Study ConductGlossary Term
ICH E6(R3) Section 6.4
A procedure in which one or more parties involved in the trial are kept unaware of the treatment assignment to reduce bias in the assessment of outcomes.
Blinding, also called masking, is a methodological technique designed to minimize bias in clinical trial results by preventing knowledge of treatment assignments from influencing behavior or assessments. When successful, blinding ensures that expectations about treatment effects do not consciously or unconsciously affect how participants report symptoms, how investigators evaluate outcomes, or how data analysts interpret results. This protection against bias is essential for generating credible evidence about treatment effects.
Single-blind trials typically keep participants unaware of their treatment assignment while investigators know which treatment each participant receives. Double-blind trials extend this protection to include the investigator and often the study personnel conducting assessments. Triple-blind designs additionally mask the treatment assignment from data analysts, data monitoring committees, or other parties. The appropriate level of blinding depends on the nature of the endpoints being assessed and the feasibility of maintaining the blind given the characteristics of the treatments being compared.
Maintaining the blind throughout a trial requires careful attention to many details. Investigational products and placebo must be identical in appearance, taste, smell, and packaging. Procedures must prevent inadvertent unblinding through laboratory values, side effects, or other clues. Emergency unblinding procedures must be available when knowledge of treatment assignment is medically necessary, but these procedures must be carefully controlled to prevent inappropriate unblinding. The integrity of blinding should be assessed, as premature or frequent unblinding can compromise the validity of trial results.
Double-blind trial
"In the double-blind Phase III trial, identical capsules containing either active drug or placebo were dispensed, and neither the participants nor the site staff knew which treatment was being administered."
Emergency unblinding
"When the participant presented to the emergency department with severe symptoms, the treating physician called the emergency unblinding line to obtain the treatment assignment, which was necessary for appropriate medical management."
A professional employed by the sponsor or contract research organization who monitors clinical trials at investigational sites to ensure protocol compliance, data quality, and participant safety.
A specialized research professional who works at the investigational site under the supervision of the investigator to coordinate and manage the day-to-day operational aspects of clinical trials.
The act of overseeing the progress of a clinical trial and ensuring that it is conducted, recorded, and reported in accordance with the protocol, standard operating procedures, GCP, and applicable regulatory requirements.
Any change, divergence, or departure from the study design or procedures defined in the protocol that is not implemented through a formal protocol amendment.
The process of assigning trial subjects to treatment or control groups using an element of chance to reduce bias in allocating interventions.
ICH E6(R3) Section 6.4
A procedure in which one or more parties involved in the trial are kept unaware of the treatment assignment to reduce bias in the assessment of outcomes.
Blinding, also called masking, is a methodological technique designed to minimize bias in clinical trial results by preventing knowledge of treatment assignments from influencing behavior or assessments. When successful, blinding ensures that expectations about treatment effects do not consciously or unconsciously affect how participants report symptoms, how investigators evaluate outcomes, or how data analysts interpret results. This protection against bias is essential for generating credible evidence about treatment effects.
Single-blind trials typically keep participants unaware of their treatment assignment while investigators know which treatment each participant receives. Double-blind trials extend this protection to include the investigator and often the study personnel conducting assessments. Triple-blind designs additionally mask the treatment assignment from data analysts, data monitoring committees, or other parties. The appropriate level of blinding depends on the nature of the endpoints being assessed and the feasibility of maintaining the blind given the characteristics of the treatments being compared.
Maintaining the blind throughout a trial requires careful attention to many details. Investigational products and placebo must be identical in appearance, taste, smell, and packaging. Procedures must prevent inadvertent unblinding through laboratory values, side effects, or other clues. Emergency unblinding procedures must be available when knowledge of treatment assignment is medically necessary, but these procedures must be carefully controlled to prevent inappropriate unblinding. The integrity of blinding should be assessed, as premature or frequent unblinding can compromise the validity of trial results.
Double-blind trial
"In the double-blind Phase III trial, identical capsules containing either active drug or placebo were dispensed, and neither the participants nor the site staff knew which treatment was being administered."
Emergency unblinding
"When the participant presented to the emergency department with severe symptoms, the treating physician called the emergency unblinding line to obtain the treatment assignment, which was necessary for appropriate medical management."
A professional employed by the sponsor or contract research organization who monitors clinical trials at investigational sites to ensure protocol compliance, data quality, and participant safety.
A specialized research professional who works at the investigational site under the supervision of the investigator to coordinate and manage the day-to-day operational aspects of clinical trials.
The act of overseeing the progress of a clinical trial and ensuring that it is conducted, recorded, and reported in accordance with the protocol, standard operating procedures, GCP, and applicable regulatory requirements.
Any change, divergence, or departure from the study design or procedures defined in the protocol that is not implemented through a formal protocol amendment.
The process of assigning trial subjects to treatment or control groups using an element of chance to reduce bias in allocating interventions.