A larger context for considering the Tappin et al. report on financial incentives for smoking cessation in pregnant and newly postpartum women
We commend Dr. Tappin and colleagues on an important study and report. As is carefully reviewed in their report, smoking during pregnancy and postpartum is associated with many serious adverse maternal and infant health outcomes. Yet after almost 30 years of treatment development research in this area, there remains a tremendous need for more effective interventions. The Tappin et al. report provides additional evidence from a relatively large and rigorously controlled trial that financial incentives in the form of vouchers exchangeable for retail items increase abstinence rates several fold above cessation rates achieved with other psychosocial and pharmacological interventions.
We want to contribute several points of information not mentioned by Tappin and colleagues that warrant consideration regarding the potential merits of this treatment approach, often referred to as Contingency Management in the substance abuse literature. First, there is a large body of experimental evidence in the form of rigorously controlled randomized clinical trials and meta-analyses supporting the efficacy of this treatment approach for increasing abstinence from a wide range of different abused drugs including cocaine, marijuana, methamphetamine, opioids, and tobacco.1,2 Indeed, a NICE Guidelines report appeared in the BMJ in 2007 recommending implementation of this treatment approach in community substance abuse treatment centers in the United Kingdom.3 When considered in this larger context, the accumulating evidence supporting the efficacy of this approach with pregnant cigarette smokers is not surprising.
Second, there is increasing evidence that the intervention improves important health outcomes among pregnant and newly postpartum women and their infants. For example, there are two randomized controlled clinical trials demonstrating that this treatment approach increases sonographically estimated fetal growth in the third trimester.4,5 Results from several studies that combined data sets across controlled trials conducted in the same clinic along with appropriate statistical adjustments for doing so, suggest that the intervention can increase mean birth weight and decrease percent of low birth weight deliveries6, increase the duration of breastfeeding7, and decrease postpartum depressive symptomatology in depression-prone women.8
Third, the large literature on the use of voucher-based incentives in treatment of substance abuse allows us to glean some evidence-based guideposts. One such guidepost is that the size of the treatment effect generally increases as an orderly function of the monetary amount of the incentive provided.2 Tappin and colleagues used a smaller maximal incentive value than has been used in several prior trials with pregnant smokers (£400 versus ~$1,100). As expected, treatment effect size also appears to be relatively smaller, with absolute late-pregnancy abstinence levels of 22% in the Tappin et al report versus an average of 35-45% in the prior efficacy trials that used the $1,100 value and differences above control levels of 13.9% in the Tappin et al. report versus ~25% in the prior reports.4,5,9 This is certainly not a criticism of the abstinence outcomes achieved by Tappin and colleagues, which were 2.6-fold greater than control levels. Instead, the intent of this comment is to get this important information on the relationship between incentive value and treatment effect size into the conversation about where to set intervention parameters when using this treatment with pregnant smokers. The likelihood of impacting birth and other health outcomes mentioned above can also be expected to vary by the size of the treatment effect on smoking abstinence as can the likelihood of significantly impacting longer-term maternal abstinence rates and related risk of second-hand smoke exposure among the children, etc. Future parametric trials examining the impact of varying incentive value on abstinence and related health outcomes in pregnant women and their infants, along with associated cost-effectiveness analyses, would be very helpful in answering this important parametric question. There are also other important parametric questions to be addressed regarding the optimal frequency of clinic contact and different ways of scheduling voucher delivery that also merit serious consideration.10,11
A fourth and final point has to do with predictors of individual differences in response to voucher-based incentives that we feel underscores the importance of ongoing dialogue among investigators in this area. Tappin et al. report that baseline socioeconomic indicators (Scottish Index of Multiple Deprivations) and nicotine dependence levels (selected individual items and average scores from Fagerstrom questionnaire) did not predict treatment response. In prior research on this same topic, years of educational attainment and cigarettes smoked per day pre-pregnancy or at first antepartum prenatal care visit were robust predictors of end-or-pregnancy abstinence within the incentives condition.11,12 We did not see either of these potential predictors mentioned by Tappin and colleagues, but they are worth examining if they are available in this data set.
1. Higgins ST, Silverman K, Heil SH, editors. Contingency management in substance abuse treatment. New York: The Guilford Press; 2008.
2. Lussier JP, Heil SH, Mongeon JA, Badger GJ, Higgins ST. A meta-analysis of voucher-based reinforcement therapy for substance use disorders. Addiction. 2006;101:192–203.
3. Pilling S, Strang J, Gerada C. Psychosocial interventions and opioid detoxification for drug misuse: summary of NICE guidelines. BMJ. 2007; 335: 203-205.
4. Heil SH, Higgins ST, Bernstein IM, Solomon LJ, Rogers RE, Thomas CS, Badger GJ, Lynch ME. Effects of voucher-based incentives on abstinence from cigarette smoking and fetal growth among pregnant women. Addiction. 2008;103:1009-18.
5. Higgins ST, Washio Y, Lopez AA, Heil SH, Solomon LJ, Lynch ME, Hanson JD, Higgins TM, Skelly JM, Redner R, Bernstein IM.. Examining two different schedules of financial incentives for smoking cessation among pregnant women. Prev Med. 2014;68:51-7.
6. Higgins ST, Bernstein IM, Washio Y, Heil SH, Badger GJ, Skelly JM, Higgins TM, Solomon LJ. Effects of smoking cessation with voucher-based contingency management on birth outcomes. Addiction. 2010;105:2023-30.
7. Higgins TM, Higgins ST, Heil SH, Badger GJ, Skelly JM, Bernstein IM, Solomon LJ, Washio Y, Preston AM. Effects of cigarette smoking cessation on breastfeeding duration. Nicotine Tob Res. 2010;12:483-8.
8. Lopez AA, Skelly JM, Higgins ST. Financial incentives for smoking cessation among depression-prone pregnant and newly postpartum women: effects on smoking abstinence and depression ratings. Nicotine Tob Res. In press.
9. Higgins ST, Heil SH, Solomon LJ, Bernstein IM, Lussier JP, Abel RL, Lynch ME, Badger GJ. A pilot study on voucher-based incentives to promote abstinence from cigarette smoking during pregnancy and postpartum. Nicotine Tob Res. 2004;6:1015-20.
10. Donatelle R, Hudson D, Dobie S, Goodall A, Hunsberger M, Oswald K. Incentives in smoking cessation: status of the field and implications for research and practice with pregnant smokers. Nicotine Tob Res. 2004;6 Suppl 2:S163-79.
11. Higgins ST, Washio Y, Heil SH, Solomon LJ, Gaalema DE, Higgins TM, Bernstein IM. Financial incentives for smoking cessation among pregnant and newly postpartum women. Prev Med. 2012;55 Suppl:S33-40.
12. Higgins ST, Heil SH, Badger GJ, Skelly JM, Solomon LJ, Bernstein IM. Educational disadvantage and cigarette smoking during pregnancy. Drug Alcohol Depend. 2009; 1;104 Suppl 1:S100-5.
Competing interests: No competing interests