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Review the literature about smoking cessation, Internet based interventions, etc  2.1 Overview  This chapter provides background information about previous research which suggests that Internet-and Cell phone-based interventions have the potential to achieve short –term cessation of smoking and it includes a description of each of these studies. Furthermore it provides information about risk factors for smoking among adolescents and adults, benefits of Smoking Cessation and Internet- and Cell phone-based interventions, the search of the literature and information about this Meta-Analysis.  2.2 Smoking among adolescents and adults  2.2.1 Risk factors for smoking among adolescents and adults  Smoking often starts in adolescence. ‘In abstinence of intervention, adolescent smokers will most likely become adult smokers’ (USDHHS, 2014).  There are many risk factors for cigarette smoking among adolescents and adults. Joffer et al. (2014) indicated that smoking most often starts sometime during adolescence and continuous through to adulthood if no intervention was successful or was sought. Findings from this research suggested that peers, friends, siblings, tobacco advertisement and especially interpersonal and psychological factors inclusive of stress and low self-esteem were significant influences in smoking initiation among adolescents.   Furthermore, Navas-Nacher (2015) suggested that exposure to cigarette smoking during childhood years was a significant risk factor for the reason that it was learned behaviour. This research found that exposure to household smoking behaviour also referred to as ‘living with a regular smoker who smoked in the home’ nearly doubled the risk of becoming a smoker compared to those who had never been exposed to household smoking. 40% of participants who reported that they had been exposed to smoking in the home they lived in during their childhood and adolescence years and 20% of them were current smokers.  Inter-personal and psychological factors inclusive of stress and low self-esteem including already identified nicotine addiction were significant factors among adult smokers (Joffer, 2014). This research also indicated that people smoke for a variety of reasons related to family and social pressures, risk seeking, stress reductions and more. They may pass through stages of smoking from trying a cigarette to addiction and they suffer nicotine withdrawal with abrupt decrease from cigarettes along the way (Joffer, 2014).  2.3 Smoking Cessation  2.3.1 Quitting Measures  Velicer et al. (1997, cited in Velicer, 2004) classified outcomes of smoking cessation studies into three measures a) point prevalence abstinence refers to the percent of people not smoking at any given point in time, b) continuous abstinence refers to the percent of people not smoking at all since the onset of the intervention and c) prolonged abstinence refers to the percent of people abstinent for some interval. The most minimum time intervals for point prevalence abstinence are 24 hours, 7-days and 30-days and the advantages of point prevalence abstinence is that non-smoking may be biochemically validated. It includes people who have progressed through the stages of change and it includes people who delay action and quit at a later time after an intervention. However point prevalence may overestimate the number of quitters because people may start smoking again at a later time and smokers who quit within the common point prevalence time frames of 24 hours, one week or one month may only experience the immediate health benefits of cessation. Continuous abstinence is more stable over time because for longer periods of abstinence also the likelihood of relapse reduces and it allows for the evaluation of longer-term health effects of smoking cessation. However continuous abstinence includes only a small number of smokers who quit without relapses also this only decreases as more quitters relapse and it cannot be validated biochemically. Prolonged abstinence refers to that smokers have been abstinent for a long time period inclusive of 6-12 months. This is more stable than point prevalence, it allows smokers who take delayed action to quit to be counted and it can assess long-term health benefits, however this requires a long follow up period and cannot be validated biochemically (Velicer, 2004).  West (2009) proposed The Russell Standard, which defines the smoking status in clinical research for monitoring the throughout success rates of stop smoking services, allowing meaningful direct comparisons between the services. The Russell Standard outlines six criteria including a) A ‘treated smoker (TS)’ is a smoker who undergoes at least one treatment session on or prior to the quit date. Smokers who attended an assessment session but fail to attend thereafter will not be counted. Neither are smokers who have already stopped smoking at the time they first came to the attention of the services; b) A smoker is counted as a ‘self-reported 4-week quitter (SR4WQ)’ if he/she is a ‘treated smoker’, is assessed (face-to-face, by postal questionnaire or by telephone) 4 weeks after the designated quit date (minus 3 days or plus 14 days) and declares that he/she has not smoked even a single puff on a cigarette in the past 2 weeks, c) A smoker is counted as a ‘Co-verified 4-week quitter (4WQ) if he/she is a ‘self-reported 4-week quitter’ and his/her expired –air CO is assessed 4 weeks after the designated quit date (minus 3 days or plus 14 days) and found to be less than 10ppm; d) A smoker is counted as ‘lost to follow up at 4 weeks (LFU4W)’ if on attempting to determine the 4 –week quitter status, he/she cannot be contacted; e) A smoker is counted as a ’52-weeks quitter (52WQ)’ if he/ she is a ‘treated smoker’, is assessed (Face-to face, by postal questionnaire or telephone) 52 weeks after the designated quit date (plus or minus 30days) and declares that he/she has not smoked more than five cigarettes in the past 50 weeks, f) A ‘treated smoker’ is counted as a ‘lost to follow up at 52 weeks (LFU52W)’ if on attempting to determine the 52-week quitter status, he/she cannot be contacted.  