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Abstract
Objective To review randomised controlled trials (RCTs) investigating the effectiveness of text message-based interventions for smoking cessation, including the effects of dose (number of text messages) and concomitant use of behavioural or pharmacological interventions.
Data sources We searched seven databases (PubMed, CINAHL, PsycINFO, Scopus, EMBASE, Cochrane Library and Web of Science), Google Scholar and the reference lists of relevant publications for RCTs. Eligible studies included participants aged ≥15 years who smoked tobacco at enrolment.
Study selection One reviewer screened titles and abstracts and two reviewers independently screened full texts of articles.
Data extraction One of three reviewers independently extracted data on study and intervention characteristics and smoking abstinence rates using Qualtrics software.
Data synthesis 30 of the 40 included studies reported higher rates of smoking cessation among those receiving text messaging interventions compared with comparators, but only 10 were statistically significant. A meta-analysis of seven RCTs found that participants receiving text messages were significantly more likely to quit smoking compared with participants in no/minimal intervention or ‘usual care’ conditions (risk ratio 1.87, 95% CI 1.52 to 2.29, p <0.001). Three trials found no benefit from a higher dose of text messages on smoking cessation. Two trials that tested the added benefit of text messaging to pharmacotherapy reported outcomes in favour of adding text messaging.
Conclusions Findings suggest that text messaging-based interventions are effective at promoting smoking cessation. Further research is required to establish if any additional benefit is gained from an increased number of text messages or concurrent pharmacotherapy or behavioural counselling.
- Cessation
- Global health
- Public policy
Data availability statement
Data are available upon request.
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Introduction
In recognition of the harmful effects of tobacco smoking,1–3 a variety of pharmacological4 and behavioural5 interventions have been developed to support smoking cessation. The ubiquity of mobile phones globally, the common use and cost-effectiveness of text messages, and the ability to provide tailored support at any time (eg, when experiencing stress or cravings) make text message-based interventions a feasible, low-cost and potentially effective option for promoting smoking cessation.6–8 Globally, there were an estimated 8.48 billion mobile phones in use in 2021, equal to 107 phones per 100 people.9 While mobile phone access is the greatest among high-income countries (124 subscriptions per 100 people), there is also increasingly good access among middle (110 per 100 people) and low-income countries (64 per 100 people).9 Hence, mobile text messaging interventions could provide impactful and cost-effective smoking cessation support in both low-resource and high-resource settings.
A 2019 Cochrane review of the effectiveness of text messaging and smartphone app-based interventions for smoking cessation found moderate-certainty evidence that automated text messaging interventions were more effective than minimal smoking cessation support (risk ratio (RR) 1.54, 95% CI 1.19 to 2.00; I2=71%; 13 studies, 14 133 participants).6 The authors also found that the addition of text messages encouraging smoking abstinence to other smoking cessation interventions was more effective at promoting smoking cessation than the other smoking cessation interventions alone (RR 1.59, 95% CI 1.09 to 2.33; I2=0%, 4 studies, 997 participants).6 With the literature searches for this Cochrane review conducted in 2018,6 it is timely to conduct an updated review. As such, this systematic review and meta-analysis of randomised controlled trials (RCTs) investigated the effectiveness of text messaging-based interventions for promoting tobacco smoking cessation. In particular, we examined the impacts of dose (ie, number of text messages) and concurrently delivered behavioural or pharmacological smoking cessation treatments on the effectiveness of text messaging interventions for increasing smoking cessation. This review was commissioned by the WHO to inform clinical guidelines for text messaging interventions for smoking cessation.
Methods
This systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines (checklist included in online supplemental material).10
Supplemental material
Review questions
How do text messaging-based interventions impact tobacco cessation outcomes compared with no or minimal intervention, placebo or usual/standard care?
What is the relationship between the number of text messages (ie, dose) and tobacco cessation outcomes?
How do text messaging-based interventions delivered in combination with behavioural or pharmacological smoking cessation interventions impact smoking cessation outcomes compared with use of text messages alone?
