Comparative effectiveness of motivation phase intervention components for use with smokers unwilling to quit: a factorial screening experiment

Abstract

Aims: To screen promising intervention components designed to reduce smoking and promote abstinence in smokers initially unwilling to quit.

Design: A balanced, four-factor, randomized factorial experiment.

Setting: Eleven primary care clinics in southern Wisconsin, USA.

Participants: A total of 517 adult smokers (63.4% women, 91.1% white) recruited during primary care visits who were willing to reduce their smoking but not quit.

Interventions: Four factors contrasted intervention components designed to reduce smoking and promote abstinence: (1) nicotine patch versus none; (2) nicotine gum versus none; (3) motivational interviewing (MI) versus none; and (4) behavioral reduction counseling (BR) versus none. Participants could request cessation treatment at any point during the study.

Measurements: The primary outcome was percentage change in cigarettes smoked per day at 26 weeks post-study enrollment; the secondary outcomes were percentage change at 12 weeks and point-prevalence abstinence at 12 and 26 weeks post-study enrollment.

Findings: There were few main effects, but a significant four-way interaction at 26 weeks post-study enrollment (P = 0.01, β = 0.12) revealed relatively large smoking reductions by two component combinations: nicotine gum combined with BR and BR combined with MI. Further, BR improved 12-week abstinence rates (P = 0.04), and nicotine gum, when used without MI, increased 26-week abstinence after a subsequent aided quit attempt (P = 0.01).

Conclusions: Motivation-phase nicotine gum and behavioral reduction counseling are promising intervention components for smokers who are initially unwilling to quit.

Keywords: Chronic care smoking treatment; Multi-phase Optimization Strategy (MOST); Phase-Based Model; comparative effectiveness; factorial experiment; motivational interviewing; nicotine replacement therapy; primary care; smoking cessation; smoking reduction.

Figure 1

CONSORT diagram

Figure 2

a. Bar graph showing interactions for mean percent reduction in cigarettes per day at 12 weeks post study enrollment. b. Bar graph showing interactions for mean percent reduction in cigarettes per day at 26 weeks post study enrollment.

Figure 2

a. Bar graph showing interactions for mean percent reduction in cigarettes per day at 12 weeks post study enrollment. b. Bar graph showing interactions for mean percent reduction in cigarettes per day at 26 weeks post study enrollment.

Figure 3

Bar graphs for Gum X BR and Gum X MI interactions for the 26-week point-prevalence abstinence model for the full sample (n = 517)

Figure 4

Bar graphs showing Gum X MI and Gum X BR interactions for the 26-week point-prevalence abstinence model among participants who received cessation treatment (n=100)