Objective Facebook (FB) ads are touted as a way to facilitate recruitment of hard to reach participants into digital health research but the evidence has been mixed. This study aimed to empirically evaluate the impact and cost-effectiveness of paid ads for recruitment into a national trial testing an Internet-based, coached intervention for parents of children with Fetal Alcohol Spectrum Disorders. Methods Post hoc analysis of FB ad data and Google analytics on the online trial consent site (myStudies) were conducted on 11 campaigns employing static image/text ads. Standard metrics (e.g., click through rate, cost per 1000 impressions, cost per consent) were calculated and descriptive statistics comparing FB ad engagement and enrolled participants over time were conducted. Results Ad campaigns were active for a combined 115 days over 58 weeks resulting in 1533 links to the online recruitment site. During the ad campaigns, the mean rate of enrolment was 1 participant every 2 days. The first 3 ad campaigns were the most cost-effective. Mean cost per enrolment was $19.27 (Canadian dollars). Conclusions FB ads were efficient and cost-effective in broad dissemination of trial information, but more research is needed to explore the impact of saturation (how often ads are posted), design (what is in the ad), and individual determinants (who is likely to respond to an ad) on converting FB ad engagement into enrolment. Avoiding a reductionist approach to analytics will help ensure appropriate and targeted strategies remain the priority for digital health research recruitment through social media.

中文翻译：

---

Facebook 广告来救场？招募难以接触的人群参加基于互联网的行为健康干预试验。

目标 Facebook (FB) 广告被吹捧为促进招募难以接触到的参与者参与数字健康研究的一种方式，但证据参差不齐。本研究旨在实证评估付费广告招募到一项全国性试验的影响和成本效益，该试验测试了一项针对胎儿酒精谱系障碍儿童父母的基于互联网的指导干预。方法 对 FB 广告数据和在线试验同意网站 (myStudies) 上的 Google 分析进行了事后分析，对 11 个使用静态图像/文本广告的活动进行了分析。计算了标准指标（例如，点击率、每 1000 次展示的成本、每次同意的成本），并进行了比较 FB 广告参与度和注册参与者随时间推移的描述性统计数据。结果 广告活动在 58 周内总共活跃了 115 天，产生了 1533 个指向在线招聘网站的链接。在广告活动期间，平均注册率为每 2 天 1 名参与者。前 3 个广告系列最具成本效益。每次注册的平均成本为 19.27 美元（加元）。结论 FB 广告在广泛传播试验信息方面是有效且具有成本效益的，但需要更多的研究来探索饱和度（广告发布的频率）、设计（广告中的内容）和个体决定因素（谁是可能会响应广告）关于将 FB 广告参与转化为注册。避免简化的分析方法将有助于确保适当和有针对性的策略仍然是通过社交媒体招募数字健康研究的优先事项。