Search strategy
In June 2019, authors CP, CLS and EET conducted a systematic review of studies investigating the effectiveness of text messaging-based interventions for promoting tobacco smoking cessation published since 1 January 2010, with no limits on study design. The methods and search results for the 2019 review are included in online supplemental material (including the PRISMA diagram as online supplemental figure 1). Twenty-one studies were included in the review; of these, 15 were RCTs, and these 15 studies were retained for inclusion in the current study. To search for studies published since or missed in the 2019 review, the primary author (CP) searched seven databases (PubMed, CINAHL, PsycINFO, Scopus, EMBASE, Cochrane Library and Web of Science) on 14 February 2023 for articles published since June 2019 using search terms related to smoking cessation and text messaging (see online supplemental material for search terms). Next, to identify relevant articles not captured in database searches, author CP searched four trial registries (NIH Clinical Trials, Australian Clinical Trials, EU Clinical Trials Register and WHO International Clinical Trials Registry Platform), articles included in the 2019 Cochrane review on mobile phone text messaging and app-based interventions for smoking cessation,6 reference lists of relevant reviews excluded during article screening and of included articles, and conducted targeted searches of Google Scholar.
Inclusion/exclusion criteria
We included RCTs that described use of automated text messages to increase tobacco smoking cessation (text only, automated or interactive texts, delivered via the phone’s text messaging function or another similar app such as WhatsApp), either alone or in combination with pharmacological smoking cessation aids (eg, nicotine replacement therapy (NRT)) or other behavioural interventions (eg, counselling), among individuals (aged 15 years and over, based on the WHO’s defined age cut-off for adults as used for the Global Adult Tobacco Surveys11) who smoked tobacco on enrolment in the study, published in any language. We included studies that compared the text-messaging intervention with no intervention, a placebo, usual care or active treatments as comparators. Studies with active treatments as the comparators were only included if the comparators were behavioural interventions (eg, Quitline telephone counselling, individual or group counselling, printed materials), internet-based, artificial intelligence-based or smartphone-based interventions, or the following pharmacological interventions: NRT, bupropion or varenicline. We excluded studies where the text messaging interventions included pictures or videos sent via text, the only text message-based element of the study was text-based reminders about study participation, participant randomisation was by site or cluster (eg, by hospital) or where only outcomes less than 30 days from enrolment were reported.
Evidence selection
Figure 1 details the database search and retrieval process. After duplicates were removed in EndNote referencing software,12 each article’s title and abstract was independently screened against inclusion criteria by one reviewer (CP). The full texts of all articles not excluded at this stage were then independently screened by two reviewers (CP and IM). Conflicts were resolved through discussion with the senior author (CEG), who also checked all included articles to ensure they met inclusion criteria. All screening was conducted using Covidence web-based collaboration software.13
PRISMA diagram. PRISMA, Preferred Reporting Items for Systematic Reviews and Meta-Analyses.
Data extraction
Three reviewers (CP, IM and AH) independently extracted data from included articles using an online form created in Covidence software.13 Extracted data for each study included article author(s); publication year; funding source; aim; setting; recruitment method; population; inclusion criteria; exclusion criteria; design; type of analysis (intention to treat or per protocol); intervention(s); comparator(s); dose (ie, number of text messages) and duration of intervention; data collection dates; primary and secondary outcome measurement; method(s) of biochemical verification; sample size (total and in each group); participant characteristics (% male or female, mean age, mean cigarettes per day, mean Fagerström Test for Nicotine Dependence or Fagerström Test for Cigarette Dependence score); outcomes at all reported time points (both biochemically verified and self-reported; N and % abstinent; relative difference scores or RRs and p values); loss to follow-up rate; study funding, author conflicts of interest and authors’ conclusions. Where multiple outcome measures were available, we prioritised reporting continuous abstinence (preferably of 6 months or more) over point prevalence abstinence, biochemically validated results over self‐report and 6-month outcomes over other time points. Extracted data were reviewed by CP and CEG to ensure consistency and accuracy.
