Table 4.

Participant recruitment, engagement and retention in intervention studies using social media for smoking cessation

Study	Social media platform	Recruitment	Methods for promoting participant engagement	Participant engagement outcome	Methods for promoting participant retention	Participant retention outcome
Bakersville et al (2016)²⁵	Interactive website, social media campaign, and smartphone app	The Break-It-Off campaign was promoted through ads on Facebook, Google, Yahoo, and M icrosoft, and through television, radio, and print ads. Participants in the research study were recruited through the BIO website and ads on online classified services. The Smokers Helpline comparison group participants were recruited by phone. From January to M arch 2012 there were 44,172 total visits and 37,325 unique visitors to the BIO website. 342 registered for the study.	Participants received a $10 iTunes gift card for enrolling in the research study and a $15 iTunes gift card for completing the follow-up survey.	BIO campaign includes mobile app and integrated social media. Of the 37,325 visitors, 3937 downloaded the mobile app and 339 posted content on the social media components (Facebook and YouTube).	Participants received a $15 iTunes gift card for completing the follow-up survey.	102 (34%) of BIO participants and 136 (52%) of Smokers Helpline control group participants completed 3-month follow-up assessments.
Cheung et al (2015)²⁷	WhatsApp and Facebook	Recent quitters with mobile phones and Internet access were recruited through a smoking cessation clinical setting. 247 participants were screened, and 136 were enrolled in the study.	3 reminders sent each week by moderators to reinforce program content.	There were more posts in the WhatsApp groups (M =55.0; SD=50.7) compared to the Facebook groups (M =21.0; SD=34.4). Posts about sharing smoking or quitting experiences were most common in the WhatsApp (39%) and Facebook (66%) groups. The WhatsApp group may have been more effective at preventing relapse due to greater interaction among participants.	Participants were compensated approximately US $12.80 (HK $100) if they confirmed abstinence based on exhaled carbon monoxide and saliva sample. Participants were unaware of the incentive prior to follow-up.	At 2-months 37 (88%) WhatsApp, 38 (95%) Facebook, and 43 (80%) control group participants completed follow-up assessments. At 6-months 34 (81%) WhatsApp, 28 (70%) Facebook, and 38 (70%) control group participants completed follow-up assessments.
Cobb et al (2016)²⁸ Study protocol: Cobb et al (2014)³⁵	Facebook	Facebook advertising. 10% of eligible individuals were subsampled to complete a brief survey.	Users of the Facebook app receive alerts to check-in, prompts to confirm their quit date, or daily reminders to set a quit date. Game mechanics employed to promote engagement. Users can invite friends to the app.	Participants were more likely to view more content if they received prompts (p<0.001).	Participants were compensated $20 for each completed survey.	Subsample of 857 users surveyed; 407 (48%) completed follow-up surveys.
Haines-Saah et al (2015)²⁶	Facebook	Facebook advertising, Twitter page to promote the study, development of a brand identity to market study to youth, and combination of community recruitment efforts including flyers, posters, magnets, print ads in campus newspapers, referrals from participants, craigslist postings, and email lists. 134 inquiries about the study, required 10-months to enroll of 60 participants. 21/134 (16%) inquiries were referrals from friends participating in the study.	Participants received $10 each week for actively posting, commenting, or liking content. Weekly reminders to post content in the group were sent to participants via Facebook and email.	There were over 1,800 actions including photos, comments, likes, and shares. Participants posted a total of 283 photos.	Cumulative payment for engagement was provided to participants at the end of 12-week study period.	12 (20%) of participants dropped out of the study; 39 (65%) of participants completed follow-up survey.
Pechmann et al (2015)²⁹	Twitter	Participants were recruited using Google ads with a direct link to the Tweet2Quit website and study information and application form. Recruitment was completed with a $2000/month budget and required 4 months per group. 813 people completed the online form, 106 completed the screening survey, 45 were eligible, and 40 were enrolled.	Daily automated messages were used to encourage tweeting and discussion related to quitting smoking among participants. The messages encouraged participants to share their experiences (23%), list benefits (19%) or barriers (9%) to quitting, strategies for overcoming barriers to quitting (13%), provide emotional support to others for quitting (9%), set a quit date or use nicotine patches (6%), or express confidence about quitting (5%). Text messages and phone call reminders were used to improve response rates.	Participants posted a total of 2867 Tweets (average of 72 Tweets), and 31 (78%) of participants tweeted at least once. 653 (23%) Tweets were responses to auto messages, while 2214 (77%) Tweets were spontaneous. Daily Facebook use was correlated with greater engagement in the Tweet2Quit intervention.	Participants received a 56-day supply of nicotine patches for enrolling in the study.	Retention was 31 (78%) at 7 days, 31 (78%) at 30 days, and 28 (70%) at 60 days post quit date.
Pechmann et al (2016)³⁰ Secondary outcomes: Lakon et al (2016)³²	Twitter	Participants were recruited using Google ads with $10,000/month budget. The ads contained statements such as “Discover New Ways to Quit. Free patches and support through Twitter”. The ads linked to a study website with details about the study. 614 people completed the online form and were screened for eligibility, 444 did not meet inclusion criteria, 10 were excluded because enrolment closed, and 160 were enrolled and randomized.	Automated messages containing discussion topics were sent daily for 100 days. Participants also received individualized automated text messages sent to their phones to promote engagement in the intervention.	60 (75%) Tweet2Quit participants tweeted. In total there were 4,705 tweets with 58.8 tweets (SD=68.1) per participant. Participants tweeted for an average of 47.4 days (SD=38.9). Greater tweet volume predicted sustained abstinence. Responses to the daily automated messages accounted for 24% of all tweets.	Participants received a 56-day supply of nicotine patches for enrolling in the study.	65 (81%) Tweet2Quit participants and 70 (88%) control participants completed 60-day follow up. Tweet2Quit participants who tweeted were more likely to complete follow-up (88%; 53/60) compared to non-tweeters (60%; 12/20) (p=0.005).
Ramo et al (2015)³¹ Secondary outcomes: Ramo et al (2014)³³ and Thrul et al (2015)³⁴	Facebook	Facebook ads tailored by age, location and language, contained a link to an online screening survey or study Facebook page. 36 different types of ads including standard, newsfeed, promoted posts, and sponsored stories were delivered over 7 weeks. The ads generated 3,198,373 impressions, 5895 unique clicks. Images of smoking and newsfeed ads viewable on mobile phones were most effective. 586 (10%) people were study eligible and 230 (39%) consented at an average cost of $8.80 per participant.	Participants could be randomized to receive an additional $50 gift card for engaging in the intervention.	48 (61%) participants commented on at least one Facebook post; 40 (51%) liked at least one post; 28 (35%) participants reported reading most or all of the posts. The 21 (27%) most active participants accounted for 83% of all comments. Participants were more likely to comment on posts if they quit smoking (p=0.036) or received incentives (p=0.015).	Participants received $130 in gift cards for completing all assessments.	Of 230 consented participants, 79 (34.3%) completed baseline assessments. Of these, 65 (82%) completed 6 month assessments and 57 (72%) completed 12 month assessments.