2.3.2 Trans-theoretical Model of Behaviour Change (TTM)  Prochaska and DiClemente (1983) developed the Trans-theoretical Model of Behaviour Change which describes the progression through which smokers go through before terminating their addiction. This model of behaviour change divides itself into the stages of change, processes of change and levels of change and it identifies five stages of readiness for changing a health behaviour including smoking behaviour among smokers: 1) pre-contemplation, 2) contemplation, 3) preparation, 4) action and 5) maintenance (Prochaska & DiClemente, 1983). Pre-contemplation is described as the stage in which smokers are not thinking about quitting or intending to quit in the next 6 months. The reason for this may be people may not be informed about the consequences of smoking and demoralized in their ability to make the behaviour change. They may be resistant or unmotivated for behavioural change (Prochaska & DiClemente, 1983). The next stage is the contemplation stage, in which individuals are considering quitting within the next 6 months and people in this stage are more aware of the benefits of quitting. Furthermore, the preparation stage includes smokers who are intending on quitting smoking within the next 30 days. These smokers may have taken action in the past by reducing smoking or making a quit attempt and they also have a plan for action (Prochaska & Velicer, 1997). The action stage is the stage in which smokers have quit during the past 6 months and the maintenance stage consists of people who have quit for more than 6 months. This model also recognizes that people move through the stages in a spiral pattern in which some people progress through and relapse while others progress and successfully quit. (Velicer et al, 2004).  2.3.3 Internet- and Cell phone components included in smoking cessation programmes  More health care providers are now including Internet and Cell phone components inclusive of text messaging, emails, accessing websites, accessing video clips online, access to online discussion forums and information within their smoking cessation programmes. The Internet and Cell phone allows people to receive information and treatment at any time, wherever they are and it provides anonymity.   2.4 Internet- and Cell phone-based interventions in smoking cessation  The Internet and Cell phone have become increasingly useful in the delivery of health care including smoking cessation programmes world-wide and within New Zealand. Internet- and Cell phone-based interventions are described as interventions in which the Internet and Cell phone are a main part of the smoking cessation programme. These mentioned interventions are inclusive of but not limited to access to websites containing information about dangers of smoking, quitting, prevention of relapse, questionnaires, online discussion forums, access to private chat messages and online peer support, online smoking cessation diary, , informative and motivational emails and text messages including advice and suggestions about strategies how to cope with craving situations, interactive voice response and video clips containing information about smoking and presentations from medical professionals.  Previous research suggests that Internet- and Cell phone-based interventions have the potential to achieve cessation of smoking among adult smokers, however results are short term and it is uncertain whether these above mentioned interventions can help achieve longer-term cessation of smoking. Internet- and Cell phone-based interventions are inclusive of access to websites containing information about the dangers of smoking, quitting, relapse prevention, questionnaires, online discussion forums, access to private chat messages and online peer support, online smoking cessation diary, informative and motivational emails and text messages including advice and suggestions about strategies how to cope with cravings situations and interactive voice response.  Internet only  Etter et al. (2005) assessed two computer-tailored interventions for smoking cessation. ‘Stop-Tabac’ is a French language website inclusive of fact sheets, online booklets, answers to frequently asked questions, access to personal stories written by current and former smokers, games, forums and chat room; and 11969 participants aged 18 years plus took part in this. Findings of this research suggest personalized messages via emails can be effective short-term and 25.2% versus 15.7% had quit smoking at the 2.5 months follow up. Participants were asked to complete a 62-item questionnaire providing the following information: their smoking history, their smoking status, the stage of change they are in, if they had quit before, their level of tobacco dependence, their attitudes towards smoking and their coping methods. Participants received personalized counselling in form of a letter, illustrated with cartoons and graphs specific to match their match their answers from the questionnaire. The other programme used a shorter 38-item questionnaire however their counselling letter was based on information about Nicotine replacement (NRT) and with not much information about health risks of smoking and how to deal with craving situations.  