Risk of bias appraisal
We used Version 2 of the Cochrane risk-of-bias tool for randomised trials (RoB 2)14 to assess the risk of bias in included studies. The tool assesses bias across five domains: bias arising from the randomisation process; bias due to deviations from intended interventions; bias due to missing outcome data; bias in measurement of the outcome; and bias in selection of the reported result and provides an overall risk of bias score.14 For each domain, one of three judgement options is selected: low risk; some concerns or high risk. We used the RoB 2 Excel tool to appraise each article, and to create the traffic light figure.15
Adverse events
We have not included adverse events as a review outcome because there is no obvious risk of adverse events for text messaging-based interventions.
Meta-analysis
A random effects meta-analysis was conducted to estimate the effect of text messaging on smoking cessation for RCTs that were homogeneous enough to be combined and included an outcome of at least 6 months follow-up. Online supplemental table 1 provides reason(s) for exclusion for each study that was excluded from the meta-analysis of RCTs testing the effect of text messaging interventions compared with no/minimal intervention, placebo or usual care for smoking cessation. To test if the estimates were sensitive to inclusion of any single study, a leave-one-out analysis was conducted. To test the potential impact of publication bias, a trim-and-fill analysis was conducted. All analyses were conducted in R with the metafor package.
Certainty of evidence
Following Cochrane methodology,16 we used the five Grading of Recommendations Assessment, Development and Evaluation (GRADE) considerations (risk of bias, inconsistency, imprecision, indirectness and publication bias) to assess the certainty of the body of evidence for the abstinence outcome for each comparison, and to draw conclusions about the certainty of evidence within the text of the review.
Results
Search results
Fifteen studies were included in the 2019 search (see online supplementary material). Database searches in 2023 identified a further 16 relevant studies, and 9 additional eligible studies17–25 were identified from the Cochrane review of the effectiveness of text messaging and smartphone app-based interventions for smoking cessation (see figure 1).6 In total, 40 articles are included in this review.
Study characteristics
Online supplemental table 2–11 summarise each included study’s details and outcomes. There was wide variation in terms of comparator conditions; these included usual care21 25–29 NRT with or without other interventions,30–34 varenicline with or without other interventions,24 35 a brochure or other self-help materials,17 36–39 text messages with content unrelated to smoking cessation19 20 22 23 34 40–48 or lower frequency text messages encouraging smoking cessation (compared with higher frequency text messages),23 41 49 a smartphone app,50 individual or group counselling or mindfulness sessions,51 52 web-based programmes or resources,53–55 brief smoking cessation advice from a medical professional18 or emails encouraging smoking cessation.56 Studies were conducted in the USA,23 24 29–33 35 36 40 43 47 50 52 53 55 the UK,19–21 27 28 38 China,25 41 48 49 Hong Kong,17 34 45 Sweden,37 46 54 New Zealand,22 Spain,18 Türkiye,26 39 Norway,56 Vietnam,44 Brazil51 and Peru.42 Study populations included the general population,17 19 20 22 23 34 35 39 41 43 47 49 50 53 high school students (aged ≥16 years),37 54 young adults (aged 18–25 years),42 college and university students,46 people living with HIV,24 31 self-described racial/ethnic minority and socioeconomically disadvantaged individuals,29 32 52 pregnant people,27 38 40 people experiencing homelessness,30 33 fathers who smoked in the home,25 people attending emergency departments,36 hospital patients,18 51 smoking cessation clinic clients,26 45 registrants on a tobacco cessation website,55 56 community health centre patients,44 general practitioner patients21 and people with coronary heart disease.48
The intervention text messages often formed part of defined programmes such as Text2Quit,53 TXT-2-Quit,43 SmokefreeMOM,40 SmokefreeTXT,23 30 36 OnQ,50 NEXit,46 NEXit Junior,37 54 SMSalud,18 MiQuit,27 28 38 Txt2Stop,19 20 Happy Quit,49 iQuit,21 iQuit mindfully,52 BecomeAnEx29 and Stop My Smoking.47 In 12 studies, in addition to text messages, intervention and control group participants also received behavioural counselling (in-person counselling,21 25 26 30 31 33 35 43 45 52 or telephone counselling17 32), and in 12 studies, participants received pharmacological support (either NRT,30–34 36 50 52 varenicline,24 35 a ‘prescription for pharmacotherapy’21 or ‘bupropion or varenicline, as appropriate’45). In other studies, intervention group participants also received access to a website with information on smoking cessation (n=6 studies),29 38 47 53 55 56 written materials encouraging smoking cessation (n=6 studies),17 26–28 36 52 a Quitline referral,36 brief smoking cessation advice from a medical professional,18 the mobile number of another trial participant that they could text for support19 47 or referral to ‘smoking cessation services’ (no further detail provided).34 Outcomes were biochemically verified in 21 studies,17–20 25 27–29 31 32 35 38–40 44 45 47–49 52 53 while the remaining 19 studies relied solely on self-reported outcomes.21–24 26 30 33 34 36 37 41–43 46 50 51 54–56
How do text messaging-based interventions impact tobacco cessation outcomes compared with no intervention, placebo or usual/standard care?
