Incentives for breastfeeding and for smoking cessation in pregnancy: An exploration of types and meanings

How and why do financial incentives contribute to helping people stop smoking? A realist review

BACKGROUND

Tobacco smoking remains a key cause of preventable illness and death globally. In response, many countries provide extensive services to help people to stop smoking by offering a variety of effective behavioural and pharmacological therapies. However, many people who wish to stop smoking do not have access to or use stop smoking supports, and new modes of support, including the use of financial incentives, are needed to address this issue. A realist review of published international literature was undertaken to understand how, why, for whom, and in which circumstances financial incentives contribute to success in stopping smoking for general population groups and among pregnant women.

METHODS

Systematic searches were undertaken from inception to February 2022 of five academic databases: MEDLINE (ovid), Embase.com, CIHAHL, Scopus and PsycINFO. Study selection was inclusive of all study designs. Twenty-two studies were included. Using Pawson and Tilley's iterative realist review approach, data collected were screened, selected, coded, analysed, and synthesised into a set of explanatory theoretical findings.

RESULTS

Data were synthesised into six Context-Mechanism-Outcome Configurations and one overarching programme theory after iterative rounds of analysis, team discussion, and expert panel feedback. Our programme theory shows that financial incentives are particularly useful to help people stop smoking if they have a financial need, are pregnant or recently post-partum, have a high threshold for behaviour change, and/or respond well to external rewards. The incentives work through a number of mechanisms including the role their direct monetary value can play in a person's life and through a process of reinforcement where they can help build confidence and self-esteem.

CONCLUSION

This is the first realist review to synthesise how, why, and for whom financial incentives work among those attempting to stop smoking, adding to the existing evidence demonstrating their efficacy. The findings will support the implementation of current knowledge into effective programmes which can enhance the impact of stop smoking care.

PROSPERO REGISTRATION NUMBER

CRD42022298941.

Understanding for whom, under what conditions and how smoking cessation services for pregnant women in the United Kingdom work-a rapid realist review

BACKGROUND

Maternal smoking in pregnancy is associated with several adverse maternal and infant health outcomes including increased risk of miscarriage, stillbirth, low birth weight, preterm birth, and asthma. Progress to reduce rates of smoking at time of delivery in England have been slow and over the last decade, less than half of pregnant women who accessed services went onto report having quit. This realist review was undertaken to improve the understanding of how smoking cessation services in pregnancy work and to understand the heterogeneity of outcomes observed.

METHODS

The initial programme theory was developed using the National Centre for Smoking Cession and Training Standard Treatment Programme for Pregnant Women and the National Institute for Health and Care Excellence guidance on treating tobacco dependency. A search strategy and inclusion criteria were developed. Four databases were searched to identify published papers and four websites were hand searched to identify any unpublished literature that could contribute to theory building. Realist logic was applied to the analysis of papers to identify the contexts in which the intended behaviour change mechanism(s) were triggered, or not, and towards what outcomes to develop context mechanism outcome configurations.

RESULTS

The review included 33 papers. The analysis produced 19 context mechanism outcome configurations structured under five closely interconnected domains (i) articulating harm, (ii) promoting support, (iii) managing cravings, (iv) maintaining commitment and (v) building self-efficacy. This review identifies two key processes involved in how services achieve their effects: how material resources are implemented and relationships. Of the two key processes identified, more existing literature was available evidencing how material resources are implemented. However, the review provides some evidence that non-judgemental and supportive relationships with healthcare workers where regular contact is provided can play an important role in interrupting the social cues and social practice of smoking, even where those around women continue to smoke.

CONCLUSIONS

This review clarifies the range of interconnected and bi-directional relationships between services and the personal and social factors in women's lives. It underscores the importance of aligning efforts across the models five domains to strengthen services' ability to achieve smoking cessation.

New Directions for Motivational Incentive Interventions for Smoking Cessation

Background

Motivational incentive interventions are highly effective for smoking cessation. Yet, these interventions are not widely available to people who want to quit smoking, in part, due to barriers such as administrative burden, concern about the use of extrinsic reinforcement (i.e., incentives) to improve cessation outcomes, suboptimal intervention engagement, individual burden, and up-front costs.

