Smoking rates have declined dramatically in the United States but remain high in the Medicaid population [
We developed and tested a novel approach to smoking cessation incentives, in an attempt to create a cost-effective intervention for Medicaid populations. Specifically, to reinforce standard cessation efforts, we combined incentives with deposit contracts that could be funded with earned incentives.
Financial incentives have been shown to improve smoking cessation rates in many populations [
Deposit contracts, whereby participants forfeit their own money if a cessation target is not met, are effective on average. However, they exhibit low take-up rates as people seem reluctant to put their own money on the line [
To test the efficacy of our combined financial incentives and deposit contract intervention, we randomly assigned 311 smokers covered by Medicaid to usual care or one of the three treatment arms receiving financial incentives for two months and (i) nothing further (“incentives only”), (ii) the option to start to a deposit contract with any incentives earned, offered at the end of the incentive program (“commitment”), or (iii) the option to precommit any incentives earned to a deposit contract starting after the incentives ended, offered at the beginning of the incentive program (“precommitment”).
Our hypothesis was that financial incentives would increase cessation rates for all treatment groups relative to usual care in the short term, i.e., when measured at two months. Drawing on the deposit contract literature (for an overview, see [
In November 2015, we started enrolling Medicaid participants from a large statewide Federally Qualified Health Center (FQHC) in Connecticut in a smoking cessation program. Eligibility criteria were being a daily smoker over 18 years old, wanting to quit smoking, and having a clinic visit in the past two years. Our initial aim, based on power calculations, was to recruit 1500 participants over two years. The target sample size was chosen based on power calculations to detect, with 80% power and a 5% significance threshold: (1) a treatment effect of 4 percentage points for the incentive-only arm compared to a control group mean cessation rate of 3 percent, (2) a treatment effect of the pooled deposit contract arms of 4 percentage points for the incentive arm compared to a control group cessation rate, (3) a 7 percentage point difference in treatment effect between the incentive-only and pooled deposit contract arms assuming a mean cessation rate of 7 percent in the incentive-only arm, and (4) a 9 percentage point increase in deposit contract take-up in the precommitment arm compared to the commitment arm assuming take-up of 10 percent in the commitment arm.
However, staffing challenges forced us to scale back recruitment. Specifically, the staff allocated for recruitment by clinics did not have enough time to meet recruitment targets and manage their other clinic-based duties. We lacked the resources required to hire dedicated recruitment staff and consequently ended up enrolling only 311 participants between November 2015 and October 2016.
At enrollment, participants completed a short baseline survey with questions about demographics and smoking-related behaviors. Specifically, we asked about marital status, the highest level of education completed, the number of individuals living in the household, household income, pregnancy status, and the number of hours with Internet access a week. The baseline survey also contained questions for the Fagerstrom index as well as questions about the participant’s smoking history and previous quit attempts. The study was approved by the Institutional Review Board (IRB) of Community Health Center, Inc.
The trial was as a multiarm parallel-group study with simple randomization and no blinding. We randomly assigned the 311 study participants, at the participant level, with a 1 : 1 : 0.5 : 0.5 split, to either usual care (
All study participants were encouraged to use the clinic’s usual care cessation support services, including individual counselling, group counseling and nicotine replacement therapy, and the state’s quitline. Clinic staff informed participants about available services in-person after enrollment and gave participants a small brochure with the same information.
Participants in the incentive-only group were offered usual care, plus $200 for biochemically verified smoking cessation measured at two months and up to $100 for cessation support activities during the first two months, including group and individual counselling, for a total possible reward of $300. Rewards were paid at the conclusion of the first two months, via a gift card redeemable at a large supermarket chain.
Participants in the commitment and the precommitment were offered deposit contracts lasting for four months after the incentive period, in addition to the same financial incentives and usual care offered to the incentive-only group. In the commitment group, after the incentive earning period, participants who were verified as having quit smoking were asked after the incentive period if they wanted to transfer all or part of their earnings into a deposit contract. Clinic staff helped interested participants through the deposit contract setup process, usually during the participant’s clinic visit to verify cessation. In the precommitment group, participants had the option at baseline to automatically transfer all or part of any future earned incentive into a deposit contract. Clinic staff helped participants who elected this option set up their deposit contract during study enrollment.
During study enrollment, all participants assigned to treatment arms were registered for a study-specific portal on a website that provides goal monitoring and online deposit contracts (
The primary outcomes are biochemically verified smoking cessation at two, six, and twelve months after enrollment. Clinic staff contacted participants by phone and asked them to make an appointment at the clinic to verify their smoking cessation status. Appointments had to be made within a two-week window of each time milestone. Only participants who reported cessation on the phone were asked to validate it with a CO breathalyzer and urine cotinine test. We defined cessation as having a CO reading below 8 ppm and a urine cotinine level below or equal to 20 ng/mL. Passing the CO test is not an outcome itself but was instead used as a filter to reduce the number of participants requiring a urine cotinine test. Any participant who did not provide biochemical verification in the form of a urine cotinine test was recorded as still smoking. Our secondary outcomes are the number of cessation support prescriptions written and the number of counseling sessions attended.
