Comparator is a well-established concept in clinical trial design and appears frequently in:

• ICH guidelines (especially E6, E9, E10),
• trial protocols,
• statistical analysis plans,
• regulatory submissions,
• clinical study reports.

It’s also a term that junior CRAs and investigators sometimes misunderstand, equating it only with an active control.

A glossary entry can clarify that a comparator is broader and may include:

• placebo,
• active control,
• standard of care,
• no treatment (in some designs),
• historical or external control (depending on context).