Of the 40 included studies, 30 reported point estimates for the abstinence outcomes in favour of the text messaging intervention,18–29 32 33 36–40 42–47 49 50 53 54 56 compared with control group participants, but only 10 of these were statistically significant.18 19 21 23–26 46 49 53 Of the 10 studies that did not report outcomes in favour of the text-messaging intervention, 5 studies reported higher (but not significantly higher) quit rates among control group participants (compared with intervention group participants),17 31 35 48 51 and 5 studies reported no notable differences between groups.30 34 41 52 55 Table 1 shows these studies’ outcomes disaggregated by each study’s longest follow-up duration.
Included studies’ outcomes disaggregated by each study’s longest follow-up time point
Of the 10 studies reporting significantly higher smoking abstinence rates among intervention group participants, 4 studies’ interventions consisted of text messages only19 23 46 49; in the remaining 6 studies, text messages supplemented behavioural counselling21 24 26 (either 7 sessions of counselling combining cognitive–behavioural therapy (CBT) and motivational interviewing techniques,24 or 1 brief in-person session21 26), emails and access to a web portal,53 verbal and written information on the benefits of not smoking and healthy eating habits and in-person follow-ups with doctors and nurses who encouraged abstinence,18 or 1 week of varenicline followed by weekly supply until 12 weeks.24 In 6 of these 10 studies, participants could send a text (eg, the word ‘crave’) when experiencing a craving or a lapse to receive additional texts with specific tips.18 19 21 46 49 53 In three studies, text messages were tailored or personalised in some way,19 49 53 and three studies incorporated social cognitive theory in text message context.21 24 53 Comparators for these 10 studies consisted of referral to a web-based programme or resource,53 health advice from a health professional18 usual care, text messages unrelated to smoking cessation,19 23 46 lower frequency text messages49 or varenicline.24
Meta-analysis of text messaging intervention compared with placebo/no or minimal intervention/usual care
Seven studies comparing text messaging interventions to placebo/no intervention, minimal intervention or usual care with 5–6 months continuous abstinence outcomes were sufficiently similar to combine in a meta-analysis.18 19 21 22 26 49 54 The results showed that participants receiving text message interventions were significantly more likely to achieve 6 months continuous abstinence from smoking compared with participants in the control condition, RR 1.87, 95% CI (1.52 to 2.29), p<0.0001 (figure 2). Overall, there was no evidence of substantial between-study heterogeneity, Q(6)=8.9905, p=0.1741, I2=34.12%. A leave-one-out sensitivity analysis demonstrated that overall estimate was not very sensitive to excluding any study, with effect size ranges from 1.71 to 2.06. All results remained statistically significant (p<0.05). A test of funnel plot symmetry shows no significant evidence of asymmetry (p=0.6959; see online supplemental figure 2. The summary of outcomes for the meta-analysis is shown in table 2. More than half of the data for the meta-analysis (62.1%) came from studies with low risk of bias. The GRADE assessment found the evidence to be of high certainty.
Forest plot of three randomised controlled trials comparing higher and lower dose text messaging interventions for smoking cessation.