All analyses compare outcomes in the usual care group to outcomes in each treatment group and to outcomes for any treatment group. Our primary analyses use multivariate logistic regressions to compare the likelihood of biochemically confirmed cessation at two, six, and twelve months. We use ordinary least squares (OLS) to compare total counseling sessions attended and total support prescriptions written across groups. All analyses are on an intent-to-treat basis and estimated with and without demographic controls (including age as a continuous measure, binary indicators for sex and high school as the highest education level, and several indicators for income bins). Analyses were conducted in 2019 using Stata version 15. We preregistered the study with ClinicalTrials.gov (study identifier:
All study participants (
Baseline characteristics of study participants.
Characteristic | Control ( | Any treatment ( | Treatment groups | |||
---|---|---|---|---|---|---|
Incentives only ( | Commitment ( | Precommitment ( | ||||
Female | 0.62 | 0.58 | 0.62 | 0.57 | 0.53 | 0.11 |
Age | 45.94 (10.66) | 45.25 (10.98) | 45.94 (10.66) | 46.17 (11.62) | 43.36 (11.03) | 0.05 |
Married | 0.14 | 0.14 | 0.14 | 0.20 | 0.10 | 0.08 |
Race or ethnic group (%) | ||||||
Race: Black or African American | 0.27 | 0.31 | 0.27 | 0.40 | 0.32 | 0.35 |
Race: White | 0.50 | 0.45 | 0.50 | 0.48 | 0.34 | 0.94 |
Race: Other | 0.22 | 0.24 | 0.22 | 0.12 | 0.34 | 0.39 |
Hispanic | 0.26 | 0.27 | 0.26 | 0.14 | 0.37 | 0.16 |
Level of education (%) | ||||||
High school or lower | 0.72 | 0.69 | 0.72 | 0.61 | 0.71 | 0.52 |
Associate’s or Bachelor’s degree | 0.15 | 0.20 | 0.15 | 0.29 | 0.24 | 0.20 |
Graduate degree | 0.14 | 0.10 | 0.14 | 0.10 | 0.05 | 0.57 |
Household income (%) | ||||||
$10,000 or under | 0.56 | 0.54 | 0.56 | 0.50 | 0.53 | 0.41 |
$10,001 to $30,000 | 0.34 | 0.33 | 0.34 | 0.38 | 0.27 | 0.54 |
$30,001 to $50,000 | 0.03 | 0.06 | 0.03 | 0.12 | 0.08 | 0.79 |
$50,001 and above | 0.07 | 0.07 | 0.07 | 0.00 | 0.12 | 0.39 |
Smoking behaviors | ||||||
Smoking more than 20 cigarettes a day | 0.02 | 0.03 | 0.02 | 0.05 | 0.05 | 0.13 |
Quit attempts in the last year | 2.00 (41.28) | 2.00 (40.74) | 2.00 (41.28) | 1.00 (1.91) | 1.00 (52.44) | 0.79 |
Has quit 1 year or more since starting smoking | 0.18 | 0.18 | 0.18 | 0.12 | 0.24 | 0.55 |
Fagerstrom score for nicotine dependence | ||||||
Low dependence | 0.07 | 0.08 | 0.07 | 0.10 | 0.08 | 0.49 |
Low to moderate dependence | 0.23 | 0.25 | 0.23 | 0.26 | 0.27 | 0.56 |
Moderate dependence | 0.36 | 0.35 | 0.36 | 0.31 | 0.34 | 0.18 |
High dependence | 0.17 | 0.15 | 0.17 | 0.19 | 0.10 | 0.67 |
Note: values represent means (SD) unless otherwise indicated. Median reported due to outliers (4 participants responded 365).
Table
Analysis of the treatment effect on primary and secondary outcomes.
