Return to sender: why sending your trial participants Christmas cards may not keep them merry and bright

Researchers from the University of York (UK) have found that sending Christmas cards to participants is unlikely to lead to higher retention rates. Published in the Christmas issue of BMJ, the researchers utilized a study within a trial (SWAT) approach to assess whether receiving a festive greeting kept participants as sweet as a mince pie. The team sought the opportunity to spread Christmas cheer in December 2019 by finding patients who had yet to receive a follow-up on their host randomized clinical trial (RCT). Some were sent Christmas cards, while others did not (not even a piece of coal!). However, the festivities made little...