Introduction
knee osteoarthritis, OA, word of mouth
RECRUITMENT, KNEE OSTEOARTHRITIS
Investigators traditionally recruit participants for clinical research using flyers, print and broadcast media, and word of mouth. Use of web-based recruitment methods have grown over the past 20 years with the inception of social media [A major gap in planning for web-based physical therapy intervention studies is that little is known about the extent to which reach and clicks on advertisements translate to actual consent and enrollment of participants who meet study criteria, and the costs associated with recruitment. Reach is the number of unique people who have seen a post on Facebook [The primary aim of this study was to report on the conversion of reach and clicks from a Facebook advertising campaign to enrollment defined as electronically signing the study informed consent form (ICF) in an ongoing nationwide telehealth physical therapy study for adults with knee osteoarthritis (OA) within the United States. Secondarily, recruitment costs, geographic characteristics, age, and sex were described for reach, clicks, and consent from advertisements.