Shaping smoking cessation in hard-to-treat smokers

Abstract

Objective: Contingency management (CM) effectively treats addictions by providing abstinence incentives. However, CM fails for many who do not readily become abstinent and earn incentives. Shaping may improve outcomes in these hard-to-treat (HTT) individuals. Shaping sets intermediate criteria for incentive delivery between the present behavior and total abstinence. This should result in HTT individuals having improving, rather than poor, outcomes. We examined whether shaping improved outcomes in HTT smokers (never abstinent during a 10-visit baseline).

Method: Smokers were stratified into HTT (n = 96) and easier-to-treat (ETT [abstinent at least once during baseline]; n = 50) and randomly assigned to either CM or CM with shaping (CMS). CM provided incentives for breath carbon monoxide (CO) levels <4 ppm (approximately 1 day of abstinence). CMS shaped abstinence by providing incentives for COs lower than the 7th lowest of the participant's last 9 samples or <4 ppm. Interventions lasted for 60 successive weekday visits.

Results: Cluster analysis identified 4 groups of participants: stable successes, improving, deteriorating, and poor outcomes. In comparison with ETT, HTT participants were more likely to belong to 1 of the 2 unsuccessful clusters (odds ratio [OR] = 8.1, 95% CI [3.1, 21]). This difference was greater with CM (OR = 42, 95% CI [5.9, 307]) than with CMS, in which the difference between HTT and ETT participants was not significant. Assignment to CMS predicted membership in the improving (p = .002) as compared with the poor outcomes cluster.

Conclusion: Shaping can increase CM's effectiveness for HTT smokers.

Figure 1

Consort Flow Chart. Outcomes were based on during intervention smoking behavior and analyzed on an intent to treat basis.

Figure 2

Outcome trajectories for the four-cluster solution. The mean percentage of breath samples meeting the criterion for 1-day abstinence (i.e., CO < 4 ppm) are shown for each cluster in each block of 10 study visits. Dashed lines represent unsuccessful outcomes (poor outcomes –filled points, N=52; and deteriorating – open points, N=19) and solid lines represent successful outcomes (stable success – open points, N=66; and improving – filled points, N=9).

Figure 3

Event records for each individual grouped together into clusters. Top panel presents data for the Easier to Treat, who had a CO < 4 ppm before the start of the interventions at visit 11. Bottom panel presents data for the Hard to Treat, who did not have a CO < 4 ppm before the start of the intervention. Dark spaces represent breath CO levels < 4 ppm, while lighter spaces represent breath CO levels ≥ 4 ppm. Empty spaces represent missed visits. The Horizontal axis is sequential visits and each ‘line’ of data represents an individual subject. The vertical line in each column separates the tenth and eleventh visit and indicates when the experimental contingencies went into effect. The left column is participants receiving CM, and the right column is participants receiving CMS.