Schwartz et al. (2006) assessed short-term efficacy (90 days) of an automated behavioural intervention for smoking cessation which was delivered via an Internet website. 351 participants were included and the majority of them (86%) were aged between 26 and 55 years. It was expected that participants quit within the next 30 days. Results from this research indicate that web-based interventions can have a positive impact on changing health behaviours. 24.1% presented abstinence at 90 days post quit date. The 1-2-3 Smoke free programme included a website which was designed to be an automated approximation of the experience a smoker would receive when working with a live smoking cessation counsellor. This intervention was inclusive of five major content modules: benefits of stopping smoking, overcoming common barriers to cessation, strategies for avoiding situations that prompt cravings, strategies for dealing with cravings and setting a quit date. The last included creating a personalized quit plan calendar with individual advice and a list of options for social support. The intervention included video segments which included a physician presenting a message about the health importance of stopping smoking. There was no personal email or telephone component included therefore participants only interacted with the website. The control group received nothing for 90 days.  Strecher et al. (2005) assessed the efficacy of a web-based computer-tailored smoking cessation programme as a supplement to nicotine patch therapy. Results demonstrate effectiveness of web-based interventions in conjunction with Nicotine Replacement Therapy. 29% of the web & Nicotine Group had quit compared to 23.9% in the web-only group at 6 weeks. At 12 weeks 28% of the web and Nicotine Replacement Group compared to 18% in web-only group. This included 3971 participants aged 18 years plus and who used NiQuitin (CQ) 21mg patch. The following interventions were compared: the active CQ plan and a non-tailored web-based smoking cessation programme. Participants were asked to complete a questionnaire and provide the following information: demographics, their smoking history, their motives for quitting, their expectations about more challenging situations during the quit process. Based on information included in the questionnaires, participants received three tailored newsletters delivered via email and behavioural support messages also delivered via email over a period of 10 weeks. Emails included a cessation guide inclusive of suggestions about how to stay quit and overcoming craving situations and were also encouraging compliance with Nicotine Replacement Therapy (NRT) since all participants were using NiQuitin (CQ). Additionally participants were allowed to identify a supportive person that would receive an email with advice how to support the participant. The control group received the newsletters and emails including advice and no Nicotine Replacement Therapy (NRT).   Cell phone only  Bramley et al. (2005) assessed the effectiveness of using mobile phone text messaging interventions among Maori and non-Maori to achieve cessation of smoking. Findings suggest short-term effectiveness of Cell phone-based intervention self-reported abstinence rates. 26% of intervention group compared with 11.2% of the control group reported abstinence at 6 weeks. 1705 participants (Maori and non-Maori) aged 16 years plus were included in this study. The STOMP- Stop Smoking by Mobile Phone intervention included regular, personalized text –messages providing smoking cessation advice, support and distraction. Participants self-identifying as Maori received in addition to text messages in English also text-messages in Maori. There were 140 texts specifically developed. Five text messages daily for 4 weeks were sent after participant’s quit day. 6 weeks after quit date text-messages were reduced from five text messages daily to three text messages per week until follow up at 26 weeks. The control group received no smoking-related information and only received one text message a fortnight. There were no differences found between Maori and non-Maori.  Research conducted by Obermeyer et al. (2004) assessed Cell phone components in smoking cessation programmes among college students. Findings from this study present 28% had quit and 43% had made at least one 24 hour quit attempt. 46 college students aged between 18-25 years participated in this study. The interventions were inclusive of text messages and access to a website. Firstly a questionnaire including the following information: participant’s smoking habit and smoking pattern, basic history of their smoking, information about their high-risk cravings situations, their motivation and self-efficacy to quit was completed by participants. Participants had access to a website using a log-in and were encouraged to visit the website daily. The programme also offered text-messages inclusive of motivational messages and several educational components on topics including information on how to handle withdrawal symptoms of smoking, information how to handle high-risk situations sent using a Cell phone. Participants were able to alert everyone by sending a ‘SOS-messages’ (in urge for help messages) at the time they found themselves in a high-risk situation in which they craved a cigarette. This intervention also offered peer-support, allowed selected others inclusive of family and close friends of participants to follow the smokers’ progress on the website and send additional text messages encouraging the smoker in their quitting.   