Social Media Influencer Marketing as a Clinical Trial Recruitment Modality: Tutorial Informed by One Study's Approach.

Background: Influencer marketing (paid promotion by individuals with large, engaged social media followings) has become a major commercial advertising strategy, projected to reach US $32 billion globally in 2025. Clinical trials increasingly recruit through digital channels such as social media advertisements and patient portal messages. However, to our knowledge, influencer marketing has not been described as a clinical trial recruitment modality, and no practical guidance exists for investigators who wish to use it. Objective: We provide a step-by-step tutorial describing how we developed and deployed a social media influencer recruitment video for the GoFreshSE (Groceries for Residents of Southeastern USA to Stop Hypertension) trial, a decentralized pilot randomized trial of home-delivered Dietary Approaches to Stop Hypertension-pattern groceries for adults with elevated blood pressure in Florida, Georgia, and Tennessee. We also provide a reusable preparation framework for other study teams. Methods: Using Cameo Business, an online marketplace where public figures record short promotional videos, we filtered candidates by audience location (Atlanta, Miami, and Nashville), follower count (≥100,000), and price (US <$3000) and then selected an influencer on the basis of audience demographics relevant to our recruitment priorities. We transcribed the influencer's sample videos to characterize his speaking style, drafted a study script, and used a large language model (GPT-4o) solely to adapt the script's tone; the adapted script was reviewed by the study team and approved by the institutional review board before use. After the influencer recorded the video, we corrected gaze and adjusted pace using openly available tools, added framing and captions, and deployed the advertisement on Facebook and Instagram through Meta's advertising platform. Results: A qualifying pool of 57 influencers met our follower and cost thresholds. The selected influencer delivered a high-quality video 4 days after booking. The total Cameo cost was US $660, including a 75-day license and service fee, and the elapsed time from script development to a live advertisement was less than 2 months. The final 47-second video was rendered to satisfy Meta and TikTok placement and aspect ratio requirements while retaining the platform-required watermark. We report each step (marketplace search, booking request, script adaptation, ethics review, video editing, and deployment) in sufficient detail to be reproduced. Conclusions: Social media influencer marketing through Cameo Business is a rapid, low-cost mechanism for producing clinical trial recruitment videos and is feasible within typical trial timelines and budgets. To our knowledge, this is the first tutorial to document the procedure end to end, and it surfaces practical, ethical, and authenticity considerations, including governance of generative artificial intelligence and the limits of permissible video editing, that investigators should weigh before adopting this modality. The comparative effectiveness of influencer-based recruitment will be evaluated separately.