Investigating if changing the wording of a study invitation letter increased recruitment in a project promoting tobacco cessation in a town with high smoking rates

Invitation letters can be the first point of contact between research staff and potential participants and a number of modifiable variables have been studied to improve their effectiveness. The aim of this analysis was to determine if lower reading levels and “gain-framed” messages improved recruitment for a RCT that mailed nicotine replacement therapy (NRT) patches for smoking cessation. Invitation letters were created which varied in a two-by-two design by reading level and message framing. The letters were randomly mailed to all households in a community selected to receive targeted distribution of NRT patches. There were no significant differences found in the number of participants enrolled. Future research investigating factors to improve invitation letters is merited despite current project limitations. ClinicalTrials.gov NCT04534231.