Purpose

Technological advancements can mitigate some of these barriers. For example, mobile abstinence monitoring and digital, automated incentive delivery have the potential to lower the clinic burden associated with monitoring abstinence and administering incentives while also reducing the frequency of clinic visits. However, to fully realize the potential of digital technologies to deliver motivational incentives it is critical to develop strategies to mitigate longstanding concerns that reliance on extrinsic monetary reinforcement may hamper internal motivation for cessation, improve individual engagement with the intervention, and address scalability limitations due to the up-front cost of monetary incentives. Herein, we describe the state of digitally-delivered motivational incentives. We then build on existing principles for creating just-in-time adaptive interventions to highlight new directions in leveraging digital technology to improve the effectiveness and scalability of motivational incentive interventions.

Conclusions

Technological advancement in abstinence monitoring coupled with digital delivery of reinforcers has made the use of motivational incentives for smoking cessation increasingly feasible. We propose future directions for a new era of motivational incentive interventions that leverage technology to integrate monetary and non-monetary incentives in a way that addresses the changing needs of individuals as they unfold in real-time.

Breastfeeding, Personal Responsibility and Financial Incentives

Should financial incentives be offered to mothers for breastfeeding? Given the significant socioeconomic and sociodemographic differences in breastfeeding in the USA, researchers and policymakers are exploring the role of financial incentives for breastfeeding promotion with the objective of increasing uptake and reducing disparities. Despite positive outcomes in other health domains, the acceptability of financial incentives is mixed. Financial incentives in the context of infant feeding are particularly controversial given the complex obligations that characterize decisions to breastfeed. After situating the specific ethical tensions related to personal responsibility, fairness, and intrusiveness, we argue that exploring carefully designed financial incentives can be ethically justified to support breastfeeding uptake particularly given (i) established medical guidelines that support breastfeeding benefits, (ii) wide socioeconomic and racial/ethnic disparities and (iii) notable influences in the broader choice architecture of infant feeding in the USA. Additional empirical research is warranted to better understand effectiveness, cost and specific ethical concerns related to free and informed choice.

Incentives for Smoking Cessation During Pregnancy: An Ethical Framework

Introduction

Smoking during pregnancy increases the risk of morbidity and mortality of the mother and child. The inability of the unborn child to protect itself, raises the social and academic responsibility to protect the child from the harmful effects of smoking. Interventions including rewards (incentives) for lifestyle changes are an upcoming trend and can encourage women to quit smoking. However, these incentives can, as we will argue, also have negative consequences, for example the restriction of personal autonomy and encouragement of smoking to become eligible for participation. To prevent these negative consequences, we developed an ethical framework that enables to assess and address unwanted consequences of incentive-based interventions whereby moral permissibility can be evaluated.

Aims and Methods

The possible adverse consequences of incentives were identified through an extensive literature search. Subsequently, we developed ethical criteria to identify these consequences based on the biomedical ethical principles of Beauchamp and Childress.

Results

Our framework consists of 12 criteria. These criteria concern (1) effectiveness, (2) support of a healthy lifestyle, (3) motivational for the target population, (4) stimulating unhealthy behavior, (5) negative attitudes, (6) personal autonomy, (7) intrinsic motivation, (8) privacy, (9) fairness, (10) allocation of incentives, (11) cost-effectiveness, and (12) health inequity. Based on these criteria, the moral permissibility of potential interventions can be evaluated.

Conclusions

Incentives for smoking cessation are a response to the responsibility to protect the unborn child. But these interventions might have possible adverse effects. This ethical framework aims to identify and address ethical pitfalls in order to avoid these adverse effects.

Implications

Although various interventions to promote smoking cessation during pregnancy exist, many women still smoke during pregnancy. Interventions using incentives for smoking cessation during pregnancy are a promising and upcoming trend but can have unwanted consequences. This ethical framework helps to identify and address ethical pitfalls in order to avoid these adverse effects.

It can be a practical tool in the development and evaluation of these interventions and in evaluating the moral permissibility of interventions using incentives for smoking cessation during pregnancy.

Planning, implementation and evaluation of antenatal weight management programmes: What are the key components? A mixed methods study

OBJECTIVE

To provide an understanding of the influential components required for the planning, delivery and evaluation of antenatal weight management programmes for women who are overweight or obese.

DESIGN

Two phase sequential explanatory mixed methods design comprising of an online survey and one-to-one telephone interviews.

