Using the Bing Ads system, we conducted an RCT to randomly expose the searchers for pro-ana content to 10 different ads referring people to one of the three websites: the National Eating Disorders Association, the National Institutes of Mental Health, and MyProAna. 
Bing Ads
Inducing Behavioral Change in Seekers of Pro-Anorexia Content Using Internet Advertisements: Randomized Controlled Trial.BACKGROUND
 The influence of pro-anorexia (pro-ana) websites is debated, with studies indicating both negative and positive effects, as well as significant variation in the effects of different websites for those suffering from eating disorders (EDs) and the general population.  Online advertising, known to induce behavioral change both online and in the physical world, has not been used so far to modify the search behavior of people seeking pro-ana content.


 The objective of this randomized controlled trial (RCT) was to examine if online advertisements (ads) can change online search behaviors of users who are looking for online pro-ana content.


 Using the Bing Ads system, we conducted an RCT to randomly expose the searchers for pro-ana content to 10 different ads referring people to one of the three websites: the National Eating Disorders Association, the National Institutes of Mental Health, and MyProAna.  MyProAna is a pro-ana website that was found in a previous study to be associated with less pathological online behaviors than other pro-ana websites.  We followed participants exposed and unexposed to the ads to explore their past and future online searches.  The ads were shown 25,554 times and clicked on 217 times.


 RESULTS
 Exposure to the ads was associated with a decrease in searches for pro-ana and self-harm content.  Reductions were greatest among those referred to MyProAna (reduction of 34.0% [73/215] and 37.2% [80/215] for pro-ana and self-harm, respectively) compared with users who were referred elsewhere (reduction of 15.47% [410/2650] and 3.21% [85/2650], respectively), and with users who were not shown the ads, who increased their behaviors (increase of 57.12% [6462/11,314] and 4.07% [461/11,314], respectively).  In addition, those referred to MyProAna increased their search for treatment, as did control users, who did so to a lesser extent.  However, users referred elsewhere decreased their searches for this content.


 We found that referring users interested in ED-related content to specific pro-ana communities might lessen their maladaptive online search behavior.  This suggests that those who are preoccupied with EDs can be redirected to less pathological online searches through appropriate pathways.


 TRIAL REGISTRATION
 ClinicalTrials.gov NCT03439553; https://clinicaltrials.gov/show/NCT03439553 (Archived by WebCite at http://www.webcitation.org/6xNYnxYlw).
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