A Psychometric Evaluation of the Stanford Expectations of Treatment Scale (SETS) in the Context of a Smoking Cessation Trial.

INTRODUCTION: Although treatment outcome expectancies (TOEs) may influence clinical outcomes, TOEs are rarely reported in the smoking cessation literature, in part because of the lack of validated measures. Therefore, we conducted a psychometric evaluation of TOEs scores with the Stanford Expectations of Treatment Scale (SETS) in the context of a smoking cessation clinical trial. METHODS: Participants were 320 adults enrolled in a randomized controlled trial of extended versus standard pre-quit varenicline treatment for smoking cessation (clinicaltrials.gov ID: NCT03262662). Across an 8-week treatment period, we examined the nature and stability of the factor structure using confirmatory factor analysis (CFA), evaluated discriminant validity by examining correlations with abstinence self-efficacy and positive/negative affect (PA/NA), and assessed internal consistency and test-retest reliability of SETS scores. RESULTS: CFAs supported a 2-factor structure that was stable (ie, invariant) across weeks. Positive and negative TOEs were each reflected in three-item subscales that exhibited acceptable to excellent internal consistency (Cronbach's alphas ≥ .77). Positive and negative TOEs were modestly correlated with PA and NA (all |rs| <.27, p < .05). Positive TOEs, but not negative TOEs, were moderately correlated with abstinence self-efficacy (rs = .45 to .61, p < .01). Both positive and negative TOEs scores demonstrated moderate test-retest reliability between assessments (rs = .54 to .72). CONCLUSIONS: SETS scores generally reflect a valid and reliable assessment of positive and negative TOEs in a sample of adults enrolled in a smoking cessation trial. The SETS appears to be a reasonable option for assessing TOEs in future smoking treatment studies. IMPLICATIONS: Assessments of treatment outcome expectancies are rarely reported in the smoking cessation literature. The present results support the validity and reliability of the SETS scores among adults seeking treatment for their smoking behavior.

Evaluating Treatment Mechanisms of Varenicline: Mediation by Affect and Craving.

INTRODUCTION: Negative reinforcement models posit that relapse to cigarette smoking is driven in part by changes in affect and craving during the quit attempt. Varenicline may aid cessation by attenuating these changes; however, this mediational pathway has not been formally evaluated in placebo-controlled trials. Thus, trajectories of negative affect (NA), positive affect (PA), and craving were tested as mediators of the effect of varenicline on smoking cessation. AIMS AND METHODS: Secondary data analysis was conducted on 828 adults assigned to either varenicline or placebo in a randomized controlled trial for smoking cessation (NCT01314001). Self-reported NA, PA, and craving were assessed 1-week pre-quit, on the target quit day (TQD), and 1 and 4 weeks post-TQD. RESULTS: Across time, NA peaked 1-week post-quit, PA did not change, and craving declined. Less steep rises in NA (indirect effect 95% CI: .01 to .30) and lower mean craving at 1-week post-quit (CI: .06 to .50) were mediators of the relationship between varenicline and higher cessation rates at the end of treatment. PA was associated with cessation but was not a significant mediator. CONCLUSIONS: These results partially support the hypothesis that varenicline improves smoking cessation rates by attenuating changes in specific psychological processes and supported NA and craving as plausible treatment mechanisms of varenicline. IMPLICATIONS: The present research provides the first evidence from a placebo-controlled randomized clinical trial that varenicline's efficacy is due, in part, to post-quit attenuation of NA and craving. Reducing NA across the quit attempt and craving early into the attempt may be important treatment mechanisms for effective interventions. Furthermore, post-quit NA, PA, and craving were all associated with relapse and represent treatment targets for future intervention development.

The impact of three weeks of pre-quit varenicline on reinforcing value and craving for cigarettes in a laboratory choice procedure.

RATIONALE: Varenicline, a partial nicotinic agonist, is theorized to attenuate pre-quit smoking reinforcement and post-quit withdrawal and craving. However, the mechanisms of action have not been fully characterized, as most studies employ only retrospective self-report measures, hypothetical indices of reinforcing value, and/or nontreatment-seeking samples. OBJECTIVES: The current research examined the impact of pre-quit varenicline (vs. placebo) on laboratory measures of smoking and food (vs. water) reinforcement and craving. METHODS: Participants were 162 treatment-seeking smokers enrolled in a randomized controlled trial of smoking cessation ( clinicaltrials.gov ID: NCT03262662). Participants completed two laboratory sessions: a pre-treatment session, ~ 1 week prior to beginning varenicline or placebo, and an active treatment session, after ~ 3 weeks of treatment. At each session, participants completed a laboratory choice procedure; on each of 36 trials, a lit cigarette, food item, or cup of water was randomly presented. Participants reported level of craving and spent $0.01-0.25 to have a corresponding 5-95% chance to sample the cue. RESULTS: As predicted, spending was significantly higher on cigarette trials than water trials, and varenicline resulted in a greater between-session decline in spending on cigarette trials (but not water) than did placebo. Cigarette craving was enhanced in the presence of smoking cues compared to water, but neither average (tonic) cigarette craving nor cue-specific cigarette craving was significantly influenced by varenicline. Food spending and craving were generally unaffected by varenicline treatment. CONCLUSIONS: These laboratory data from treatment-seeking smokers provide the strongest evidence to date that varenicline selectively attenuates smoking reinforcement prior to quitting.

Withdrawal Symptom, Treatment Mechanism, and/or Side Effect? Developing an Explicit Measurement Model for Smoking Cessation Research.

INTRODUCTION: Assessment of withdrawal symptoms, treatment mechanisms, and side effects is central to understanding and improving smoking cessation interventions. Though each domain is typically assessed separately with widely used questionnaires to separately assess each domain (eg, Minnesota Nicotine Withdrawal Scale = withdrawal; Questionnaire of Smoking Urges-Brief = craving; Positive and Negative Affect Schedule = affect; symptom checklist = side effects), there are substantial problems with this implicit "one questionnaire equals one construct" measurement model, including item overlap across questionnaires. This study sought to clarify the number and nature of constructs assessed during smoking cessation by developing an explicit measurement model. METHODS: Two subsamples were randomly created from 1246 smokers in a clinical trial. Exploratory and confirmatory factor analyses were conducted to identify and select a model that best represented the data. Measurement invariance was assessed to determine if the factors and their content were consistent prior to and during the quit. Improvement in construct overlap within this model was compared against the implicit measurement model using correlational analyses. RESULTS: A 5-factor measurement model composed of negative affect, somatic symptoms, sleep problems, positive affect, and craving fits the data well prior to and during quitting. All factor content except somatic symptoms was consistent over time. Correlational analyses indicated that the 5-factor model attenuated construct overlap compared to the implicit model. CONCLUSIONS: The models generated from data-driven approaches (eg, the 5-factor model) reduced overlap and better represented the constructs underlying these measures. This approach created distinct, stable constructs that span over measures of side effects and potential treatment mechanisms. IMPLICATIONS: This study demonstrated that measures assessing treatment mechanisms, withdrawal symptoms, and side effects contain problematic overlap that reduces the clarity of these key constructs. The use of data-driven approaches showed that these measures do not map on to their posited latent constructs (eg, the Minnesota Nicotine Withdrawal Scale does not yield a withdrawal factor). Rather, these measures form distinct, basic processes that may represent more meaningful constructs for future research on cessation and treatment. Assessments designed to individually examine these processes may improve the study of treatment mechanisms.