SETTING AND PARTICIPANTS

All UK maternity services (n = 168) and local government councils (n = 417).

FINDINGS

From the 378 responses, 49 maternity services and 28 local government councils reported having an antenatal weight management programme. Of the 62 responses that specified BMI as an inclusion criterion only two-fifths (40.3% n = 25) adhered to the recommended threshold to include women with a BMI ≥30 kg/m². Although having a multi-disciplinary team was identified as fundamental when planning a programme, only 20.6% (n = 14/68) of the programmes involved service users during the planning phase. How the programme was communicated to a woman was a key factor which determined whether she partook in the programme or not. Having administrative support and staff with expertise in data collection were essential when evaluating a programme. Staff having protected time was identified as important when planning, delivering and evaluating a programme. Three overarching themes were identified from the individual interviews (n = 14) 'choices and decisions', 'demands and resources' and 'engagement and disengagement'.

KEY CONCLUSIONS

National guidelines recommendations regarding service user involvement when planning programmes and the BMI threshold used for inclusion are not being met. In addition to having adequate time, personnel and finances, successful programmes are dependent on the confidence and communication skills of midwives to raise the issue of obesity with these women at the booking appointment. Without staff having the time and necessary knowledge and skills, evaluation, and hence demonstrating programme impact, will likely remain difficult. Organisational support is needed to release resources to plan, deliver and evaluate these programmes. Strategic communication strategies are needed to promote the programme to both women and staff within organisations. Future programmes need to ensure there is engagement with service users from the planning of the programme through to evaluation.

Acceptability of financial incentives for health-related behavior change: An updated systematic review

Despite the successes of financial incentives in increasing uptake of evidence-based interventions, acceptability is polarized. Given widespread interest in the use of financial incentives, we update findings from Giles and colleagues' 2015 systematic review (n = 81). The objectives of this systematic review are to identify what is known about financial incentives directed to patients for health-related behavior change, assess how acceptability varies, and address which aspects and features of financial incentives are potentially acceptable and not acceptable, and why. PRISMA guidelines were used for searching peer-reviewed journals across 10 electronic databases. We included empirical and non-empirical papers published between 1/1/14 and 6/1/18. After removal of duplicates, abstract screening, and full-text reviews, 47 papers (n = 31 empirical, n = 16 scholarly) met inclusion criteria. We assessed empirical papers for risk of bias and conducted a content analysis of extracted data to synthesize key findings. Five themes related to acceptability emerged from the data: fairness, messaging, character, liberty, and tradeoffs. The wide range of stakeholders generally preferred rewards over penalties, vouchers over cash, smaller values over large, and certain rewards over lotteries. Deposits were viewed unfavorably. Findings were mixed on acceptability of targeting specific populations. Breastfeeding, medication adherence, smoking cessation, and vaccination presented as more complicated incentive targets than physical activity, weight loss, and self-management. As researchers, clinicians, and policymakers explore the use of financial incentives for challenging health behaviors, additional research is needed to understand how acceptability influences uptake and ultimately health outcomes.

Incentives for smoking cessation

BACKGROUND

Financial incentives, monetary or vouchers, are widely used in an attempt to precipitate, reinforce and sustain behaviour change, including smoking cessation. They have been used in workplaces, in clinics and hospitals, and within community programmes.

OBJECTIVES

To determine the long-term effect of incentives and contingency management programmes for smoking cessation.

SEARCH METHODS

For this update, we searched the Cochrane Tobacco Addiction Group Specialised Register, clinicaltrials.gov, and the International Clinical Trials Registry Platform (ICTRP). The most recent searches were conducted in July 2018.

SELECTION CRITERIA

We considered only randomised controlled trials, allocating individuals, workplaces, groups within workplaces, or communities to smoking cessation incentive schemes or control conditions. We included studies in a mixed-population setting (e.g. community, work-, clinic- or institution-based), and also studies in pregnant smokers.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. The primary outcome measure in the mixed-population studies was abstinence from smoking at longest follow-up (at least six months from the start of the intervention). In the trials of pregnant women we used abstinence measured at the longest follow-up, and at least to the end of the pregnancy. Where available, we pooled outcome data using a Mantel-Haenzel random-effects model, with results reported as risk ratios (RRs) and 95% confidence intervals (CIs), using adjusted estimates for cluster-randomised trials. We analysed studies carried out in mixed populations separately from those carried out in pregnant populations.

