Attrition during a randomized controlled trial of reduced nicotine content cigarettes as a proxy for understanding acceptability of nicotine product standards.

AIMS: To determine (1) if nicotine content affects study attrition-a potential behavioral measure of acceptability-in a trial that required compliance with three levels of reduced nicotine content (RNC) cigarettes, and (2) if attrition is associated with subjective and behavioral responses to RNC cigarettes.

DESIGN: Secondary analysis of a 35-day, parallel-design, open-label, randomized controlled trial. After a 5-day baseline period, participants were randomized to smoke for three 10-day periods: their preferred brand (control group) or RNC cigarettes with three nicotine levels in a within-subject stepdown (one group: high-moderate-low) or non-stepdown (five groups: high-low-moderate, low-moderate-high, low-high-moderate, moderate-low-high, moderate-high-low) fashion.

SETTING: A single site in Philadelphia, PA, USA.

PARTICIPANTS: A total of 246 non-treatment-seeking daily smokers [mean age = 39.52, cigarettes per day (CPD) = 20.95, 68.3% white] were recruited from October 2007 to June 2013.

MEASUREMENTS: The primary outcome was attrition. Key predictors were nicotine content transition and study period. Exploratory predictors were taste and strength subjective ratings, total puff volume and carbon monoxide (CO) boost. Covariates included: age, gender, race, education and nicotine dependence.

FINDINGS: Overall attrition was 31.3% (n = 77): 24.1% of the control and 25.0% of the stepdown RNC cigarette groups dropped out versus 44.6% of non-stepdown groups (P = 0.006). Compared with controls, attrition odds were 4.5 and 4.7 times greater among smokers transitioning from preferred and the highest RNC cigarettes to the lowest RNC cigarettes, respectively (P = 0.001 and 0.003). Providing more favorable initial taste ratings of study cigarettes decreased attrition odds by 2% (P = 0.012).

CONCLUSIONS: The majority of participants completed a 35-day trial of varying levels of reduced nicotine content cigarettes. Participant dropout was greater for cigarettes with lower nicotine content and less in smokers reporting more favorable subjective ratings of the cigarettes.