Incentives only | Commitment | Precommitment | Any treatment | |||||
---|---|---|---|---|---|---|---|---|
OR or coef. [95% CI] | OR or coef. [95% CI] | OR or coef. [95% CI] | OR or coef. [95% CI] | |||||
No demographic controls | ||||||||
Primary outcomes (OR) | ||||||||
Passed urine test at 2 m | 1.36 [0.52 : 3.53] | 0.53 | 1.98 [0.64 : 6.10] | 0.23 | 1.86 [0.66 : 5.26] | 0.24 | 1.62 [0.70 : 3.73] | 0.26 |
Passed urine test at 6 m | 2.48 [0.47 : 13.06] | 0.29 | 1.23 [0.11 : 13.96] | 0.87 | 4.68 [0.88 : 24.91] | 0.07 | 2.82 [0.61 : 12.97] | 0.18 |
Secondary outcomes (OLS coefficients) | ||||||||
Total support counselling sessions attended | 0.25 [-0.66 : 1.16] | 0.59 | -0.21 [-0.80 : 0.38] | 0.48 | -0.06 [-0.82 : 0.69] | 0.87 | 0.07 [-0.55 : 0.69] | 0.82 |
Total support prescriptions given | -0.17 [-0.53 : 0.19] | 0.35 | -0.24 [-0.59 : 0.12] | 0.20 | -0.31 [-0.75 : 0.13] | 0.17 | -0.22 [-0.53 : 0.08] | 0.15 |
With demographic controls | ||||||||
Primary outcomes (OR) | ||||||||
Passed urine test at 2 m | 1.71 [0.53 : 5.51] | 0.37 | 3.24 [0.86 : 12.25] | 0.08 | 3.03 [0.85 : 10.79] | 0.09 | 2.31 [0.81 : 6.60] | 0.12 |
Passed urine test at 6 m | 0.89 [0.13 : 6.03] | 0.90 | 0.84 [0.06 : 11.07] | 0.89 | 4.08 [0.70 : 23.90] | 0.12 | 1.65 [0.33 : 8.37] | 0.54 |
Secondary outcomes (OLS coefficients) | ||||||||
Total support counselling sessions attended | 0.08 [-0.74 : 0.89] | 0.86 | -0.16 [-0.93 : 0.61] | 0.68 | -0.36 [-1.14 : 0.43] | 0.37 | -0.09 [-0.66 : 0.48] | 0.75 |
Total support prescriptions given | -0.16 [-0.52 : 0.21] | 0.40 | -0.19 [-0.58 : 0.20] | 0.34 | -0.33 [-0.70 : 0.04] | 0.08 | -0.21 -0.52 : 0.09] | 0.17 |
Note: usual care is the reference group. Logistic regressions for the binary outcomes “passed urine test at 2 m” and “passed urine test at 6 m” and ordinary least squares (OLS) for the remaining outcomes. OR refers to the odds ratio from a logistic regression, and coef. refers to the coefficient from an OLS regression. Demographic controls include age, sex, an indicator for high school as the highest education level, and income bin indicators.
Our estimates for all time periods are imprecise in that they include a wide range of possible effect sizes. A recent meta-analysis of 30 studies comparing incentives (including deposit contracts) for smoking cessation against no incentives finds an odds ratio of 1.49 (CI: 1.28-1.73) at the longest follow-up (typically 6 months). Our confidence intervals include this point estimate and those from other meta-analyses of the literature [
Table
We tested a novel combination of incentives and deposit contracts among clinic-based Medicaid participants who indicated interest in smoking cessation. The relatively high take-up of commitment contracts in the precommitment arm suggests that creative deposit contracts are feasible additions to financial incentive programs—the take-up rate was higher than that seen in other studies offering deposit contracts for smoking cessation without precommitment and higher than that in our commitment arm in this study. But the incentives did not increase cessation enough to permit identification of the ultimate effect of precommitment on cessation rates. The precommitted deposit contracts ended up lacking commitment value for continued smoking cessation during the two-month to six-month period for smoking cession, because the financial incentives did not induce cessation during the initial two-month period and hence most precommitted contracts were not funded.
Our study has several limitations. First and foremost, our estimates are not precise enough to make strong inferences about the efficacy of financial incentives and deposit contracts within the target population. The point estimates for the cessation rates are in line with those observed in other studies of financial incentives for smoking cessation, but our estimates are imprecise due to lower than planned enrollment. The design of our incentive program is comparable to successful previously tested programs. For example, a study with Medicaid enrollees finds a statistically significant increase in cessation rates from a similar incentive schedule to this study: $30 per counselling call and $40 for biochemically verified smoking cessation at six months with a total incentive amount of $190 [
Third, not all participants engaged with the website portal. For example, only 37% of treatment participants submitted a journal entry within the two-month intervention window. Internet access or literacy (which we did not measure) was likely a barrier for some, but 73% of our study population did have daily Internet access. Our intervention might be improved by better educating participants on how to use the website portal and better explaining the functioning of the deposit contracts.
We conjecture that a combination of process incentives for using formal cessation services and outcome incentives for cessation, delivered through a mix of earned incentives and deposit contracts, may be fruitful for a Medicaid population. Further exploration should focus on improving enrollment and thus increasing the statistical precision of treatment effect estimates. Future work also could test other aspects of incentive and deposit contract design and implementation. We suggest testing more frequent incentives, more opportunities to precommit incentives, more information on the likelihood of succeeding, and more information on the likelihood of reverting to smoking.
The data reported in this paper have been deposited in the Innovations for Poverty Action Dataverse (
The authors declare that they have no conflicts of interest.
We thank Caton Brewster for the excellent research assistance. This study was supported by the J-PAL North America Health Care Delivery Initiative.