MAIN RESULTS

Thirty-three mixed-population studies met our inclusion criteria, covering more than 21,600 participants; 16 of these are new to this version of the review. Studies were set in varying locations, including community settings, clinics or health centres, workplaces, and outpatient drug clinics. We judged eight studies to be at low risk of bias, and 10 to be at high risk of bias, with the rest at unclear risk. Twenty-four of the trials were run in the USA, two in Thailand and one in the Phillipines. The rest were European. Incentives offered included cash payments or vouchers for goods and groceries, offered directly or collected and redeemable online. The pooled RR for quitting with incentives at longest follow-up (six months or more) compared with controls was 1.49 (95% CI 1.28 to 1.73; 31 RCTs, adjusted N = 20,097; I² = 33%). Results were not sensitive to the exclusion of six studies where an incentive for cessation was offered at long-term follow up (result excluding those studies: RR 1.40, 95% CI 1.16 to 1.69; 25 RCTs; adjusted N = 17,058; I² = 36%), suggesting the impact of incentives continues for at least some time after incentives cease.Although not always clearly reported, the total financial amount of incentives varied considerably between trials, from zero (self-deposits), to a range of between USD 45 and USD 1185. There was no clear direction of effect between trials offering low or high total value of incentives, nor those encouraging redeemable self-deposits.We included 10 studies of 2571 pregnant women. We judged two studies to be at low risk of bias, one at high risk of bias, and seven at unclear risk. When pooled, the nine trials with usable data (eight conducted in the USA and one in the UK), delivered an RR at longest follow-up (up to 24 weeks post-partum) of 2.38 (95% CI 1.54 to 3.69; N = 2273; I² = 41%), in favour of incentives.

AUTHORS' CONCLUSIONS

Overall there is high-certainty evidence that incentives improve smoking cessation rates at long-term follow-up in mixed population studies. The effectiveness of incentives appears to be sustained even when the last follow-up occurs after the withdrawal of incentives. There is also moderate-certainty evidence, limited by some concerns about risks of bias, that incentive schemes conducted among pregnant smokers improve smoking cessation rates, both at the end of pregnancy and post-partum. Current and future research might explore more precisely differences between trials offering low or high cash incentives and self-incentives (deposits), within a variety of smoking populations.

Women's views about a free breast pump service: Online survey informing intervention development

Improving breastfeeding outcomes is a global priority; however, in the United Kingdom, continuation of breastfeeding remains low. Growing empirical evidence suggests a free breast pump service might be an acceptable and feasible incentive intervention to improve breastfeeding outcomes and reduce heath inequalities. To inform intervention development, we conducted an online survey with women recruited via social media using snowball sampling. Data were analysed descriptively (closed questions) with qualitative thematic analysis (free text). The survey was completed by 666 women, most of whom had recently breastfed and used a breast pump. Participants agreed that free pump hire (rental/loan; 567 women; 85.1%) or a free pump to keep (408; 61.3%) should be provided. Free text comments provided by 408 women (free pump) and 309 women (free hire) highlighted potential benefits: helping women to continue breastfeeding; express milk; overcome difficulties; and pump choice. Concerns are possible effect on breast milk supply, reduced breastfeeding, pumps replacing good support for breastfeeding, and pump hire hygiene. Personal and societal costs are important issues. Some suggested a pump service should be for low-income mothers, those with feeding difficulties or sick/preterm infants. A one-size service would not suit all and vouchers were proposed. Some suggested fees and deposits to prevent waste. To our knowledge, this is the first study reporting views about the acceptability of providing a free breast pump hire service. Mothers support and wish to have a say in breast pump service development. Future evaluations should address impact on feeding outcomes, professional support, hygiene for hired pumps, and costs.

Commercial versus technical cues to position a new product: Do hedonic and functional/healthy packages differ?

Packaging attributes can be classified into two main blocks: visual/commercial attributes and informational/technical ones. In this framework, our objectives are: (i) to compare if both kinds of attributes lead to equal responses (consumers' attitudes improvement and product trial) and (ii) to compare if they work equally when a hedonic or a healthy new product is launched into the young market. An experimental design was defined to reach both objectives. Two packaging attributes were manipulated orthogonally to introduce greater variation in people's perceptions: a visual cue (the color) and an informative cue (the claim/label). A third variable was introduced: hedonic (candy bars) versus functional/healthy products (juice with fruit and milk). In a laboratory, 300 young consumers chose and evaluated one of the different packages that were simulated (using different colors and labels). Our results show that both kinds of attributes are significant, but visual cues were more strongly associated with young consumers' positive attitudes towards the product and their intention to buy than technical cues. Results do not differ between the product categories.7.

