This study examined initial changes in nicotine withdrawal, craving, perceived control over withdrawal symptoms, and self-efficacy to quit smoking as predictors of end-of-treatment and long-term abstinence from smoking following a treatment program that provided behavioral counseling and NRT. The prospective nature of the study design, inclusion of community smokers as participants, and the evaluation of relatively novel predictors of abstinence provided an opportunity to enhance our understanding of predictors of response to treatment for nicotine dependence. Overall, while relatively more traditional predictors of treatment response, including changes in nicotine withdrawal and nicotine craving, did not predict treatment response, two less-studied predictors - perceived control over withdrawal symptoms and self-efficacy to quit smoking - did predict treatment response.
Trial participants who exhibited a greater increase in perceived control over withdrawal symptoms over the course of the first three weeks of treatment were significantly more likely to be abstinent at the end-of-treatment; this change, however, did not predict long-term abstinence assessed six months after the quit date. Nevertheless, to the best of our knowledge, this is the first study to link this variable with response to treatment for nicotine dependence. Further, this result converges with general theories of health behaviors [14
] and an extensive literature that associates increased perceptions of control with more favorable health outcomes [13
]. Moreover, this result suggests that behavioral strategies aimed at helping smokers increase their perceptions of control over abstinence-induced symptoms can help with at least the early phases of smoking cessation.
In addition, participants who exhibited a greater increase in self-efficacy to quit smoking over the course of the first two weeks of treatment were significantly more likely to be abstinent at the end-of-treatment, and this relationship persisted for the assessment of abstinence conducted six months following the target quit date. This result extends previous descriptive studies that have associated higher levels of self-efficacy to quit smoking with smoking cessation [15
] and converges with recent studies that have associated higher self-efficacy to quit smoking with cessation [16
]. The present study is unique in showing that it is not only higher levels of self-efficacy that predicts cessation but initial increases in this variable following cessation that predicts successful quitting; further, the present results are relatively unique in demonstrating the link between greater self-efficacy to quit smoking and long-term cessation outcomes. Thus, promoting a smoker's early sense of confidence in their ability to quit smoking seems important for enhancing the smoker's likelihood that they will successfully quit smoking following and long after treatment.
These results should be conceptualized in the context of study limitations. First, despite the prospective nature of the study, the analyses are correlational and, thus, no causal interpretations may be discerned from the results. Second, we examined a relatively small number of potential predictors of cessation outcomes in this sample. Given the complexities involved in conducting an effectiveness trial in a cooperative group, we were restricted in terms of the length of study surveys and frequency of measurement time-points. Third, since this was an effectiveness clinical trial, we emphasized external validity vs. internal validity, which is a greater concern in efficacy trials. This decision was based on the objective of examining the impact of these NRTs in a “real-world” setting and with smokers who otherwise would have limited access to such clinical trials. As such, the eligibility criteria were minimized, the behavioral counseling was limited, and the treatments were unblinded. These factors may certainly have influenced the study results. Fourth, the change scores used to predict cessation may have been influenced by the participant's experience with the interventions and the participant's success or failure with cessation. Lastly, there was missing survey and outcome data from this trial. However, the amount of missing data in this trial is typical of community-based smoking cessation effectiveness trials [23
Nevertheless, the present study findings augment our current understanding of factors that predict response to treatment for nicotine dependence. In particular, while controlling for demographic and smoking-related variables that predict treatment response, smokers who experience a greater increase in perceived control over withdrawal symptoms and quitting self-efficacy during the initial few weeks following a designated quit attempt are more likely to be successful with quitting smoking following treatment with behavioral counseling and NRT. Interventions for smokers that specifically target these two processes may show higher rates of treatment success, thereby contributing to further reductions in the overall prevalence rate of smoking.