Hoda Abdellatif BDS, MPH, DrPH
Motivational interviewing (MI) may assist smokers to quit. However, the results should be interpreted with caution due to variations in study quality, treatment fidelity and the possibility of publication or selective reporting bias.
This high quality review, considering only RCTs, finds a definite, but modest, effect of MI on smoking cessation. The implications are somewhat compromised by the evidence which involves MI of varying approaches across studies, is not specific about which MI components are effective, and the review shows some publication bias.
Among people who smoke, does motivational interviewing increase the rate of abstinence at 6 months, decrease the relapse rate, and have no significant harmful effects when compared to usual care or brief advice?
Trials of this systematic review were identified from the Cochrane Collaboration’s Tobacco Addiction Review Group specialized register. The authors followed a defined protocol, with two independent reviewers identifying studies and extracting data. I Inclusion criteria were: 1) a randomized clinical trial (RCT) or cluster RCT, and 2) the intervention was based upon MI principles (e.g. exploring ambivalence, decision balance, assessment of motivation and confidence to quit, eliciting ’change talk’ and supporting self-efficacy). The participants were tobacco users of either gender recruited in any setting excluding pregnant women and adolescent smokers.. The primary outcome measure was abstinence from smoking after at least six months follow up. Meta analysis and subgroup analyses, and tests for publication bias were performed.
This systematic review identified 14 studies published between 1997 and 2008, involving over 10,000 smokers. Trials were conducted in one to four sessions, with the duration of each session ranging from 15 to 45 minutes. All but two of the trials used supportive telephone contacts, and supplemented the counseling with self-help materials. MI was generally compared with brief advice or usual care in the trials. Interventions were delivered by primary care physicians, hospital clinicians, nurses or counselors.
Overall, the meta-analysis demonstrated moderate, statistically significant results favoring the MI over brief advice or usual care in quitting (RR 1.27; 95% CI 1.14 to 1.42). Subgroup analyses suggested that MI was effective when delivered by primary care physicians (RR 3.49; 95% CI 1.53 to 7.94) and by counselors (RR 1.27; 95% CI 1.12 to 1.43), and when it was conducted in longer sessions (more than 20 minutes per session) (RR 1.31; 95% CI 1.16 to 1.49). Multiple session treatments may be slightly more effective than single sessions, but both regimens produced positive outcomes. Publication bias was assessed showing presence of bias toward positive results.
Motivational interviewing may assist smokers to quit. However, the results should be interpreted with caution due to variations in study quality, treatment approaches and the possibility of publication or selective reporting bias.
Source of Funding:
Internal from the Department of Health, Hong Kong. Professional Development and Quality Assurance
Importance and Context:
Cigarette smoking remains one of the leading causes of preventable disease worldwide. Various pharmacological and non-pharmacological methods to assist smoking cessation are available. Recently motivational interviewing(MI) has become an important patient-centered method of counseling that is designed to help treat addictions and to motivate behavioral change. The effectiveness of MI has been shown for alcohol, drugs, weight control, diet and exercise. However, there has been little attempt to systematically review the evidence on MI applied specifically to smoking cessation.
Strengths and Weaknesses of the Systematic Review:
The research question and well-defined eligibility criteria were pre-established. A comprehensive search (limited to English and Chinese language) of quality sources (Tobacco Addiction Group Register and the MINT database) was conducted, screened for relevance, and followed by two independent data extractions. No attempt was made to include unpublished research. Risk of bias for each study was assessed. Appropriately the relative risk served as a summary measure. Pooling was carried out through fixed-effects models by default, but without justification. Mixed-effects models were carried out in the case of significant heterogeneity across studies resulting in better estimates of the intervention effect. Publication bias was assessed. Selected subgroup and sensitivity analyses were carried out to address respectively heterogeneity and the robustness of the results.
Strengths and Weaknesses of the Evidence:
Fourteen RCTs were included in this review, with over 10,000 subjects. All addressed the research question for this systematic review. All used some variant of MI, and the outcome was consistently abstinence from smoking (though the validity with which it was measured (self-report and biochemical analyses) varied. Those studies in which both were employed, showed discrepancy. Findings were homogeneous across studies. A weakness of the evidence is the variation across the trials in treatment fidelity. Critical details in how MI was modified for the particular study population, the training of therapists and the content of the counseling were lacking from some trial reports. The funnel plot of the included studies suggested publication bias and/or selective reporting which may compromise the quality of the evidence in this review.
Implications for Dental Practice:
It is clear from the review that in general MI assists, albeit to a modest degree, smoking cessation, especially when delivered for longer sessions (more than 20 minutes) and by general practitioners or in a general practice setting. Not clear from this review is the identification of which components of MI and counseling techniques have the greatest effect.