Does a valid identifier format prove a correct match?

No. Format checks do not establish that a code identifies the intended participant; its authoritative relationship must also be tested.

Should a corrected code erase the earlier link?

Correct affected relationships while retaining the reason and change history rather than making the original association disappear.

Participant Identifier Crosswalks: Preventing Wrong-Person Linkage

Published: 28 October 2026
Updated: 28 October 2026

Laboratory, imaging and EDC systems may assign different identifiers to the same participant. One crosswalk error can attach an otherwise correct measurement to the wrong study record while passing routine format checks.

Preserve the meaning of data

Define who creates each identifier, which authoritative source confirms it, and how corrections propagate. Avoid copying direct identifiers merely to simplify reconciliation. Separate links verified against an authorised local identity record from pseudonymous codes used by the sponsor. Consider that identical-looking codes may refer to different participants at different sites.

Worked example

For example, two sites each use participant code 001. A transfer keeps only the last three digits and merges their results. In this example, site and study identifiers become part of the matching key, and earlier transfers are compared against authorised records in a controlled review. Repairing only the next incoming file would leave historical errors unresolved.

Review checks

Test the uniqueness boundary at both study and site levels.
Independently sample newly created and corrected identifier links.
Trace the effect of incorrect links into historical reports.

Acceptance and boundaries

Acceptance means a selected result can be traced back to the correct pseudonymous study record. Teams without a legitimate need should not need access to local identity links. This operational example does not prescribe one privacy arrangement for every jurisdiction. Responsible parties should assess crosswalk access within the approved study arrangements and applicable requirements.

Frequently asked questions

Does a valid identifier format prove a correct match?: No. Format checks do not establish that a code identifies the intended participant; its authoritative relationship must also be tested.
Should a corrected code erase the earlier link?: Correct affected relationships while retaining the reason and change history rather than making the original association disappear.