Research done by Ybarra et al. (2012) assessed cessation rates in a text-messaging based smoking cessation programme. 45% of the intervention group and 36% of the control group reported abstinence at 12 weeks and this result was confirmed by carbon monoxide testing (CO). 151 Participants were included in this study and they were aged 18 years plus. This programme was based on motivational and supportive text-messages. Participants were asked to answer the following questions: to describe their feelings about smoking how they would rate their craving for a cigarette on a scale from 1-3, if they wanted to quit, the reasons why they wanted to quit and what they would do if someone offered them a cigarette. A informative brochure including understanding quitting, strategies on how to cope with craving situations and how to stay committed to quitting and information about smoking behaviour and dangers, finding out their smoking patterns and the reason why they smoke, learn how to start up a smoking diary, advice on how to involve their family and friends in supporting them but also learn to become a self-supporter was provided to all participants including the ones in the control group. The intervention group received text messages in addition to the informative brochure. Five text messages inclusive motivational and supportive advice was sent out to participants on a daily base. Abstinence was measured using self-reported as well as carbon monoxide (CO) testing  Internet & Cell phone  Research done by Riley et al. (2008) assessed Internet- and cell phone-based interventions among college students. At 6 weeks 45% achieved abstinence (self-reported) and 42% were based on cotinine verification. These results indicate that Internet- and Cell phone-based interventions are potentially efficacious and an easily disseminated method for providing cessation interventions to young adult smokers. This study included 31 college students aged between 18 and 24 years. The web-based component of this intervention provided the participants with educational modules including information about smoking and smoking dangers, progress-monitoring tools including quit calendar and email alerts to user-selected significant others who would provide social support at critical times during the programme. Text messages were personalised and on the basis of participants individual quit date. Participants received between one and three text messages daily. These included personal advice about how to stay quit, strategies how to cope with craving situations and how to stay abstinent. Most participants received two text messages daily. Additionally participants could sent an ‘emergency message’ when the needed additional support.   2.5 Search Results of Literature  112 articles were retrieved from the main database search and five articles were retrieved from other database searches. After duplicates were removed, the title and abstract of 92 articles was studied and four articles were gained and discovered using the reference research method. Full text was obtained of 25 articles and seven articles were obtained from a previous search of the literature. The seven articles which were obtained from a previous search of the literature were used to demonstrate evidence of previous research conducted in smoking cessation. After all fourteen studies met the inclusion criteria after their full texts have been assessed and were further investigated in this Meta-Analysis.  2.6 Meta-Analysis  2.6.1. The Role of this Meta-Analysis  A Meta-Analysis was conducted to investigate the role of Internet-and Cell phone-based interventions ‘delivered via email, accessing websites, text messages’ to achieve longer-term cessation of smoking among adult smokers. A Meta-Analysis is referred to as a statistical combination of results from two or more primary studies (Cochrane, 2008). A Meta-Analysis refers to a method that uses statistical techniques to combine results from different studies to obtain a quantitative estimate of the overall effect of a particular intervention on a defined outcome. It is a statistical process for pooling data from many clinical trials to gain a clear conclusion (Medical Dictionary, 2015).   There are several advantages in conducting a Meta-Analysis. These include achieving an increase in power as power is referred to as the chance of detecting a real effect of statistical significance if it exists, to improve accuracy known as the estimation of intervention effect which can be improved if it is based on more information, to assist in answering questions which are not presented by individual primary studies due to them involving a specific type of participants and specifically defined interventions, this way a selection of studies in which these specific characteristics differ can allow investigation of the consistency of effect and reasons for the difference in effect estimates, to settle controversies arising from apparently conflicting studies and to generate new hypotheses. For this reason this statistical analysis of findings allows the degree of conflict to be formally assessed and reasons for different results to be explored and quantified.  2.6.2 Randomized controlled trials included in this Meta-Analysis  Fourteen studies met the inclusion criteria after their full texts have been assessed.  Three of them inclusive of Borland (2013), Brendryen (2008) and Brendryen (2008) assessed both Internet- and Cell phone-based interventions. Six of them inclusive of Elfeddali (2012), Haug (2011), McKay (2008), Seidman (2010), Wangberg (2011) and Zbikowski (2011) evaluated Internet-based interventions. Additionally five studies inclusive of Free (2009), Free (2011), Haug (2013), Rodgers (2005) and Skov-Ettrup (2014) investigated Cell phone-based interventions. Furthermore (Brendryen 2008) included Nicotine Replacement Therapy and Zbikowski (2011) included additional telephone calls.  