Open-Label Extension (OLE)
A study phase following a blinded RCT in which all participants receive the active treatment and are monitored for long-term safety and efficacy.
In Depth
OLEs provide long-term safety data that short-term RCTs cannot. The Epidiolex OLE studies followed patients for up to 4 years, providing evidence of sustained seizure reduction and long-term safety. OLE data must be interpreted cautiously: participants who complete the blinded phase and enroll in OLEs may not represent the full trial population (selection bias), and the lack of a control group limits efficacy conclusions.
More in Research Methods
Randomized Controlled Trial (RCT)
The gold standard study design in clinical research. Participants are randomly assigned to treatment or control groups to minimize bias and establish causation.
Systematic Review
A structured synthesis of all available evidence on a specific research question, using predefined criteria to identify, evaluate, and summarize studies.
Meta-Analysis
A statistical technique that combines quantitative data from multiple studies to produce a pooled estimate of effect size with greater statistical power than any individual study.
Placebo-Controlled
A study design in which the control group receives an inert substance (placebo) identical in appearance to the active treatment, to account for the placebo effect.
Observational Study
A study in which researchers observe participants without intervening. Includes cohort studies, case-control studies, and cross-sectional surveys.