Summary of outcomes for text messaging-based interventions impact on tobacco cessation outcomes compared with minimal/no intervention, placebo or usual care (n=7 trials)
What is the relationship between the number of text messages (ie, dose) and tobacco cessation outcomes?
The number of text messages received by intervention group participants (ie, the ‘dose’ of the intervention) varied widely; this ranged from 8 texts sent across 7 days17 to 273 texts sent across 6 months22 with a median of 99 texts sent to each participant. The number of texts sent to participants was not clearly specified in 12 (30%) of the 40 included studies,21 28–30 32 33 36 38–40 43 47 limiting our ability to investigate the impact of text message dose on outcomes for these studies. Overall, there was no clear association between the number of text messages sent and cessation outcomes. Of the 10 studies that sent the most texts (range 13342 –27322 across the study period), 2 reported significantly higher abstinence rates among intervention group participants,19 46 4 reported a non-significant higher abstinence rate among intervention group participants,20 22 42 44 2 reported no clear differences between groups52 56 and 2 reported higher abstinence rates among control group participants.35 48 Of the five studies that sent the least texts (range 817–3051 texts across the study period), three reported higher abstinence rates among intervention group participants,17 23 45 with two of these significantly higher,17 23 one found no clear differences in outcomes between groups,34 and one found higher abstinence rates among control group participants.51
Three studies compared two different text messaging frequencies. One study tested a high-frequency text contact (HFTC) intervention versus a low-frequency text contact (LFTC) comparison group among 8000 participants in China.41 The HFTC group received up to an additional 91 texts over the 6 weeks (3 messages per day for weeks 1–2, 2 per day for weeks 3–5 and 1 per day for week 6) while the LFTC group received 1 text message each week, for a total of 6 texts. Participants in both conditions could elect to stop receiving text messages at any time. At 6 months, the 7-day point prevalence abstinence rate was identical between the two groups (27.7% intention-to-treat analysis), suggesting no benefit in the higher dose group. Furthermore, 42.9% of the HFTC group vs 15.4% of the LFTC group opted out of receiving further texts prior to the end of the 6-week intervention period (p<0.001).41 49 49 reported no additional benefit on 6-month outcomes of high-frequency text messaging (6.5%, 44/674 abstinent) over low-frequency text messaging (6%, 12/284 abstinent). Squiers et al tested 8 weeks of messages (2 weeks prequit and 6 weeks postquit) to 2 weeks of preparatory prequit date text messages and a control arm with smoking assessment and quit date reminders sent prequit date only, finding no additional benefit of the postquit text messages for 7-day point prevalence abstinence at 32 weeks follow-up (28.2%) compared with prequit preparation messages only (31.8%) or the control condition (29.6%).23Abroms et al 40 reported outcomes at 3 months in favour of a text messaging intervention (SmokefreeMOM) that delivered 3–6 messages a day to pregnant people (14.5%, 8/55 abstinent) against a single text with the Quitline number and printed quit materials (9.1%, 4/44 abstinent).
One study compared a tailored and a non-tailored text messaging programme.47 47 reported higher continuous abstinence outcome at 3 months in favour of text messages tailored to quitting stage with on demand text messages and additional resources and a discussion forum on a website (40%, 40/101 abstinent) compared with a similar text messaging programme that was not tailored to quit stage and did not have text on demand (30%, 19/63 abstinent), but the result was not statistically significant.
Meta-analysis of dose effects for text messaging interventions for smoking cessation (more text messages vs fewer)
We combined the three trials that tested two distinct doses of text messaging in terms of number of text messages sent in a random effects meta-analysis (see figure 3).23 41 49 Because there were insufficient studies with a continuous abstinence measure, we included 7-day point prevalence outcomes reported at a follow-up point at least 6 months from baseline. The results showed that participants receiving the higher dose text messaging interventions were not more likely to achieve abstinence at approximately 6-month follow-up compared with participants in the lower dose condition, RR 0.97, 95% CI 0.86 to 1.08. Overall, there was evidence of moderate between-study heterogeneity, Q(2)=5.0049, p=0.0803, I2=51.00%. There was no evidence of asymmetry in the funnel plot (p=0.2034; online supplemental figure 3). A leave-one-out sensitivity analysis demonstrated that the findings were not very sensitive to excluding any particular study, with effect size ranges from 0.95 to 1.11. All results remain statistically non-significant (p>0.05). The summary of outcomes for dose effects is presented in table 3. Our GRADE assessment judged the evidence for the pooled effect from the three trials to be of low certainty.
