In every clinical trial, there is a critical risk that doesn’t get enough attention: what happens when you can’t reach a participant anymore?
This is “lost to follow-up,” and it threatens the integrity of your data. And here’s the part that many sponsors and sites discover too late: whether you can legally and ethically ask for outside help to find that missing participant often comes down to what your informed consent form (ICF) says.
Here, we’ll explain why strong informed consent language is essential to minimize lost to follow-up and how OmniTrace supports sponsors, CROs, and sites when standard methods to reach participants fail.
Why lost to follow-up is such a threat
Lost to follow-up (LTFU) is not just an operational headache. It has scientific and regulatory consequences.
When a participant disappears, you can lose:
- Safety data
- Efficacy/end point data
- Survival / vital status
- Long-term follow-up required by protocol
Regulators know this is a real risk. U.S. guidance makes two things very clear: (1) data collected before withdrawal stays in the study database; and (2) even if a participant does not consent to additional active follow-up, sponsors and investigators may still consult public records to determine basic survival status — but they cannot keep accessing that participant’s medical record for study purposes without permission.
That matters because you must be able to say: “We know what happened to our participants.” Missing outcome data weakens safety conclusions, dulls efficacy signals, and opens the door for questions you do not want from regulators, investigators, or future partners.
Simply put, high LTFU rates make your trial look sloppy and potentially underpowered. Strong informed consent language reduces that risk.
Where informed consent language goes wrong
Most underperforming ICFs fail for the same reasons:
- Vague “third-party” language
You’ll sometimes see: “We may share your information with third parties as needed.”
That’s too broad. It doesn’t define what is shared, who it is shared with, for what purpose, or with what privacy controls. Ethics committees push back on it, and operationally it may not be enough to allow you to use a specialized locator service like OmniTrace. - No post-withdrawal clarity
Many ICFs still say (or strongly imply): “If you withdraw, all follow-up stops and your data will be deleted.”
That isn’t how regulators expect research to work. Data already collected typically remains part of the trial record. The ICF should explain that fact transparently, and it should give the participant a choice about limited ongoing follow-up (for example, allowing the site to confirm survival status later). - No consent for a locator
The single biggest blocker is that the ICF never actually authorizes the site to share limited identifying information (such as name, date of birth, last known address, or last known phone number) with a qualified third-party service for the purpose of locating the participant or confirming survival status through publicly available records. If that language isn’t there, many sites simply cannot engage outside help. - Cross-border gaps
In the EU and UK especially, it is not enough to say “your data may be transferred overseas.” Ethics committees expect you to explain how you’ll protect identifiers if they leave the country (for example, using Standard Contractual Clauses when data is accessed in the U.S.). If you skip that, you may not be allowed to involve a U.S.-based support service at all.
In other words: the most common LTFU failures are not about effort. They’re about paperwork.
What good informed consent language looks like
A well-written ICF does a few simple but powerful things:
1. It tells the participant why continued follow-up matters.
For example:
“It is important for the study doctor to understand your health status over time, including serious health events and, when applicable, survival status. This information helps evaluate safety and effectiveness and is required for regulatory and scientific reasons.”
This frames follow-up as responsible, not intrusive.
2. It authorizes limited data sharing — and only for a specific purpose.
For example:
“If we cannot contact you after reasonable attempts, we may share your name, date of birth, and last known contact information with a licensed clinical trial support service. This service may use publicly available records to obtain updated contact information or confirm your survival status. The service will not contact you or your family directly, and will not share your personal identifying information with the study sponsor.”
Now you’ve defined:
- What data may be shared
- With whom
- Why
- What they will not do (no direct outreach)
- Who will not get identifiers (the sponsor)
Ethics committees appreciate that specificity. So do privacy officers.
3. It explains what happens if the participant withdraws.
For example:
“If you leave the study, data collected before withdrawal will remain part of the study results. You may choose whether we continue limited follow-up (for example, confirming survival status). If you decline, we will not review your medical records for study purposes after withdrawal. We may still review public records to determine your survival status.”
This language does three important jobs at once:
- Confirms that already-collected data stays in the trial
- Offers a choice about continued follow-up
- Makes the regulatory boundary very clear
4. In EU/UK settings, it addresses international data transfer.
For example:
“If it becomes necessary to transfer your identifying information outside your country (for example, to a support service based in the United States), this will be done under approved legal safeguards designed to provide equivalent protection for your personal information. You may choose whether to allow this.”
That last sentence matters. In many European jurisdictions, giving the participant a checkbox for cross-border transfer is what allows you to work with a U.S.-based service at all.
How OmniTrace supports sites and sponsors
OmniTrace is a licensed investigative and clinical trial support service that focuses on ethically re-establishing contact with participants, or confirming vital / survival status, when normal site-driven outreach stops working.
In practice, that means:
- We work for the site, not the sponsor.
We do not provide personal identifiers to the sponsor. We report back to the investigator or site study team. - We use compliant, legally permissible sources.
We rely on public records and other allowed sources to update addresses, confirm relocation, or determine if the participant is deceased. - We do not contact the participant or their family directly unless the ICF and local rules explicitly allow it (and in most trials, they do not).
This protects the participant relationship. Communication continues to come from the study doctor. - We document what we found, how we found it, and when.
That audit trail helps you justify your follow-up efforts to regulators, data monitoring committees, internal QA, or future due diligence.
When informed consent language is written correctly, engaging OmniTrace is simple and fast for the site. When informed consent language is vague, incomplete, or non-compliant, every additional step becomes slower, more expensive, and more challenging.
From a scientific standpoint, high LTFU weakens your data. It becomes harder to prove safety, survival, durability of response, disease progression timing, or even final status at database lock.
From a regulatory standpoint, uncontrolled LTFU invites questions. Why did you lose these participants? Did you obtain permission to continue passive follow-up? Did you take appropriate steps to confirm vital status?
From a legal/ethics standpoint, consent language is what lets you balance “we must know what happened” with “we respect your choice.” That balance is what IRBs, ethics committees, data privacy officers, and health authorities expect you to demonstrate.
Well-drafted informed consent language lets you do exactly that.
Conclusion: set yourself up for success now, not when it’s too late
Lost to follow-up will happen. Participants move. They change numbers. They disengage from the site. Some formally withdraw.
The question is not whether this will happen in your trial, but how prepared you will be when it does.
If your informed consent language:
- clearly explains why continued follow-up matters,
- authorizes a licensed third-party to assist with finding updated contact information or survival status,
- respects the participant’s choices after withdrawal, and
- protects privacy and data handling across borders,
then you are protecting your data, your timelines, and your credibility.
OmniTrace works with sponsors, CROs, and sites to build that readiness up front and to step in when participants become hard to find. If you would like an evaluation of your current wording, or help strengthening future ICFs so they meet regulatory expectations and reduce LTFU risk, we’re here to help.
Key Takeaways
- Lost to follow-up isn’t just annoying — it can damage scientific credibility and regulatory defensibility.
- Most LTFU headaches are preventable with clear informed consent language.
- Your ICF should authorize limited data sharing with a licensed third-party support service to help confirm updated contact info or survival status through public records.
- Good language also describes what happens after withdrawal and addresses cross-border data protection.
- Strong language now means fewer scramble situations later — and OmniTrace can help you get there.
