Placebo-controlled trial

A clinical study that compares an intervention with an inactive or sham treatment designed to resemble it. The comparison helps separate an intervention’s effects from expectations and other influences.

Placebo: An inactive or sham intervention used as a control in research or clinical care. It is the comparator that gives this trial its defining feature.
Double-blind study: A study design in which participants and specified study personnel do not know treatment assignments. It is a common masking strategy for placebo comparisons.
No-treatment control: A comparison group that receives no study intervention or placebo. It does not reproduce the expectations and treatment context of a placebo group.
Clinical equipoise: Genuine professional uncertainty about which treatment in a trial is preferable. Uncertainty helps justify random assignment between placebo and an intervention.
Randomized controlled trial: A study that assigns participants by chance to intervention groups and compares their outcomes. Random allocation can balance groups in a placebo-controlled trial.
Sham surgery: A control procedure that mimics surgery without performing its intended therapeutic component. It enables placebo-like comparisons when an intervention is a surgical procedure.
Usual care: The standard clinical management ordinarily provided for a condition in a particular setting. Comparing with usual care estimates effects against routine practice, not an inert control.
Intention-to-treat analysis: An analysis that keeps participants in their originally assigned groups regardless of adherence or treatment changes. It preserves the randomized comparison, including in placebo-controlled trials.
Blinding (research): The withholding of group assignments from participants, clinicians, or researchers in a study. Masking can reduce behavior and assessment changes caused by knowing the assigned treatment.
Active-controlled trial: A trial that compares an intervention with an established treatment rather than an inactive control. It is used when withholding effective treatment makes a placebo-only comparison unsuitable.

Linked from 15 pages