Systematic review
Cognitive therapies for smoking cessation: a systematic review
Systematic review
|Published
We evaluated the effect of cognitive therapies on smoking cessation. We included 21 randomised controlled trials.
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Key message
Around six million people die every year due to diseases caused by smoking, most commonly cancer, cardiovascular disease and chronic obstructive pulmonary disease. Nicotine replacement therapy, medication and counselling are common methods used to help people quit smoking.
We evaluated the effect of cognitive therapies on smoking cessation. We included 21 randomised controlled trials. The included studies involved adult smokers, different patient groups, and persons at risk of heart disease.
We found that:
- Cognitive therapies combined with medication probably improve smoking abstinence rates somewhat, compared to medication only, moderate-quality evidence
- Cognitive therapies combined with nicotine replacement therapy may improve smoking abstinence rates somewhat, compared to other interventions combined with nicotine replacement therapy, low-quality evidence.
- Cognitive therapies may improve smoking abstinence rates, compared to other interventions, up to 12 months after the end of the intervention, low-quality evidence.
- Cognitive therapies may have little or no effect on smoking abstinence rates, compared to usual care or minimal intervention, low-quality evidence.
We are uncertain whether cognitive therapies combined with medication change smoking abstinence rates compared to supportive therapy combined with medication.
Summary
Background
Around six million people die every year due to diseases caused by smoking. In 2013, smoking accounted for 14.5% of all deaths in Norway, primarily caused by cancer, cardiovascular disease and chronic obstructive pulmonary disease. Both pharmacological and non-pharmacological interventions, and combinations of the two, are used to help people quit smoking. Cognitive therapies are considered effective treatments for a range of disorders such as depression, anxiety, insomnia, and chronic pain. There are also documented effects of cognitive therapies when used to change health behaviours such as physical activity and dietary habits, but we do not know the effects of cognitive therapies on smoking cessation.
Objective
We carried out this systematic review to answer the question “What is the effect of cognitive therapies on smoking cessation in adults ≥ 18 years, compared to no intervention, usual care or another intervention?”
Methods
We searched systematically in five electronic databases for systematic reviews and subsequently for randomised or cluster-randomised controlled trials. We included studies that evaluated effects of cognitive therapies on smoking cessation compared to no intervention, usual care, or other interventions in adults aged 18 years and older. In addition, we searched the reference lists of included studies. Two persons independently screened titles and abstracts, selected studies based on full text publications, and assessed risk of bias in the included studies. One person extracted data from the studies and another person verified the data extraction. We summarized the results by random-effects meta-analyses, presented as relative risk and 95% confidence intervals. We rated our confidence in the effect estimates using GRADE (Grading of Recommendations Assessment, Development and Evaluation) and presented the results in summary of findings tables. In the GRADE system, high quality means that we are very confident that the estimate of the effect is close to the true effect; moderate quality that the estimate of the effect is likely to be close to the true effect, but there is a possibility that it is substantially different; low quality that the estimate of the effect may be substantially different from the true effect; and very low quality that the estimate of the effect is likely to be substantially different from the true effect.
Results
We did not find any systematic reviews that could answer our question. We found 21 randomized controlled trials with a total of 4946 participants that fulfilled our inclusion criteria. Half of the included studies involved adult smokers, six studies involved patient groups, and the remaining studies included people from specific ethnic groups or women only. The control groups received either no intervention, usual care or other interventions, and most studies reported seven-day smoking abstinence rates. Thirteen studies had follow-up times six months or more after the end of the intervention. We judged 18 studies to have an unclear risk of bias, two studies to have a low risk of bias, and one study to have a high risk of bias.
We found small effects of cognitive therapies in combination with medication or nicotine replacement therapy for smoking cessation.
- Cognitive therapies in combination with medication, resulted in a higher smoking abstinence rate compared to medication only. The relative risk based on five studies with 673 participants was 1.39 with a 95% confidence interval of 1.10 to 1.76. According to GRADE, we rated our confidence in the effect estimate as moderate.
- Cognitive therapies combined with nicotine replacement therapy resulted in a higher smoking abstinence rate, compared to other interventions combined with nicotine replacement therapy. The relative risk based on eight studies with 1 309 participants was 1.53 with a 95% confidence interval of 1.06 to 2.19. We rated our confidence in the effect estimate as low.
- Cognitive therapies resulted in a higher abstinence rate, compared to other interventions. The relative risk based on six studies with 850 participants was 2.05 with a confidence interval of 1.09 to 3.86. We rated our confidence in the effect estimate as low.
We found that cognitive therapies may have little or no effect compared to usual care or minimal intervention on smoking abstinence rate. We rated our confidence in the effect estimate as low.
We are uncertain whether cognitive therapies combined with medication compared to supportive therapy combined with medication change smoking abstinence rates. We rated our confidence in the effect estimates as very low.
Discussion
The study participants in this review were diverse and included both adult smokers and patients in hospital- or primary health care settings. The interventions involved basic elements of cognitive therapies, such as relapse prevention, coping skills, self-management, self-efficacy, social support, cognitive restructuring, and problem solving. Several different health professions delivered the interventions, although with a predominance of psychologists. There was great variation in the duration and frequency of the therapy sessions.
Exclusion of persons with co-morbidities, mental health problems, or dependence on other substances (e.g. alcohol, illicit drugs) may limit the applicability of the results. Our results may not capture how effective cognitive therapies for smoking cessation will be under routine clinical practice.
Almost all studies used biochemical validation of self-reported smoking abstinence, and most studies reported abstinence seven days before the follow-up date. This indicates a relatively homogeneous approach to measurement of smoking abstinence. Further improvement of measurement procedures include standardization of the follow-up period (e.g. sustained since quit-date or seven days before follow-up), and standardization of cut-off levels to identify regular smokers by biochemical analyses.
Research gaps include lack of direct comparison with pharmacological treatment or other active interventions such as exercise, and evaluation of sustained abstinence from intervention/quit date to follow up. Uncertainty regarding the documentation as such includes insufficient power in trials and insufficient reporting of research methods, especially procedures for randomization and allocation concealment.
Conclusion
Cognitive therapies added to medication probably improve smoking abstinence rates somewhat compared to medication only. Cognitive therapies combined with nicotine replacement therapy may improve smoking abstinence somewhat compared to other interventions combined with nicotine replacement therapy. Cognitive therapies may improve smoking abstinence rates as compared to other interventions. Cognitive therapies may have a similar effect as usual care or minimal intervention on smoking abstinence rate. We are uncertain whether cognitive therapy combined with medication changes smoking abstinence rate as compared to supportive therapy combined with medication.