Forest plot of seven randomised controlled trials testing the effect of text messaging interventions compared with no/minimal intervention, placebo or usual care for smoking cessation.
Summary of outcomes for higher versus lower dose text messaging-based interventions’ impact on tobacco cessation outcomes compared with minimal/no intervention, placebo or usual care (n=3 trials)
How do text messaging-based interventions delivered in combination with behavioural or pharmacological smoking cessation interventions impact smoking cessation outcomes compared with use of text messages alone or the interventions without text messages?
Behavioural counselling
While participants received some form of behavioural counselling in 12 of the included studies,17 21 25 26 30–33 35 43 45 52 only 4 of these studies24 31 32 51 provided the counselling to either the intervention or control group participants, thus allowing for an investigation of the impact of the counselling on smoking outcomes. Two of the four studies were three-arm RCTs, where intervention group participants received telephone-based behavioural counselling in addition to text messages encouraging smoking cessation and pharmacotherapy (either varenicline24 or NRT32), and the two comparison groups received either pharmacotherapy alone or pharmacotherapy plus text messages encouraging smoking cessation.24 32 First, in a three-arm RCT,24 participants received either (1) varenicline; (2) varenicline and text messages or (3) varenicline, text messages and seven sessions of phone-delivered adherence-focused motivational and behavioural therapy. At the 12-week follow-up, participants in the third group had the highest abstinence rates (15.7%) compared with those who received varenicline alone (5.7%,) or varenicline and text messages (3.7 %), suggesting that the behavioural counselling sessions improved cessation rates, but text messaging alone did not. The study’s authors noted that the addition of the counselling was associated with significantly improved cessation rates even after controlling for varenicline adherence, suggesting that counselling may have increased motivation to quit and remain abstinent.24 Second, in a similar three-arm RCT, participants received either (1) NRT; (2) NRT and text messages or (3) NRT, text messages and 11 sessions of proactive telephone counselling.32 As with the previous study, the third arm had the highest rates of biochemically verified abstinence (25.5%) compared with abstinence rates of 12.0% for each of the other arms at 6 months follow-up. These findings further suggest that text messages alone do not improve cessation outcomes compared with pharmacotherapy alone, but the addition of behavioural counselling increases effectiveness. As neither trial included a medicine with counselling arm only, it is unknown if the text messages enhanced the counselling effect.
In a third study, control group participants received telephone-based behavioural counselling, while intervention group participants received text messages only.51 Higher (but not significantly higher) abstinence rates were observed among participants receiving telephone counselling sessions than those who only received text messages encouraging cessation. However, the authors noted that the text messaging intervention was half as expensive as telephone counselling.51 In the fourth study, control group participants received one standard care counselling session, while intervention group participants received one tailored session of CBT in addition to text messages.31 There was no significant difference in quit rates between groups, but those who received CBT reported a significantly greater reduction in cigarettes per day.31 These studies further suggest improved smoking cessation outcomes when adding behavioural counselling to text messaging interventions promoting smoking cessation.