Description of included studies  Borland et al. (2013) assessed Internet- and Cell phone-based interventions in smoking cessation programmes. The main outcome of this research was self-reported abstinence at 6 months. Participants included in this study were 3530 adults (2195 in the intervention group and 1335 in the control group) aged 18 years plus, owned a Cell phone and had access to the Internet. Quit Coach is a personalized smoking cessation programme delivered over the Internet and Cell phone. These interventions included letters of advice, suggestions about strategies on how to cope with cravings and motivational messages. The control group received brief information on web-and phone-based interventions.  Research conducted by Brendryen (2008) assessed Internet-and Cell phone interventions. The outcome studied was self-reported abstinence at 6 and 12 months. Participants were 396 adults (197 in the intervention group and 199 in the control group) 18 years plus, who had daily access to the Internet and owned a Cell phone. Happy Ending is a one year smoking cessation programme delivered via the Internet and Cell phone. It consists of emails, access to webpages, interactive voice response, text messages, access to a craving helpline, strategies on how to cope with cravings situations. All participants were given free Nicotine Replacement Therapy (NRT). The control group received self-help booklets including 44 pages containing general information, a quit diary and telephone numbers from the National Quitline.  Brendryen (2008) assessed Internet and Cell phone interventions and the outcome studied was self-reported abstinence at 6 and 12 months. 290 adults (144 in the intervention group and 146 in the control group) 18 years plus, who owned a Cell phone and had access to the Internet were included. Participants did not receive any Nicotine Replacement Therapy. The intervention included emails, access to webpages and text messages including strategies on how to stay abstinent. The Control group had access to general resources including books and magazines about self-treatment.  Elfeddali (2012) assessed Internet-based interventions in smoking cessation programmes. The outcomes studied were self-reported and biochemically verified abstinence at 12 months. Participants were 2031 adults (1395 in the intervention group and 636 in the control group) aged 18 years plus. Stay quit for you study (SQ4U) includes online assignments and questionnaires, including information about dangers of smoking, the benefits of not smoking and motivational messages. The Control group only filled out questionnaires and did not receive emails and interventions.  Free (2009) assessed Cell phone-based interventions and the outcome studied was self-reported and biochemically verified abstinence at 6 months. Participants were 200 adolescents and adults (102 in the intervention group and 98 in the control group) aged 16 years plus, who owned a Cell phone. STOMP- Stop Smoking with Mobile Phone is a six months cessation programme delivered via Cell phone. Participants received regular personal text messaging with advice and support to help distract from cravings and withdrawal symptoms. Five to six messages per day were sent for 4 weeks and the maintenance stage included one message every fortnight. Quit Buddy and messages on demand were available. The Control group received one text per fortnight.  Free (2011) assessed Cell phone-based interventions and the outcome was 6 months self-reported and biochemically verified abstinence at 6 months. This research included 5800 adolescents and adults (2915 in the intervention group and 2885 in the control group) aged 16 years plus and who owned a Cell phone. This six months smoking cessation programme was delivered via Cell phone. Participants received five text messages for the first 3 weeks, then three per week for 26 weeks. A total of 156 messages were sent and messages included motivational and support messages to help participants stay abstinent. They could text ’lapse’ to receive urgent advice and to receive peer support. The control group received simple short text messages on a fortnightly basis. Self-reported and biochemically verified abstinence was assessed using postal salivary cotinine testing and carbon monoxide testing in person.  Haug (2011) assessed Internet-based interventions and the outcome was self-reported abstinence at 6 months. Participants included in this research were 477 adults (242 in the intervention group and 235 in the control group) aged 18 years plus, who had access to emails and the Internet.  Haug (2013) assessed Cell phone-based interventions and the outcome was self-reported abstinence at 6 months. Participants included were 755 adults (372 in the intervention group and 383 in the control group) aged 18 years plus and who owned a Cell phone. SMS Quit Coach is a smoking cessation programme that includes text messages at least three times per week, motivational messages, two text messages per week for 3 months and messages including information on strategies how to cope with withdrawal symptoms. The control group received no text messages.  McKay (2008) assessed Internet-based interventions and the outcome was self-reported abstinence at 6 months. Participants included were 2318 adults (1159 in the intervention group and 1159 in the control group) aged 18 years plus and who had access to the Internet. QSN (Quit Smoking Network) users were directed through websites and the programme provided strategies on how to stay non-smoking, how to overcome cravings and a web-forum was provided. The control group received online resources (factsheets) articles.  