There are two main types of clinical studies: clinical trials and observational studies. Both involve using human participants to conduct research intended to enhance medical knowledge.
In a clinical trial, participants receive specific interventions according to the research protocol. These interventions may be medical products, or changes to participants' behavior, such as activity or 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. Some clinical trials compare interventions that are already commercially available. When a new product or approach is being studied, investigators try to determine the safety and effectiveness of the intervention by monitoring certain outcomes in the participants. Prior to the trial, it is typically not known whether the intervention will be helpful, harmful, or no different than available alternatives.
Clinical trials used in drug development are often conducted in phases to ensure a thorough investigation. There are four different phases:
In an observational study, investigators assess health outcomes in groups of participants according to a research plan or protocol. Participants may receive interventions or procedures as part of their routine medical care, but they 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.
Every clinical study is led by a principal investigator (PI), 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, in addition to Federal agencies such as the National Institutes of Health, the U.S. Department of Defense, and the U.S. Department of Veterans Affairs. Doctors, other health care providers, and other individuals can also sponsor clinical research.
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.
The duration of a clinical study varies greatly depending on the research they are conducting.
Clinical studies are designed to enhance medical knowledge related to the treatment, diagnosis, and prevention of diseases or conditions
A clinical study is conducted according to a research plan known as the protocol, designed to answer specific research questions and safeguard the health of participants. It contains the following information:
Volunteers cannot participate in any clinical study they choose. There are standards called eligibility criteria and are listed in the protocol. While some research studies seek participants who have the illnesses or conditions that will be studied, other studies are looking for healthy participants. The factors that allow someone to participate in a clinical study are called inclusion criteria, and the factors that disqualify someone from participation are called exclusion criteria. Inclusion and exclusion criteria may be based on age, gender, previous treatment history, and other medical conditions.