Health-promoting behaviors include the ‘big four’ behaviors of not smoking, sensible alcohol consumption, eating a ‘healthy’ diet, and taking regular physical activity; as well as safe sun and sex behaviors and primary preventive clinical behaviors, such as attending for vaccinations and screening. Poor engagement in these behaviors is a key determinant of morbidity and mortality and results in substantial social, healthcare and economic costs. Despite consistent efforts to encourage uptake of healthy behaviors
[1, 2], unhealthy behaviors remain common.
In general, behavioral incentives have been defined as motivating rewards that are provided contingent on behavioral performance
. However, this definition could be interpreted as including any reward (for example, a sticker or praise) and not just financial rewards. Furthermore, this definition specifically excludes the converse of motivating rewards - penalties. While non-financial rewards may also increase health promoting behaviors, it is highly likely that in advanced societies, interventions offering financial rewards are conceptually different from those offering rewards with social, emotional or tokenistic value. As such, this review is restricted to financial incentives and penalties and we define these as interventions that offer cash or cash-like rewards (for example, vouchers that can be exchanged for goods or services) contingent on performance of the target healthy behavior, but widen this to include interventions imposing cash or cash-like (for example, reductions in welfare benefits) penalties contingent on non-performance of the target healthy behavior. Hence forth we use the term ‘financial incentives’ to refer to both these incentives and penalties.
The reasons why individuals pursue unhealthy behaviors are diverse and include environmental, social, psychological and socio-demographic factors
. One further reason relates to the relative balance and timing of the costs and rewards of engaging in these behaviors, and personal preferences for these (that is, ‘time preference’). Behavioral economic theory suggests that individuals commonly hold inconsistent preferences for similar outcomes occurring at different points in the future, with outcomes in the near future generally valued more than those in the distant future
. While the health gains of health-promoting behaviors are often delayed in time, the financial and opportunity costs can be immediate. As these immediate costs are ‘dis-valued’ more than the delayed health benefits are valued, individuals make a ‘rational’ choice to pursue unhealthy behaviors. Providing immediate rewards for performance of health behaviors, or penalties for non-performance is likely to change the temporal reward structure associated with these behaviors, working with, rather than against, individuals’ time preferences
Using financial incentives to encourage uptake of healthy behaviors may appear to be a simple solution to a serious public health problem. However, these interventions are not simple. They differ in terms of the behavior incentivized; the value, nature (that is, reward or penalty; cash or voucher) and timing (that is, immediately following, or remote from, performance of the behavior) of the incentive; as well as the other behavioral change techniques that may be incorporated into the programs of which they are a part (for example, keeping a record of the target behavior or agreeing to a behavioral contract)
. While there is a growing range of evaluations of financial incentives for encouraging uptake of healthy behaviors
[9–14], conclusions on what makes an effective financial incentive program in this context remain limited to the suggestion that incentives are more useful for encouraging simple one-off behaviors, such as attendance for vaccinations, than more complex sustained behavior changes, such as smoking cessation
[7, 13, 15]. In addition, variations in the effectiveness of financial incentives across population groups have not been explored. The apparent failure of many financial incentive programs to achieve sustained behavioral change may reflect sub-optimal design of the intervention, rather than a failure of incentives per se.
A number of systematic and non-systematic reviews have been conducted in this area
[9–14, 16, 17]. However, most focus on individual behaviors (for example, smoking or weight loss), rather than exploring the full range of healthy behaviors, or are restricted to developing countries where absolute financial hardship may be much more common
. The current review will fill this gap by conducting a systematic review of primary studies which explore the use of financial incentives to encourage uptake of the full range of healthy behaviors. As described below, systematic procedures will be used to search the literature and identify reports of research for inclusion. An established tool for assessing the quality of included reports will be used to grade the quality of existing evidence. A narrative and tabular summary of the existing evidence will be produced. The potential for meta-analysis will be explored and this will be conducted if appropriate.
The UK Secretary of State for Health has signaled his interest in using financial incentives for encouraging uptake of healthy behaviors
 and the UK National Institute for Health and Clinical Excellence is consulting on the topic
. This research will provide policy-relevant information for the design of evidence-based financial incentive interventions which can be subjected to robust evaluation.
This systematic review will answer the following primary research question:
What is the effectiveness of financial incentives for encouraging uptake of healthy behaviors among adults living in high-income countries?
Secondary research questions are:
What formats do financial incentives in included studies take (for example, cash, coupons, vouchers, pay deductions)?
What is the range of healthy behaviors that have been targeted (for example, smoking, physical activity, dietary behaviors, alcohol consumption, safe sun, safe sex, and primary preventive clinical behaviors)?
Apart from the incentive component, what other behavior change techniques are used as part of these interventions?
What theoretical rationales have been used to guide intervention development?
Does effectiveness of financial incentive programs vary according to:
the length of the intervention period?
the length of the follow up period, after the active intervention ceases?
the format of the incentive (for example, cash, voucher, reward, penalty, total value)?
the nature of the behavior incentivized (for example, one-off, sustained behavior change)?
socio-demographic characteristics (for example, age, gender, socio-economic position) of recipients?
inclusion of other behavior change techniques in the intervention program?