trial [tri´al, trīl]
a test or experiment.
an experiment performed on human beings in order to evaluate the comparative efficacy of two or more therapies. See also single blind
, double blind
, and triple blind
a controlled experiment involving a defined set of human subjects, having a clinical event as an outcome measure, and intended to yield scientifically valid information about the efficacy or safety of a drug, vaccine, diagnostic test, surgical procedure, or other form of medical intervention.
Four phases of clinical trial are distinguished. Phase I trials usually involve fewer than 100 healthy volunteers who are exposed to a new drug or procedure. Such studies seek to establish optimal dosage and route of administration and to detect adverse reactions. Phase II trials generally involve 200-500 volunteers randomly assigned to control and study groups. These are pilot efficacy studies, with emphasis on immunogenicity in the case of vaccines, and on relative efficacy and safety in the case of drugs, procedures, and devices. Phase III trials, often multicenter, involve thousands of volunteers, randomly assigned to control and study groups. The aim is to generate statistically relevant data. Phase IV trials are conducted after a national drug registration authority (in the U.S., the Food and Drug Administration) has approved an agent for distribution or sale. They may explore specific pharmacologic effects, adverse reactions, or long-term effects.
A research study using consenting human subjects that tests the effectiveness and safety of a treatment, a diagnostic tool, or a prophylactic intervention.
clinical trial A research study involving human subjects designed to answer specific questions about the safety and efficacy of a biomedical intervention (drug, treatment, device), or new ways of using a known drug, treatment or device.
clinical trial Clinical medical trial, clinical research trial Research A controlled study involving human subjects, designed to evaluate prospectively the safety and effectiveness of new drugs or devices or behavioral interventions. See Drug discovery, IND, Phase I, II, and III studies.
clin·i·cal trial (klini-kăl trīăl)
A controlled experiment involving a defined set of human subjects, having a clinical event as an outcome measure, and intended to yield scientifically valid information about the efficacy or safety of a drug, vaccine, diagnostic test, surgical procedure, or other form of medical intervention.
clinical trial a scientifically controlled study under specific conditions, to test, for example, the effectiveness of a drug/ treatment.
All new drugs undergo clinical trials before approval. Clinical trials are carefully conducted tests in which effectiveness and side effects are studied, with the placebo effect eliminated.
trial, randomized controlled (RCT)
An experimental design used for testing the effectiveness of a new medication or a new therapeutic procedure. Individuals are assigned randomly to a treatment group (experimental therapy) and a control group (placebo or standard therapy) and the outcomes are compared. The trial is strengthened by 'blinding' or masking (single-blind, double-blind or triple-blind study) and cross-over design. RCT is the most accepted scientific method of determining the benefit of a drug or a therapeutic procedure. It represents the best evidence available, which is integrated into the final decision about the management of a condition by healthcare practitioners in what is called evidence-based healthcare
. randomized clinical trial. See sampling
n a trial based upon the scientific method in which a control group and a test group are compared over time in order to study a single, differing factor.