Conclusion
To conclude, RCTs with a no-treatment arm, low funding, low financial
compensation per included patient are more likely to experience
recruitment failure, while a preceding pilot study lowers this chance.
We propose that investigators and grant providers consider these issues
before the actual start of the study, to improve the chances of
recruitment success. If a relevant trial is destined to have a suspected
long recruitment period, it seems wise to ponder on the question whether
to start the trial, or to accept a longer recruitment period with all
its consequences.