Design of effective interventions for smoking cessation through financial and non-financial incentives

Smoking has a tremendous negative impact on the Canadian economy and contributes to growing costs in the healthcare system. Efforts to reduce smoking rates may therefore reduce strain on the healthcare system and free up scarce resources. Academic literature on economic smoking cessation incentives presents a countless variety of interventions that have met with varying degrees of success. This study reviews six different variables used in the design of incentives in smoking cessation interventions: direction, form, magnitude, certainty, recipient grouping, and target demographic. The purpose of this study is to provide analysis and recommendations about the contribution of each variable into the overall effectiveness of smoking cessation programs and help health leaders design better interventions according to their specific needs.

Effect of prenatal smoking cessation interventions on birth weight: meta-analysis

BACKGROUND

Smoking is preventable factor for pregnancy outcomes such as low birth weight (LBW). In this study, we assessed the effects of smoking cessation in pregnancy period on the birth weight in Randomized Controlled Trial studies (RCTs).

METHODS

International databases of Pub Med, Scopus, and Web of Science, by the MeSH heading and/or additional terms, were searched to assess relevant studies in systematic possess. I² statistics was used to assess of heterogeneity. Pooled effects size was obtained by random effects model. Meta-regression was used to explore of heterogeneity using Stata software version 12 (Stata Corp, College Station, TX).

RESULTS

A total 16 RCTs, 6192 women were enrolled to assess of smoking cessation in pregnancy period on the birth weight. Relative risk (RR) of not smoking at the end of pregnancy in intervention group was 2.47 (95% CI: 1.73-3.20). The odds ratio (OR) for effect of smoking cessation on LBW was 0.65 (95% CI: 0.42-0.88) and standardized mean difference (SMD) was significantly increased in the intervention group, 0.28 (95% CI: 0.05-0.50).

CONCLUSIONS

Results of this study approve results of previous RCTs that smoking cessation in pregnancy is a good practical action to prevention of LBW in infants.

Acceptability of financial incentives for health behaviour change to public health policymakers: a qualitative study

Background

Providing financial incentives contingent on healthy behaviours is one way to encourage healthy behaviours. However, there remains substantial concerns with the acceptability of health promoting financial incentives (HPFI). Previous research has studied acceptability of HPFI to the public, recipients and practitioners. We are not aware of any previous work that has focused particularly on the views of public health policymakers.

Our aim was to explore the views of public health policymakers on whether or not HPFI are acceptable; and what, if anything, could be done to maximise acceptability of HPFI.

Methods

We recruited 21 local, regional and national policymakers working in England via gatekeepers and snowballing. We conducted semi-structured in-depth interviews with participants exploring experiences of, and attitudes towards, HPFI. We analysed data using the Framework approach.

Results

Public health policymakers working in England acknowledged that HPFI could be a useful behaviour change tool, but were not overwhelmingly supportive of them. In particular, they raised concerns about effectiveness and cost-effectiveness, potential ‘gaming’, and whether or not HPFI address the underlying causes of unhealthy behaviours. Shopping voucher rewards, of smaller value, targeted at deprived groups were particularly acceptable to policymakers. Participants were particularly concerned about the response of other stakeholders to HPFI – including the public, potential recipients, politicians and the media.

Overall, the interviews reflected three tensions. Firstly, a tension between wanting to trust individuals and promote responsibility; and distrust around the potential for ‘gaming the system’. Secondly, a tension between participants’ own views about HPFI; and their concerns about the possible views of other stakeholders. Thirdly, a tension between participants’ personal distaste of HPFI; and their professional view that they could be a valuable behaviour change tool.

Conclusions

There are aspects of design that influence acceptability of financial incentive interventions to public health policymakers. However, it is not clear that even interventions designed to maximise acceptability would be acceptable enough to be recommended for implementation. Further work may be required to help policymakers understand the potential responses of other stakeholder groups to financial incentive interventions.

