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The impact of perceived treatment assignment on smoking cessation outcomes among African-American smokers.

ABSTRACT: The double-blind placebo-controlled design is commonly considered the gold standard in research methodology; however, subject expectation bias could subvert blinding.The primary aim of this study was to examine the impact of expectation bias. Specifically, we examined perceived treatment assignment on smoking cessation outcome rates among participants enrolled in a clinical trial of bupropion (150 mg SR, BID).Analyses were conducted on data collected during "Kick It at Swope," a double-blind, placebo-controlled, randomized trial of 600 African-American smokers. Chi-square and multiple logistic regression analyses were used to examine the impact of perception of assignment on treatment effect and cotinine-verified smoking abstinence rates.Participants were predominantly middle-aged (mean 44.7, SD 11.2), African-American women (68.6%), who smoked 19 CPD (SD = 8.1). Most had completed at least a high school education or GED (51.6%), and 55% had a monthly family income <$1,800.At week 6 (end of treatment) and week 26 (end of study), participants were asked to report their perceived treatment group assignment. Self-reported abstinence (weeks 6 and 26) was confirmed using CO and cotinine biochemical verification.After adjusting for actual treatment assignment, age and baseline cotinine, participants who perceived being assigned to bupropion vs. placebo were more likely to be abstinent at weeks 6 (OR = 2.07, 95% CI: 1.29 to 3.33, p = 0.002) and 26 (OR = 1.85, 95% CI: 1.05 to 3.24, p = 0.032).Results support previous research that expectation bias associated with judgment of treatment assignment is a strong predictor of outcome and confirms this relationship in a smoking cessation trial using bupropion SR among African-American smokers.

SUBMITTER: Thomas JL

PROVIDER: S-EPMC2518039 | biostudies-other | 2008 Sep

REPOSITORIES: biostudies-other

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Project description:Previous research demonstrated the efficacy of sustained release bupropion (bupropion SR) for smoking cessation in whites as well as moderate to heavy (?10 cigarettes per day [CPD]) African American smokers. We evaluated whether bupropion SR was effective for smoking cessation among African American light smokers (?10 CPD).A randomized, double-blind placebo-controlled trial was conducted from December 27, 2007, to May 13, 2010. All participants were African American light smokers (?10 CPD), aged 18 years or older. Participants were randomly assigned to receive 300 mg bupropion SR (150 mg once daily for 3 days and then 150 mg twice daily) (n = 270 participants) or placebo (n = 270 participants) for 7 weeks, and up to six sessions of health education counseling. Serum cotinine was measured at baseline (week 0). The primary outcome was salivary cotinine-verified 7-day point prevalence smoking abstinence at week 26; a cut point of 15 ng/mL differentiated smokers from nonsmokers. Salivary cotinine-verified smoking abstinence at end of medication treatment at week 7 was also examined. Odds ratios (OR) for smoking abstinence and 95% confidence intervals (CIs) were calculated using logistic regression models. All statistical tests were two-sided.Participants at baseline visit (week 0) smoked an average of 8.0 CPD and had a mean serum cotinine level of 275.8 ng/mL (SD = 155.8 ng/mL); most used menthol cigarettes (83.7%) and smoked within 30 minutes of waking (72.2%). After imputing those lost to follow-up as smokers, no statistically significant difference in long-term smoking abstinence rates at week 26 was observed between bupropion SR and placebo groups (13.3% vs 10.0%, OR = 1.39, 95% CI = 0.82 to 2.35, P = .23). Cotinine-verified smoking abstinence rate at end of medication week 7 was higher in the bupropion SR vs placebo group (23.7% vs 9.6%, OR = 2.92, 95% CI = 1.78 to 4.77, P < .001).Bupropion SR was effective in promoting smoking cessation during the medication phase of treatment but showed no effect on long-term smoking cessation among African American light smokers. More research is needed to identify strategies for sustaining abstinence among African American light smokers.

Project description:IntroductionNegative affect has been identified as a factor influencing continued smoking during pregnancy. In this study, a multi-component emotion regulation intervention was developed to address negative emotional smoking triggers and pilot-tested among low-income pregnant smokers. Treatment feasibility and acceptability, cotinine-verified rates of smoking cessation, and self-report of mean cigarettes smoked were assessed.MethodsPregnant smokers who self-reported smoking in response to negative affect (N = 70) were randomly assigned to receive one of two 8-session interventions: (1) emotion regulation treatment combined with standard cognitive-behavioral smoking cessation (ERT + CBT) or (2) a health and lifestyle plus standard smoking cessation active control (HLS + CBT). Outcomes for the 4-month period following the quit date are reported.ResultsTreatment attendance and subjective ratings provide evidence for the feasibility and acceptability of the ERT + CBT intervention. Compared with the HLS + CBT control condition, the ERT + CBT condition demonstrated higher abstinence rates at 2 months (ERT + CBT = 23% vs. HLS + CBT = 0%, OR = 13.51; 95% CI = 0.70-261.59) and 4 months (ERT = 18% vs. HLS = 5%; OR = 2.98; 95% CI = 0.39-22.72) post-quit. Mean number of cigarettes per day was significantly lower in ERT + CBT at 2 months (ERT + CBT = 2.73 (3.35) vs. HLS + CBT = 5.84 (6.24); p = .05) but not at 4 months (ERT + CBT = 2.15 (3.17) vs. HLS + CBT = 5.18 (2.88); p = .06) post-quit.ConclusionsThe development and initial test of the ERT + CBT intervention supports its feasibility and acceptability in this difficult-to-treat population. Further development and testing in a Stage II randomized clinical trial are warranted.ImplicationsNegative affect has been identified as a motivator for continued smoking during pregnancy. To date, smoking cessation interventions for pregnant smokers have not specifically addressed the role of negative affect as a smoking trigger. This treatment development pilot study provides support for the feasibility and acceptability of a multi-component ERT + CBT for low-income pregnant smokers who self-report smoking in response to negative affect. Study findings support further testing in a fully-powered Stage II efficacy trial powered to assess mediators and moderators of treatment effects.

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The impact of perceived treatment assignment on smoking cessation outcomes among African-American smokers.

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