Results
A total of 7 advertisement campaigns were conducted on Facebook from July to November 2021, each lasting an average of 4 days. In sum, 33,319 unique users across the 48 states in the contiguous United States saw at least one advertisement (reach). A total of 9879 clicks were made, and 423 (4.3%) screening forms were completed. Of those 9879 clicks, 336 (3.4%) participants passed the screening form criteria and 132 (1.3%) were successfully contacted by a research assistant (n=11, 0.1% did not provide contact information, and n=193, 1.96% could not be reached). Of the 9879 persons who clicked the advertisements, 70 (0.7%) were considered eligible, and 32 participants (0.3%) signed the ICF, which exceeded our enrollment target of 22 study participants within the first 5 study months. In particular, the ICF was signed by 12, 3, 4, 7, and 6 adults in the first 5 study months, respectively. This sample of 32 participants included 24 (75%) women, and the average age was 59.8 (SD 8.4) years (Of the 9879 clicks on the study advertisement, 32 (0.3%) were ultimately eligible. Campaigns cost a total of US $1661.97, and cost per consented participant was US $51.94. The 32 participants who were enrolled came from 17 (35.4%) of the possible 48 different states. In addition, it is important to note that people from all contiguous United States (48 states) were reached (Participants aged between 55 and 64 years had the highest reach, clicks, and consents followed by those aged >65, while those 45 to 54 years old had the lowest reach, clicks, and consent. In terms of sex, women had higher numbers of reach, clicks, and consents compared to men (Timeline between Facebook reach and clicks to consent.The US geographical representation.Facebook metrics by age groups and sex.