While we’re not allowed to coerce people into taking part in trials, there are things we can highlight that should help encourage interest, at least. The fact the participant is ‘doing good’ is certainly one of these things. Plus some trials will cover expenses or even arrange for transport and accommodation.
One of the things I think participating in a trial provides that is often undersold is the level of basic health check care that people will receive.
The potential new treatment is being investigated for its efficacy in relation to a specific condition. Such that while someone is in a trial, multiple other general health checks are regularly provided to ensure the accuracy of the results.
In effect, what you’re getting when on trial is the equivalent of a ‘well person’ health check on a regular basis – provided as a matter of course, rather than having to pay for it.