Perspectives on financial incentives to health service providers for increasing breast feeding and smoking quit rates during pregnancy: a mixed methods study

OBJECTIVE

To explore the acceptability, mechanisms and consequences of provider incentives for smoking cessation and breast feeding as part of the Benefits of Incentives for Breastfeeding and Smoking cessation in pregnancy (BIBS) study.

DESIGN

Cross-sectional survey and qualitative interviews.

SETTING

Scotland and North West England.

PARTICIPANTS

Early years professionals: 497 survey respondents included 156 doctors; 197 health visitors/maternity staff; 144 other health staff. Qualitative interviews or focus groups were conducted with 68 pregnant/postnatal women/family members; 32 service providers; 22 experts/decision-makers; 63 conference attendees.

METHODS

Early years professionals were surveyed via email about the acceptability of payments to local health services for reaching smoking cessation in pregnancy and breastfeeding targets. Agreement was measured on a 5-point scale using multivariable ordered logit models. A framework approach was used to analyse free-text survey responses and qualitative data.

RESULTS

Health professional net agreement for provider incentives for smoking cessation targets was 52.9% (263/497); net disagreement was 28.6% (142/497). Health visitors/maternity staff were more likely than doctors to agree: OR 2.35 (95% CI 1.51 to 3.64; p<0.001). Net agreement for provider incentives for breastfeeding targets was 44.1% (219/497) and net disagreement was 38.6% (192/497). Agreement was more likely for women (compared with men): OR 1.81 (1.09 to 3.00; p=0.023) and health visitors/maternity staff (compared with doctors): OR 2.54 (95% CI 1.65 to 3.91; p<0.001). Key emergent themes were 'moral tensions around acceptability', 'need for incentives', 'goals', 'collective or divisive action' and 'monitoring and proof'. While provider incentives can focus action and resources, tensions around the impact on relationships raised concerns. Pressure, burden of proof, gaming, box-ticking bureaucracies and health inequalities were counterbalances to potential benefits.

CONCLUSIONS

Provider incentives are favoured by non-medical staff. Solutions which increase trust and collaboration towards shared goals, without negatively impacting on relationships or increasing bureaucracy are required.

The Impact of the 2009 Special Supplemental Nutrition Program for Women, Infants, and Children Food Package Revisions on Participants: A Systematic Review

For the first time since 1980, the US Department of Agriculture Food and Nutrition Service Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) food package policies were revised in 2009 to meet the Institute of Medicine's nutrition recommendations. These changes included increases in fruits, vegetables, whole grains, and low-fat dairy to improve nutrition and health of WIC participants. Our systematic review of the literature assessed the influence that the 2009 WIC food package revisions have had on dietary intake, healthy food and beverage availability, and breastfeeding participation. The systematic review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses recommendations. Four electronic databases were searched between April 1 and 30, 2014, for peer-reviewed research. Two reviewers screened the articles, extracted the data, and established inter-rater reliability by discussing and resolving discrepancies. Twenty articles were included that met our inclusion criteria. Nine of the studies analyzed changes in dietary intake, eight examined changes in healthy food and beverage availability, and three evaluated breastfeeding participation exclusively. The review demonstrated an improved dietary intake and an increase in the availability of healthier foods and beverages in authorized WIC stores. The revised food package was also associated with improved dietary intake of WIC participants. Mixed results were demonstrated in regard to improved breastfeeding outcomes. Further research is needed to assess the influence of WIC 2009 food package revisions on breastfeeding outcomes and to make conclusions about broad nutrition-related implications.

Incentives for smoking cessation

BACKGROUND

Material or financial incentives are widely used in an attempt to precipitate or reinforce behaviour change, including smoking cessation. They operate in workplaces, in clinics and hospitals, and to a lesser extent within community programmes. In this third update of our review we now include trials conducted in pregnant women, to reflect the increasing activity and resources now targeting this high-risk group of smokers.

OBJECTIVES

To determine whether incentives and contingency management programmes lead to higher long-term quit rates.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group Specialised Register, with additional searches of MEDLINE, EMBASE, CINAHL and PsycINFO. The most recent searches were in December 2014, although we also include two trials published in 2015.

