Randomized Controlled Trial Examining the Efficacy of Adding Financial Incentives to Best practices for Smoking Cessation Among pregnant and Newly postpartum Women

Abstract

We report results from a single-blinded randomized controlled trial examining financial incentives for smoking cessation among 249 pregnant and newly postpartum women. Participants included 169 women assigned to best practices (BP) or BP plus financial incentives (BP + FI) for smoking cessation available through 12-weeks postpartum. A third condition included 80 never-smokers (NS) sociodemographically-matched to women who smoked. Trial setting was Burlington, Vermont, USA, January, 2014 through January, 2020. Outcomes included 7-day point-prevalence abstinence antepartum and postpartum, and birth and other infant outcomes during 1st year of life. Reliability and external validity of results were assessed using pooled results from the current and four prior controlled trials coupled with data on maternal-smoking status and birth outcomes for all 2019 singleton live births in Vermont. Compared to BP, BP + FI significantly increased abstinence early- (AOR = 9.97; 95%CI, 3.32-29.93) and late-pregnancy (primary outcome, AOR = 5.61; 95%CI, 2.37-13.28) and through 12-weeks postpartum (AOR = 2.46; CI,1.05-5.75) although not 24- (AOR = 1.31; CI,0.54-3.17) or 48-weeks postpartum (AOR = 1.33; CI,0.55-3.25). There was a significant effect of trial condition on small-for-gestational-age (SGA) deliveries (χ² [2] = 9.01, P = .01), with percent SGA deliveries (+SEM) greatest in BP, intermediate in BP + FI, and lowest in NS (17.65 + 4.13, 10.81 + 3.61, and 2.53 + 1.77, respectively). Reliability analyses supported the efficacy of financial incentives for increasing abstinence antepartum and postpartum and decreasing SGA deliveries; external-validity analyses supported relationships between antepartum cessation and SGA risk. Adding financial incentives to Best Practice increases smoking cessation among antepartum and postpartum women and improves other maternal-infant outcomes. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02210832.

Keywords: Cost-effectiveness; birth outcomes; cigarette smoking; contingency management; financial incentives; pregnancy; small-for-gestational-age delivery; smoking cessation.

Figure 1.

CONSORT diagram on participant enrollment and randomization.

Figure 2.

Seven-day point-prevalence abstinence outcomes for the Best Practices and Best Practices + Financial Incentives conditions in the current trial (top panel) and Financial Incentives and Control conditions in the pooled trials (bottom panel). X axes show consecutive assessments (early antepartum [Early AP], late antepartum [Late AP], weeks 2–48 postpartum (PP) (top panel) or 2–24 postpartum (PP) (bottom panel). Y axes show percent of participants abstinent. Asterisks represent assessments where abstinence was significantly greater in Best Practices + Financial Incentives compared to Best Practices (top panels) or Financial Incentives compared to Controls (bottom panels). Significance represents P < .05.

Figure 3.

Mean Minnesota Nicotine Withdrawal Scale (MNWS) Craving (‘Desire to Smoke’ item) ratings and Total Scores from current trial are shown in the upper left and right panels, respectively, and those from the pooled trials are shown in the bottom left and right panels, respectively. Mean scores are shown on the Y axes and assessment times on the X axes (early antepartum (Early AP) and late antepartum (Late AP) assessments followed by postpartum (PP) weeks 2–48 (current trial) and 2–24 (pooled trials). Asterisks represent specific assessments where values in Best Practices +Financial Incentives were significantly lower than Best Practices in upper left and right panels; in the lower left panel asterisks represent specific assessments where values in Financial Incentives were significantly lower than Controls; the bracket in the lower right panel represents a significant main effect of trial condition where scores were significantly lower in Financial incentives than Controls and a significant main effect of time where scores in both trial conditions decreased over time, with no significant interaction of trial condition and time. Significance represents P < .05.

Figure 4.

Small for gestational age (SGA) deliveries by trial condition in the current trial (top panel) and pooled trials (bottom panel). Left-most upper and lower panels show analyses including all infants while right-most upper and lower panels show results for term infants. BP = Best Practices (n=88 all infants; n=79 term infants), BP+FI = Best Practices + Financial Incentives (n=81 all infants; n=65 term infants), NS= Never-smokers (n=80 all infants; n=71 term infants), C = Control Conditions (n=202 all infants; n=179 term infants), and FI = Financial Incentives (n=234 all infants; n=213 term infants). Conditions not sharing a superscript letter differ significantly at P < .05.

Figure 5.

Small for gestational age (SGA) deliveries for all 2019 singleton births in Vermont overall and separated by maternal insurance status. NS= Never-smokers, S = Smokers throughout pregnancy, and S+Q = Smokers who quit during the pregnancy. Conditions not sharing a superscript letter differ significantly at P < .05.