Clinical Research

Types of Clinical Research 

• • Epidemiology studies improve the understanding of a disease by studying patterns, causes, and effects of health and disease in specific groups of people.
  • Behavioral studies improve the understanding of human behavior and how it relates to health and disease.
  • Health services studies examine how people access health care providers and health care services, how much care costs, and what happens to patients as a result of the care they receive.
  • Quality of Life Research explores ways to improve comfort and the quality of life for individuals with a chronic illness.
  • Community-based participatory research engages the local community in all phases of the research process.
  • Genetic studies examine the potential role of genes in different diseases.
  • Observational studies observe a group of people for many years, usually without any specific intervention. These studies can help scientists understand the natural history of a disease or the transition from wellness to illness.
  • Physiological studies attempt to shed more light on how the human body functions.
  • Public health research tries to improve the health and well-being of people from a population-level perspective. It may combine one or more types of clinical research.
  • Clinical trials prospectively assign one or more human subjects to one or more interventions (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes.

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Clinical Trials

Clinical Trials are research studies in which one or more human subjects are prospectively assigned to one or more interventions (which may include placebo or other control) to evaluate the effects of those interventions on health-related biomedical or behavioral outcomes. 

The term prospectively assigned refers to a pre-defined process (e.g., randomization) specified in an approved protocol that stipulates the assignment of research subjects (individually or in clusters) to one or more arms (e.g., intervention, placebo, other control) of a clinical trial.

An intervention is defined as a manipulation of the subject or the subject's environment for the purpose of modifying one or more health-related biomedical or behavioral processes and/or endpoints. Examples include drugs/small molecules/compounds, biologics, devices, procedures (e.g., surgical techniques), delivery systems (e.g., telemedicine, face-to-face interviews), strategies to change health-related behavior (e.g., diet, cognitive therapy, exercise, development of new habits), treatment strategies, prevention strategies, and diagnostic strategies.

Health-related biomedical or behavioral outcome is defined as the pre-specified goal(s) or condition(s) that reflect the effect of one or more interventions on human subjects' biomedical or behavioral status or quality of life. Examples include positive or negative changes to physiological or biological parameters (e.g., improvement of lung capacity, gene expression), positive or negative changes to psychological or neurodevelopmental parameters (e.g., mood management intervention for smokers, reading comprehension and/or information retention), positive or negative changes to disease processes, positive or negative changes to health-related behaviors, and positive or negative changes to quality of life.

There are different types of clinical trials.

• • Prevention trials look for better ways to prevent a disease in people who have never had the disease or to prevent the disease from returning. Approaches may include medicines, vaccines, or lifestyle changes.
  • Screening trials test new ways for detecting diseases or health conditions.
  • Diagnostic trials study or compare tests or procedures for diagnosing a particular disease or condition.
  • Treatment trials test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
  • Behavioral trials evaluate or compare ways to promote behavioral changes designed to improve health.
  • Quality of life trials (or supportive care trials) explore and measure ways to improve the comfort and quality of life of people with conditions or illnesses. 

Clinical trials are conducted in a series of steps called “phases.” Each phase has a different purpose and helps researchers answer different questions.

• • Phase I trials: Researchers test a drug or treatment in a small group of people (20–80) for the first time. The purpose is to study the drug or treatment to learn about safety and identify side effects.
  • Phase II trials: The new drug or treatment is given to a larger group of people (100–300) to determine its effectiveness and to further study its safety.
  • Phase III trials: The new drug or treatment is given to large groups of people (1,000–3,000) to confirm its effectiveness, monitor side effects, compare it with standard or similar treatments, and collect information that will allow the new drug or treatment to be used safely.
  • Phase IV trials: After a drug is approved by the FDA and made available to the public, researchers track its safety in the general population, seeking more information about a drug or treatment’s benefits, and optimal use.