SELECTION CRITERIA

We considered randomised controlled trials, allocating individuals, workplaces, groups within workplaces, or communities to experimental or control conditions. We also considered controlled studies with baseline and post-intervention measures. We include studies in a mixed-population setting (e.g. community-, work-, institution-based), and also, for this update, trials in pregnant smokers.

DATA COLLECTION AND ANALYSIS

One author (KC) extracted data and a second (JH-B) checked them. We contacted study authors for additional data where necessary. The main outcome measure in the mixed-population studies was abstinence from smoking at longest follow-up, and at least six months from the start of the intervention. In the trials of pregnant smokers abstinence was measured at the longest follow-up, and at least to the end of the pregnancy.

MAIN RESULTS

Twenty-one mixed-population studies met our inclusion criteria, covering more than 8400 participants. Ten studies were set in clinics or health centres, one in Thai villages served by community health workers, two in academic institutions, and the rest in worksites. All but six of the trials were run in the USA. The incentives included lottery tickets or prize draws, cash payments, vouchers for goods and groceries, and in six trials the recovery of money deposited by those taking part. The odds ratio (OR) for quitting with incentives at longest follow-up (six months or more) compared with controls was 1.42 (95% confidence interval (CI) 1.19 to 1.69; 17 trials, [20 comparisons], 7715 participants). Only three studies demonstrated significantly higher quit rates for the incentives group than for the control group at or beyond the six-month assessment: One five-arm USA trial compared rewards- and deposit-based interventions at individual and group level, with incentives available up to USD 800 per quitter, and demonstrated a quit rate in the rewards groups of 8.1% at 12 months, compared with 4.7% in the deposits groups. A direct comparison between the rewards-based and the deposit-based groups found a benefit for the rewards arms, with an OR at 12 months of 1.76 (95% CI 1.22 to 2.53; 2070 participants). Although more people in this trial accepted the rewards programmes than the deposit programmes, the proportion of quitters in each group favoured the deposit-refund programme. Another USA study rewarded both participation and quitting up to USD 750, and achieved sustained quit rates of 9.4% in the incentives group compared with 3.6% for the controls. A deposit-refund trial in Thailand also achieved significantly higher quit rates in the intervention group (44.2%) compared with the control group (18.8%), but uptake was relatively low, at 10.5%. In the remaining trials, there was no clear evidence that participants who committed their own money to the programme did better than those who did not, or that contingent rewards enhanced success rates over fixed payment schedules. We rated the overall quality of the older studies as low, but with later trials (post-2000) more likely to meet current standards of methodology and reporting.Eight of nine trials with usable data in pregnant smokers (seven conducted in the USA and one in the UK) delivered an adjusted OR at longest follow-up (up to 24 weeks post-partum) of 3.60 (95% CI 2.39 to 5.43; 1295 participants, moderate-quality studies) in favour of incentives. Three of the trials demonstrated a clear benefit for contingent rewards; one delivered monthly vouchers to confirmed quitters and to their designated 'significant other supporter', achieving a quit rate in the intervention group of 21.4% at two months post-partum, compared with 5.9% among the controls. Another trial offered a scaled programme of rewards for the percentage of smoking reduction achieved over the course of the 12-week intervention, and achieved an intervention quit rate of 31% at six weeks post-partum, compared with no quitters in the control group. The largest (UK-based) trial provided intervention quitters with up to GBP 400-worth of vouchers, and achieved a quit rate of 15.4% at longest follow-up, compared to the control quit rate of 4%. Four trials confirmed that payments made to reward a successful quit attempt (i.e. contingent), compared to fixed payments for attending the antenatal appointment (non-contingent), resulted in higher quit rates. Front-loading of rewards to counteract early withdrawal symptoms made little difference to quit rates.

AUTHORS' CONCLUSIONS

Incentives appear to boost cessation rates while they are in place. The two trials recruiting from work sites that achieved sustained success rates beyond the reward schedule concentrated their resources into substantial cash payments for abstinence. Such an approach may only be feasible where independently-funded smoking cessation programmes are already available, and within a relatively affluent and educated population. Deposit-refund trials can suffer from relatively low rates of uptake, but those who do sign up and contribute their own money may achieve higher quit rates than reward-only participants. Incentive schemes conducted among pregnant smokers improved the cessation rates, both at the end-of-pregnancy and post-partum assessments. Current and future research might continue to explore the scale, loading and longevity of possible cash or voucher reward schedules, within a variety of smoking populations.