Rodgers (2005) assessed Cell phone-based interventions and 1705 adolescents and adults (852 in the intervention group and 853 in the control group) aged 18 years plus took part in this. This six months smoking cessation programme delivered via Cell phone included regular personalized text messages with information and advice to help distract participants from cravings for a cigarette. Messages on demand were available. The control group received one text message per fortnight.  Seidman (2010) assessed the effectiveness of internet interventions and the outcome was self-reported abstinence at 6 months and 13 months. 2153 Adults (1106 in the intervention group and 1047 in the control group) aged 18 years plus and who had access to the Internet. Participants were provided with a link to access an interactive website for information and to complete a series of exercises to help reinforce the motivation to quit and stay abstinent. Emails included advice and strategies how to cope with triggers for a cigarette. The control group had access to a non- interactive website containing downloadable self-help booklets (designed by American Cancer Society).  Skov-Ettrup (2014) assessed Cell phone interventions and the outcome was self-reported abstinence at 12 months. 2030 adolescents and adults (1055 in the intervention group and 975 in the control group) aged 15 years plus who owned a cell phone were included. Xhalke.dk is a smoking cessation program which includes Internet- and Cell phone components. Two personalized daily text messages including advice on how to cope with specific situations were delivered to participants. The control group received weekly text messages.  Wangberg (2011) assessed Internet based interventions and the outcome studied was self-reported abstinence at 12 months. Included were 2298 adolescents and adults (1171 in the intervention group and 1127 in the control group) aged 16 years plus. This smoking cessation programme based on general advice included dangers of smoking, motivational messages, discussion forum and a personalized online cessation diary was delivered for 12 months. Buddy support and private chat messages were available. The control group received also an Internet-based intervention but had no email contact.  Zbikowski (2011) assessed the Internet and included additional telephone calls. The outcome studied was self-reported abstinence at 6 months. 1198 adults (797 in the intervention group and 401 in the control group) aged 18 years plus were included. The website included interactive tools, a discussion forum, personalized emails, five one-on one telephone calls for 7 days and 21 days while the control group only received telephone calls but no access to the website.  Participants  Nine studies Borland (2013), Brendryen (2008), Brendryen (2008*), Elfeddali (2012), Haug (2011), Haug (2013), McKay (2008), Seidman (2010) and Zbikowski (2011) included participants aged 18 years plus, three studies Free (2009), Free (2011) and Wangberg (2011) included adolescents aged 16 years plus and two studies Rodgers (2005) and Skov-Ettrup (2014) included participants aged 15 years plus. Sample sizes among the studies ranged from 200 participants (Free 2009) to 5800 participants (Free 2011).   Interventions  Borland (2013), Brendryen (2008) and Brendryen (2008) assessed both Internet- and Cell phone-based interventions whereas Free (2009), Free (2011), Haug (2013), Rodgers (2005) and Skov-Ettrup (2014) included Cell phone-based interventions. Elfeddali (2012), Haug (2011), McKay (2008), Seidman (2010), Wangberg (2011) and Zbikowski (2011) assessed Internet-based interventions. Brendryen (2008) used Nicotine Replacement Therapy additionally and Zbikowski (2011) additional telephone calls.  Outcomes  All fourteen studies inclusive of Borland (2013), Brendryen (2008), Brendryen (2008*), Elfeddali (2012), Free (2011), Free (2009), Haug (2013), Haug (2011), McKay (2008), Rodgers (2005), Seidman (2010), Skov-Ettrup (2014), Wangberg (2011) and Zbikowski (2011) reported abstinence of smoking for at least six months or more after the start of the intervention. For all these studies a seven-day point prevalence self-reported abstinence of smoking was the main outcome. Two of these studies reported a 30-day point prevalence additionally. Elfeddali (2012), Free (2011) and Free (2009) assessed self-reported abstinence and used biochemical verification testing to measure abstinence.  Recruitment  Recruitment was very similar among the studies. Borland (2013), Brendryen (2008), Brendryen (2008), Skov-Ettrup (2014) and Zbikowski (2011) recruited their participants through quit websites and advertisements in online newspapers. Rodgers (2005), Skov-Ettrup (2014) and Zbikowski (2011) got their participants from quitline and cancer societies. Free (2011), Free (2009) used the radio, leaflets and posters for their recruitment. Rogers (2005) put posters up at tertiary institutions within the region. Haug (2013) and Haug (2011) recruited their participants from a rehabilitation centre and Zbikowki (2011) found their participants through referrals from General Practitioners.  An overall Analysis inclusive of a Fixed-effect and a Random-effect Analysis of all fourteen studies was conducted. Previously was decided that if heterogeneity was found among studies, individual subgroup analyses would be conducted to further investigate these results. The details of this are described in the Methods section.