Pharmacological support
Of the 12 studies where participants received some form of pharmacological support,21 24 30–36 45 50 52 5 provided the pharmacotherapy to either intervention or control participants,24 26 36 45 50 while the remaining 7 provided identical pharmacotherapy to both groups. Of these, two reported positive findings for the text messaging intervention; one trial reported outcomes in favour of text messaging over a smartphone app (non-significant difference),50 and the other reported significantly higher quit rates among intervention participants who received a tailored advice report and tailored text messages compared with usual care (including pharmacotherapy).26 A trial that compared counsellor-delivered counselling via WhatsApp compared with a standard text messaging intervention among participants offered treatment with NRT, bupropion or varenicline reported outcomes in favour of the WhatsApp intervention, but the difference was not significant.45 In a US-based study among people living with HIV, participants who received text messages and varenicline reported significantly higher rates of smoking abstinence than those who received varenicline alone.24 Finally, one study reported a non-significant outcome in favour of a multicomponent intervention (4-week supply of nicotine patches and gum, a referral to the Quitline, and text messaging, and a brochure on the state Quitline) compared with the control condition that only received the brochure (9/30 abstinent at 3 months vs 4/30).36
Risk of bias appraisal
Our judgements on the risk of bias of included studies using the RoB2 are summarised in figure 4. We rated eight studies as being at low risk of bias, 10 as having some concerns, and 22 as being at high risk of bias. The majority of studies rated as being at high risk of bias were rated as such due to non-reporting of key study details, including the extent of blinding, which analyses (if any) were used to estimate the effective assignment to the intervention, whether measurement of the outcome differed between intervention groups, or whether assessment of the outcome was influenced by knowledge of the intervention received.
Risk of bias summary: review authors’ judgements about each risk of bias item for each included study.
Of the 22 studies rated as being at high risk of bias, 7 reported significantly higher rates of abstinence among intervention group participants,21 23–25 46 49 53 12 reported a non-significant higher abstinence rate among intervention group participants,20 22 28 29 33 36 37 39 40 44 47 50 1 reported no differences between groups52 and 2 reported a non-significant higher abstinence rate among control group participants.31 35
Discussion and conclusions
Forty studies were included in this systematic review investigating the effectiveness of text messaging interventions for promoting smoking cessation. Of these, 30 reported outcomes in favour of the text messaging intervention compared with the comparator condition,17–29 32 33 36–40 42–47 49 50 53 54 with 10 of these reporting a statistically significant effect.18 19 21 23–26 46 49 53 Our meta-analysis found that participants receiving text messages promoting smoking cessation were significantly more likely to achieve 6 months’ continuous abstinence from smoking compared with participants in a control condition. There was high certainty evidence that participants who received text messaging interventions (compared with no or minimal intervention, placebo or ‘usual care’) were significantly more likely to achieve 6 months’ sustained abstinence compared with participants in the control condition. With this review’s findings supporting the effectiveness of text message-based interventions for smoking cessation, and considering the low cost of sending text messages51 and the global ubiquity of mobile phones,6–8 there is clear merit in promoting the use of text message-based interventions for individuals attempting to quit smoking.
These findings strengthen the conclusions of previous reviews reporting that text messaging-based interventions are effective for promoting smoking cessation.6 57 58 A previous Cochrane review found only moderate-certainty evidence for text messaging interventions compared with minimal support and a pooled RR of 1.54 (95% CI 1.19 to 2.00) with a meta-analysis of 13 studies.6 There were some differences in the studies we included compared with the 2019 Cochrane review. First, we only included RCTs that included participants who currently smoked at baseline (trials that included people who did not smoke tobacco or had recently quit were excluded), that randomised on the individual level (cluster trials were excluded), and investigated interventions that were simple text-based messaging interventions (interventions involving video or images were excluded). We also restricted the meta-analysis to those trials that reported at least 5 months’ sustained abstinence at follow-up of 6 months or longer since baseline, and excluded trials with unclear duration of abstinence. We also identified two additional trials that met our criteria that were published since the Cochrane review was undertaken.26 54
We did not find any relationship between the intervention dose (ie, number of texts received by participants) and smoking cessation outcomes. However, the number of texts sent to participants was not clearly specified in 12 (30%) of the 40 included studies, precluding a thorough investigation of the impact of varying the intervention dose. We recommend that future studies clearly provide this information, to ensure that the impact of intervention dose can be accurately measured through stratified analyses. To facilitate this, we recommend more widespread use of the template for intervention description and replication (TIDieR) checklist, an extension of the Consolidated Standards of Reporting Trials (CONSORT) and Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) statements developed to improve the completeness of the reporting of interventions.59 Furthermore, more studies designed specifically to examine the impact of text message ‘dose’ (frequency, duration and timing of text messages) would be valuable. It was also interesting that higher dose groups had a higher opt-out rate for the programme in one study,41 demonstrating that there is potentially an optimal dose level that provides a trade-off between consumer retention and dose-dependent smoking cessation outcome.
