- Published
- Updated
The version, accessory and settings of a comparator matter alongside its model. An inadequately defined comparator can leave uncertainty about whether an observed difference comes from the device or the conditions of use. Link the choice to the investigation question.
Define the assessment
Explain the clinical option represented, its availability during the study and users’ experience with it. Current standard practice should not automatically be equated with a single commercial product. Where practice differs between sites, assess implications for design and interpretation.
Worked example
For example, a new imaging device is compared with an older system version. Updated comparator software becomes common during recruitment. Before changing versions, the team examines what comparison the question requires, whether the update alters measurement and how current the comparison remains. It documents the technical and clinical reasons for the decision.
Practical checks
- Define comparator model, version, accessories and important settings in the investigation plan.
- Assess potential differences in training and procedural experience between the comparison groups.
- Track data periods and assessment decisions if the comparator changes during conduct.
Decision and limitations
A reader should understand which real clinical alternative the comparison represents. Avoid extending conclusions to every unexamined comparator version. An ageing comparison may remain informative, but its context and limits of inference should be explained.
Frequently asked questions
- Is the most common product always the right comparator?
- No. Justify selection against the scientific question, clinical context and ethical assessment.
- Should the study immediately adopt a new version?
- Not automatically. Assess design, safety, technical impact and applicable approval requirements together.