The Participant You Cannot Reach

Part of Decentralized Trials (DCT) Training: Verifying Who You Are Talking To.

About 2 minutes. Free, in your language, no account needed.

Silence is data, and it needs a response

A participant who does not answer is not automatically lost. They may be unwell, away, having device trouble, or in difficulty.

The one thing you cannot do is nothing.

Follow the escalation the protocol sets

Most studies specify the contact attempts: how many, by what channels, over what period, before a participant is considered unreachable.

Follow it exactly and record each attempt with date, time and channel. A log showing four attempts across three channels over eight days is a study doing its job.

Vary the channel

A phone that is not answered may be a broken phone. Try the other numbers, email, and any contact the participant nominated.

Consider the safety reading

If the last contact suggested a safety concern, or a device stopped transmitting abruptly, or a scheduled dose was missed, silence means something different.

Escalate to the investigator rather than continuing routine contact attempts. A welfare concern is not a retention problem.

Do not stop the clock on the protocol

While you are trying to reach them, visit windows continue and doses may be due. Missed visits are recorded as missed, with the reason.

When contact resumes

Find out what happened before resuming the schedule. There may be an adverse event, a hospitalization, or a period of non-adherence that needs recording.

The gap itself is often the most clinically interesting part of the record.

When it does not resume

The protocol will define how and when a participant is considered lost to follow-up. Applying it requires that the contact attempts were documented, which is why the log matters from the first missed call rather than from the point somebody decides it is serious.