RANDOMIZED ALLOCATION

A strategy in which participants are assigned to arms of a clinical trial by chance. A type of Allocation.

RECRUITING

The clinical study is currently recruiting participants. A type of Recruitment Status.

RECRUITMENT STATUS

Indicates the current stage of a clinical study and whether it is or will be open for enrollment. The possible recruitment statuses are:

Open Studies

Not yet recruiting
Recruiting
Available for expanded access

Closed Studies

Active, not recruiting
Completed
Terminated
Suspended
Withdrawn
Enrolling by invitation
Temporarily not available for expanded access
No longer available for expanded access
Approved for marketing

REGISTRATION

The process of submitting and updating summary information about a clinical study protocol from its beginning to end, to a structured, Web-based registry that is accessible to the public.

REGISTRY

A structured online system, that provides the public with access to summary information about ongoing and completed clinical studies.

REPORTING (OR COMPARISON) GROUP

A grouping of participants in a clinical study that is used in summarizing the data collected during the study. This grouping may be the same as or different from a study arm.

RESULTS DATABASE

A structured online system, that provides the public with access to summary results and registration information for completed or terminated clinical studies.

RESULTS SUBMISSION

The process of submitting and updating summary information about the results of a clinical study to a structured, public Web-based results database.

SECONDARY OUTCOME MEASURE

A planned outcome measure in the protocol that is not as important as the primary outcome measure, but is still of interest in evaluating the effect of an intervention. Most clinical studies have more than one secondary outcome measure.

SERIOUS ADVERSE EVENT

An adverse event that results in death, is life-threatening, requires inpatient hospitalization or extends a current hospital stay, results in an ongoing or significant incapacity or interferes substantially with normal life functions, or causes a congenital anomaly or birth defect. Medical events that do not result in death, are not life-threatening, or do not require hospitalization may be considered serious adverse events if they put the participant in danger or require medical or surgical intervention to prevent one of the results listed above.

SHAM COMPARATOR ARM

A group of participants that receives a procedure or device that is made to be indistinguishable from the actual procedure or device being studied but does not contain active processes or components. One of several Arm Types.

SINGLE BLIND MASKING

A type of masking in which one party involved with the clinical trial, either the investigator or participant, does not know which participants have been assigned which interventions.

SINGLE GROUP DESIGN

Describes a clinical trial in which all participants receive the same intervention. One type of Intervention Model (Design).

SPONSOR (LEAD)

The organization or person (see Sponsor-Investigator) who oversees the clinical study and is responsible for analyzing the study data.

SPONSOR-INVESTIGATOR

The person who both initiates and conducts the clinical study.

STUDY COMPLETION DATE

The date that the final data for a clinical study were collected because the last study participant has made the final visit to the study location (that is, "last subject, last visit"). The "estimated study completion date" is the date that researchers think will be the completion date for the study.

STUDY DESIGN

The investigative methods used in the clinical study. For interventional studies, these include Primary Purpose, Intervention Model (Design), Masking (or Blinding), and Allocation.

STUDY START DATE

The date that the enrollment of participants for a clinical study begins.

STUDY TYPE

Describes the nature of a clinical study. Study types include Interventional Studies (or Clinical Trials), Observational Studies, and Expanded Access.

SUSPENDED

The clinical study has stopped recruiting or enrolling participants early, but it may start again. A type of Recruitment Status.

TERMINATED

The clinical study has stopped recruiting or enrolling participants early and will not start again. Participants are no longer being examined or treated. A type of Recruitment Status.

TIME FRAME, OUTCOME MEASURE

The points in time at which the outcome measure is assessed. These are planned before the clinical study starts and listed in the protocol.

WITHDRAWN

The clinical study stopped before enrolling its first participant. A type of Recruitment Status.

ClinicalTrials.gov (01/Jan/2014)

Clinical Trials Database

Database of publicly and privately supported recruiting clinical studies of human participants in the Czech Republic (service of the U.S. National Institutes of Health):

Clinical Trials Database reports | ClinicalTrials.gov