SPIRIT statements developed to improve the completeness of the reporting of interventions.59 Furthermore, more studies designed specifically to examine the impact of text message ‘dose’ (frequency, duration and timing of text messages) would be valuable. It was also interesting that higher dose groups had a higher opt-out rate for the programme in one study,41 demonstrating that there is potentially an optimal dose level that provides a trade-off between consumer retention and dose-dependent smoking cessation outcome.
We were similarly limited in our ability to understand the impact of concurrent behavioural or pharmacological interventions. Only two studies24 32 measured the impact of concomitant behavioural counselling and text messages compared with text messages alone, and either varenicline24 or NRT.32 Both found significantly higher rates of smoking abstinence among participants who received both text messages and behavioural counselling versus pharmacotherapy and text messages or pharmacotherapy alone,24 32 however, neither included an arm with pharmacotherapy and behavioural counselling without text messages. Similarly, only one study measured the impact of receiving NRT in addition to text messages encouraging cessation; the authors found higher (but not significantly higher) rates of abstinence among intervention group participants (vs control group participants who only received a brochure on the health benefits of quitting smoking) at 3 months post-treatment.36 Further trials are needed to establish the impact of text messaging interventions delivered in combination with behavioural and/or pharmacological smoking cessation interventions versus text messages alone or pharmacotherapy and behavioural counselling alone to provide clearer evidence to inform clinical practice. While the benefit of adding text messaging to pharmacotherapy or behavioural counselling is uncertain, it is unlikely to adversely impact cessation outcomes.
Limitations
Our findings are subject to some limitations. First, while our review benefited from a comprehensive literature search, it is possible that we missed relevant publications. We only included published findings and excluded those only reported in conference abstracts. Due to wide heterogeneity in study designs and comparators, only seven trials were included in our meta-analysis. Several of the studies were rated as high risk of bias using the ROB2 tool due to missing information, but not necessarily due to elements of the study design that increased risk of bias in the studies’ findings. A leave-one-out sensitivity analysis indicated the findings were not sensitive to the inclusion of these studies.
Conclusion
This systematic review and meta-analysis found high certainty evidence that text messaging interventions can be effective for promoting smoking cessation compared with no or minimal intervention. However, there was no evidence of greater effectiveness with more intensive text messaging compared with less intensive messaging. Most trials that tested a text messaging intervention as an adjunct to pharmacotherapy did not report an additional benefit from the text messaging.
Other information
Registration and protocol
A study protocol was not registered due to an oversight in handover during project coordinator staffing changes but is available in online supplemental material.
Data availability statement
Data are available upon request.
Ethics statements
Patient consent for publication
Acknowledgments
We would like to acknowledge Dr Hebe Gouda and Dr Dongbo Fu from the WHO for advice on the protocol, and Matthys Ungerer and Georgina Chelberg for their assistance with literature searches and data extraction for a previous iteration of this project.
References
Supplementary materials
Supplementary Data
This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.
Footnotes
Twitter @ChenealPuljevic, @kyliemorphett, @CoralGartner
Contributors Study conception and design: CEG, CP, KM, DS, GC, CLS and EET. Article screening: CP and IM. Data extraction: CP, IM, AH, DS and EG. Data analysis: HK, GC and CEG. Draft manuscript preparation: CP, CEG, IM, AH, DS, CLS, EET, KM, HK, GC and CEG. Guarantor: CP. All authors reviewed and approved the final version of the manuscript.
Funding Funding for this study was provided by the WHO. Funders provided advice on the protocol but played no role in data extraction or interpretation. CP is supported by a Discovery Early Career Researcher Award from the Australian Research Council (DE230101131). CEG is supported by the National Health and Medical Research Council Centre of Research Excellence on Achieving the Tobacco Endgame (NHMRC Grant GNT1198301) and an Australian Research Council Future Fellowship (FT220100186).
Competing interests None declared.
Provenance and peer review Not commissioned; externally peer reviewed.
Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.